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Sample records for antiferromagnetic vortex states

  1. Ferromagnetic and antiferromagnetic order in bacterial vortex lattices

    E-Print Network [OSTI]

    Hugo Wioland; Francis G. Woodhouse; Jörn Dunkel; Raymond E. Goldstein

    2015-11-16

    Despite their inherent non-equilibrium nature, living systems can self-organize in highly ordered collective states that share striking similarities with the thermodynamic equilibrium phases of conventional condensed matter and fluid systems. Examples range from the liquid-crystal-like arrangements of bacterial colonies, microbial suspensions and tissues to the coherent macro-scale dynamics in schools of fish and flocks of birds. Yet, the generic mathematical principles that govern the emergence of structure in such artificial and biological systems are elusive. It is not clear when, or even whether, well-established theoretical concepts describing universal thermostatistics of equilibrium systems can capture and classify ordered states of living matter. Here, we connect these two previously disparate regimes: Through microfluidic experiments and mathematical modelling, we demonstrate that lattices of hydrodynamically coupled bacterial vortices can spontaneously organize into distinct phases of ferro- and antiferromagnetic order. The preferred phase can be controlled by tuning the vortex coupling through changes of the inter-cavity gap widths. The emergence of opposing order regimes is tightly linked to the existence of geometry-induced edge currents, reminiscent of those in quantum systems. Our experimental observations can be rationalized in terms of a generic lattice field theory, suggesting that bacterial spin networks belong to the same universality class as a wide range of equilibrium systems.

  2. A new reversal mode in exchange coupled antiferromagnetic/ferromagnetic disks: distorted viscous vortex

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Gilbert, Dustin A.; Ye, Li; Varea, Aïda; Agramunt-Puig, Sebastià; del Valle, Nuria; Navau, Carles; López-Barbera, José Francisco; Buchanan, Kristen S.; Hoffmann, Axel; Sánchez, Alvar; et al

    2015-04-28

    Magnetic vortices have generated intense interest in recent years due to their unique reversal mechanisms, fascinating topological properties, and exciting potential applications. In addition, the exchange coupling of magnetic vortices to antiferromagnets has also been shown to lead to a range of novel phenomena and functionalities. Here we report a new magnetization reversal mode of magnetic vortices in exchange coupled Ir20Mn80/Fe20Ni80 microdots: distorted viscous vortex reversal. In contrast to the previously known or proposed reversal modes, the vortex is distorted close to the interface and viscously dragged due to the uncompensated spins of a thin antiferromagnet, which leads to unexpectedmore »asymmetries in the annihilation and nucleation fields. These results provide a deeper understanding of the physics of exchange coupled vortices and may also have important implications for applications involving exchange coupled nanostructures.« less

  3. Direct Imaging of Antiferromagnetic Vortex States

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  4. Direct Imaging of Antiferromagnetic Vortex States

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  5. Direct Imaging of Antiferromagnetic Vortex States

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  6. Direct Imaging of Antiferromagnetic Vortex States

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  7. Direct Imaging of Antiferromagnetic Vortex States

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  8. Direct Imaging of Antiferromagnetic Vortex States

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  9. Direct Imaging of Antiferromagnetic Vortex States

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  10. Direct Imaging of Antiferromagnetic Vortex States

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  11. Theory of the algebraic vortex liquid in an anisotropic spin-2 triangular antiferromagnet

    E-Print Network [OSTI]

    "roton" minima in the excitation spectrum recently reported in series expansions can be accounted antiferromagnet Cs2CuCl4 stimulated renewed interest in possible spin-liquid phases proximate to the nearest laws at intermediate energies, both in the ordered phase and in a range of temperatures above TN

  12. Large vortex state in ferromagnetic disks

    E-Print Network [OSTI]

    Metlov, Konstantin L

    2013-01-01

    Magnetic vortices in soft ferromagnetic nano-disks have been extensively studied for at least several decades both for their fundamental (as a "live" macroscopic realization of a field theory model of an elementary particle) as well as applied value for high-speed high-density power-independent information storage. Here it is shown that there is another vortex state in nano-scale ferromagnetic disks of several exchange lengths in size. The energy of this large vortex state is computed numerically (within the framework of Magnetism@home distributed computing project) and its stability is studied analytically, which allows to plot it on magnetic phase diagram. It is the ground state of cylinders of certain sizes and is metastable in a wider set of geometries. Large vortices exist on par with classical ones, while being separated by an energy barrier, controllable by tuning the geometry and material of ferromagnetic disk. This state can be an excellent candidate for magnetic information storage not only because ...

  13. Ferroelectric nanostructure having switchable multi-stable vortex states

    DOE Patents [OSTI]

    Naumov, Ivan I. (Fayetteville, AR); Bellaiche, Laurent M. (Fayetteville, AR); Prosandeev, Sergey A. (Fayetteville, AR); Ponomareva, Inna V. (Fayetteville, AR); Kornev, Igor A. (Fayetteville, AR)

    2009-09-22

    A ferroelectric nanostructure formed as a low dimensional nano-scale ferroelectric material having at least one vortex ring of polarization generating an ordered toroid moment switchable between multi-stable states. A stress-free ferroelectric nanodot under open-circuit-like electrical boundary conditions maintains such a vortex structure for their local dipoles when subject to a transverse inhomogeneous static electric field controlling the direction of the macroscopic toroidal moment. Stress is also capable of controlling the vortex's chirality, because of the electromechanical coupling that exists in ferroelectric nanodots.

  14. Vortex Molecular Crystal and Vortex Plastic Crystal States in Honeycomb and Kagome Pinning Arrays

    E-Print Network [OSTI]

    C. Reichhardt; C. J. Olson Reichhardt

    2007-07-26

    Using numerical simulations, we investigate vortex configurations and pinning in superconductors with honeycomb and kagome pinning arrays. We find that a variety of novel vortex crystal states can be stabilized at integer and fractional matching field densities. The honeycomb and kagome pinning arrays produce considerably more pronounced commensuration peaks in the critical depinning force than triangular pinning arrays, and also cause additional peaks at noninteger matching fields where a portion of the vortices are located in the large interstitial regions of the pinning lattices. For the honeycomb pinning array, we find matching effects of equal strength at most fillings B/B_\\phi=n/2 for n>2, where n is an integer, in agreement with recent experiments. For kagome pinning arrays, pronounced matching effects generally occur at B/B_\\phi=n/3 for n>3, while for triangular pinning arrays pronounced matching effects are observed only at integer fillings B/B_\\phi=n. At the noninteger matching field peaks in the honeycomb and kagome pinning arrays, the interstitial vortices are arranged in dimer, trimer, and higher order n-mer states that have an overall orientational order. We call these n-mer states "vortex molecular crystals" and "vortex plastic crystals" since they are similar to the states recently observed in colloidal molecular crystal systems. We argue that the vortex molecular crystals have properties in common with certain spin systems such as Ising and n-state Potts models. We show that kagome and honeycomb pinning arrays can be useful for increasing the critical current above that of purely triangular pinning arrays.

  15. Theory of static and dynamic antiferromagnetic vortices in LSCO superconductors

    E-Print Network [OSTI]

    Hu, Jiangping

    Theory of static and dynamic antiferromagnetic vortices in LSCO superconductors Jiang-Ping Hu, Shou. Here we review theoretical progress since the original proposal and present a theory of static experimental definition of the AFVS, where static AF order coexists with the vortex state of the superconductor

  16. Electronic states near a quantum fluctuating point vortex in a d-wave superconductor: Dirac fermion theory

    E-Print Network [OSTI]

    -point motion in a d-wave superconductor. The vortex is treated as a point flux tube, carrying fluxElectronic states near a quantum fluctuating point vortex in a d-wave superconductor: Dirac fermion model of the low-energy electronic states in the vicinity of a vortex undergoing quantum zero

  17. Spin waves in circular soft magnetic dots at the crossover between vortex and single domain state

    E-Print Network [OSTI]

    Metlushko, Vitali

    Facility, Cornell University, Ithaca, New York, 14853 USA 6Departamento de Fisica de Materiales We report on linear spin dynamics in the vortex state of Permalloy cylindrical dots subjected In many physical systems such as liquids, plasma, super- conductors, ferromagnets, etc., the topological

  18. arXiv:cond-mat/0606001v222Jul2006 Electronic states near a quantum fluctuating point vortex in a d-wave superconductor

    E-Print Network [OSTI]

    -wave superconductor. The vortex is treated as a point flux tube, carrying flux of an auxiliary U(1) gauge fieldarXiv:cond-mat/0606001v222Jul2006 Electronic states near a quantum fluctuating point vortex in a d energy electronic states in the vicinity of a vortex under- going quantum zero-point motion in a d

  19. A finite element method with mesh adaptivity for computing vortex states in fastrotating BoseEinstein condensates

    E-Print Network [OSTI]

    Recanati, Catherine

    A finite element method with mesh adaptivity for computing vortex states in fast­rotating Bose­Einstein Abstract Numerical computations of stationary states of fast­rotating Bose­Einstein condensates require rotation rates). Key words: Gross--Pitaevskii equation, finite element method, mesh adaptivity, Bose­Einstein

  20. Analytic treatment of vortex states in cylindrical superconductors in applied axial magnetic field

    SciTech Connect (OSTI)

    Ludu, A.; Van Deun, J.; Cuyt, A.; Milosevic, M. V.; Peeters, F. M.

    2010-08-15

    We solve the linear Ginzburg-Landau (GL) equation in the presence of a uniform magnetic field with cylindrical symmetry and we find analytic expressions for the eigenfunctions in terms of the confluent hypergeometric functions. The discrete spectrum results from an implicit equation associated to the boundary conditions and it is resolved in analytic form using the continued fractions formalism. We study the dependence of the spectrum and the eigenfunctions on the sample size and the surface conditions for solid and hollow cylindrical superconductors. Finally, the solutions of the nonlinear GL formalism are constructed as expansions in the linear GL eigenfunction basis and selected by minimization of the free energy. We present examples of vortex states and their energies for different samples in enhancing/suppressing superconductivity surroundings.

  1. A numerical study of steady-state vortex configurations and vortex pinning in type-II superconductors 

    E-Print Network [OSTI]

    Kim, Sangbum

    2006-04-12

    In part I, a numerical study of the mixed states in a mesoscopic type-II superconducting cylinder is described. Steady-state configurations and transient behavior of the magnetic vortices for various values of the applied ...

  2. Two-hole bound states from a systematic low-energy effective field theory for magnons and holes in an antiferromagnet

    SciTech Connect (OSTI)

    Bruegger, C.; Kaempfer, F.; Moser, M.; Wiese, U.-J.; Pepe, M.

    2006-12-01

    Identifying the correct low-energy effective theory for magnons and holes in an antiferromagnet has remained an open problem for a long time. In analogy to the effective theory for pions and nucleons in QCD, based on a symmetry analysis of Hubbard and t-J-type models, we construct a systematic low-energy effective field theory for magnons and holes located inside pockets centered at lattice momenta ({+-}({pi}/2a),{+-}({pi}/2a)). The effective theory is based on a nonlinear realization of the spontaneously broken spin symmetry and makes model-independent universal predictions for the entire class of lightly doped antiferromagnetic precursors of high-temperature superconductors. The predictions of the effective theory are exact, order by order in a systematic low-energy expansion. We derive the one-magnon exchange potentials between two holes in an otherwise undoped system. Remarkably, in some cases the corresponding two-hole Schroedinger equations can even be solved analytically. The resulting bound states have d-wave characteristics. The ground state wave function of two holes residing in different hole pockets has a d{sub x{sup 2}-y{sup 2}}-like symmetry, while for two holes in the same pocket the symmetry resembles d{sub xy}.

  3. Crystalline Electric Field as a Probe for Long-Range Antiferromagnetic Order and Superconducting State of CeFeAsO1-xFx

    SciTech Connect (OSTI)

    Chi, Songxue; Adroja, D. T.; GUIDI, T.; Bewley, Robert I.; Li, Shiliang; Zhao, Jun; Lynn, J. W.; Brown, C. M.; Qiu, Y.; Chen, G. F,; Luo, J. L.; Wang, N. L.; Dai, Pengcheng

    2008-01-01

    We use inelastic neutron scattering to study the crystalline electric field (CEF) excitations of Ce{sup 3+} in CeFeAsO{sub 1-x}F{sub x} (x=0, 0.16). For nonsuperconducting CeFeAsO, the Ce CEF levels have three magnetic doublets in the paramagnetic state, but these doublets split into six singlets when the Fe ions order antiferromagnetically. For superconducting CeFeAsO{sub 0.84}F{sub 0.16} (T{sub c} = 41 K), where the static antiferromagnetic order is suppressed, the Ce CEF levels have three magnetic doublets at {h_bar}{sub {omega}} = 0, 18.7, 58.4 meV at all temperatures. Careful measurements of the intrinsic linewidth {Lambda} and the peak position of the 18.7 meV mode reveal a clear anomaly at T{sub c}, consistent with a strong enhancement of local magnetic susceptibility {chi}{double_prime}({h_bar}{sub {omega}}) below T{sub c}. These results suggest that CEF excitations in the rare-earth oxypnictides can be used as a probe of spin dynamics in the nearby FeAs planes.

  4. Spintronics in antiferromagnets

    SciTech Connect (OSTI)

    Soh, Yeong-Ah; Kummamuru, Ravi K.

    2012-05-10

    Magnetic domains and the walls between are the subject of great interest because of the role they play in determining the electrical properties of ferromagnetic materials and as a means of manipulating electron spin in spintronic devices. However, much less attention has been paid to these effects in antiferromagnets, primarily because there is less awareness of their existence in antiferromagnets, and in addition they are hard to probe since they exhibit no net magnetic moment. In this paper, we discuss the electrical properties of chromium, which is the only elemental antiferromagnet and how they depend on the subtle arrangement of the antiferromagnetically ordered spins. X-ray measurement of the modulation wavevector Q of the incommensurate antiferromagnetic spin-density wave shows thermal hysteresis, with the corresponding wavelength being larger during cooling than during warming. The thermal hysteresis in the Q vector is accompanied with a thermal hysteresis in both the longitudinal and Hall resistivity. During cooling, we measure a larger longitudinal and Hall resistivity compared with when warming, which indicates that a larger wavelength at a given temperature corresponds to a smaller carrier density or equivalently a larger antiferromagnetic ordering parameter compared to a smaller wavelength. This shows that the arrangement of the antiferromagnetic spins directly influences the transport properties. In thin films, the sign of the thermal hysteresis for Q is the same as in thick films, but a distinct aspect is that Q is quantized.

  5. Model of Antiferromagnetic Superconductivity

    E-Print Network [OSTI]

    Geoffrey L. Sewell

    2015-09-28

    We present a simple model that supports superconductive and antiferromagnetic ordering. The model consists of a system of electrons on a simple cubic lattice that move by tunnel effect and interact via antiferromagnetic Ising spin couplings and short range repulsions: these include infinitely strong Hubbard forces that prevent double occupancy of any lattice site. Hence, under the filling condition of one electron per site and at sufficiently low temperature, the system is an antiferromagnetic Mott insulator. However, when holes are created by suitable doping, they are mobile charge carriers. We show that, at low concentration, their interactions induced by the above interelectronic ones lead to Schafroth pairing. Hence, under certain plausible but unproved assumptions, the model exhibits the off-diagonal long range order that characterises superconductivity, while retaining the antiferromagnetic ordering.

  6. A tensor product state approach to spin-1/2 square J1-J2 antiferromagnetic Heisenberg model: evidence for deconfined quantum criticality

    E-Print Network [OSTI]

    Ling Wang; Zheng-Cheng Gu; Frank Verstraete; Xiao-Gang Wen

    2015-07-14

    The ground state phase diagram of spin-1/2 J1-J2 antiferromagnetic Heisenberg model on square lattice around the maximally frustrated regime (J2~0.5J1) has been debated for decades. Here we study this model using a recently proposed novel numerical method - the cluster update algorithm for tensor product states (TPSs). The ground state energies at finite sizes and in the thermodynamic limit (with finite size scaling) are in good agreement with exact diagonalization study. At the largest bond dimension available D = 9 and through finite size scaling of the magnetization order near the transition point, we accurately determine the critical point Jc=0.5321(2)J1 and the critical exponent beta = 0.499(3). In the range of 0.5321power law decaying dimer-dimer correlation, which suggests a potential gapless U(1) spin liquid phase. However, since the U(1) spin liquid is unstable due to the instanton effect, a VBS order with very small amplitude might develop at long wave length. Remarkably, by fitting a universal scaling function for the spin-spin correlation with fixed Jc find the critical exponents nu=0.68(3) and eta=0.34(3), which is in very good agreement to the observed critical exponents for deconfined quantum critical point (DQCP) in other systems. Thus, our numerical results strongly suggest a Landau forbidden phase transition from Neel order to VBS order at Jc=0.5321(2)J1.

  7. Piezo-antiferromagnetic effect of sawtooth-like graphene nanoribbons

    SciTech Connect (OSTI)

    Zhao, Shangqian; Lu, Yan; Zhang, Yuchun; Lu, Wengang Liang, Wenjie

    2014-05-19

    A type of sawtooth-like graphene nanoribbon (SGNR) with piezo-antiferromagnetic effect is studied numerically. The ground state of the studied SGNR changes from nonmagnetic state to antiferromagnetic state with uniaxial strain. The changes of the spin-charge distributions during the stretching are investigated. The Hubbard model reveals that the hopping integrals between the ?-orbitals of the carbon atoms are responsible to the piezo-antiferromagnetic effect. The study sheds light on the application of graphene-based structures to nanosensors and spintronic devices.

  8. MICROMAGNETIC STUDIES OF THE TRANSITION BETWEEN VORTEX AND SINGLE-DOMAIN STATES IN SUB-100 NM NANODOTS 

    E-Print Network [OSTI]

    King, Andrew

    2012-04-26

    20 40 60 80 100 120 140 To ta l E ne rg y (e V ) Vortex-­?Core Posi2on (nm) Total Energy vs. Vortex-­?Core Posi2on 65 nm Diameter Iron Dot 0 kOe 0.5 kOe 17... B ar ri er (e V ) Applied Field (kOe) Energy Barriers vs. Applied Field 40 nm Diameter Iron Dot Vortex Annihila:on Vortex Nuclea:on 21 FIG. 8. Energy barriers plotted versus applied...

  9. Kapitza problem for the magnetic moments of synthetic antiferromagnetic systems

    SciTech Connect (OSTI)

    Dzhezherya, Yu. I.; Demishev, K. O.; Korenivskii, V. N.

    2012-08-15

    The dynamics of magnetization in synthetic antiferromagnetic systems with the magnetic dipole coupling in a rapidly oscillating field has been examined. It has been revealed that the system can behave similar to the Kapitza pendulum. It has been shown that an alternating magnetic field can be efficiently used to control the magnetic state of a cell of a synthetic antiferromagnet. Analytical relations have been obtained between the parameters of such an antiferromagnet and an external magnetic field at which certain quasistationary states are implemented.

  10. Antiferromagnetic domain size and exchange bias 

    E-Print Network [OSTI]

    Fitzsimmons, M. R.; Lederman, D.; Cheon, M.; Shi, H.; Olamit, J.; Roshchin, Igor V.; Schuller, Ivan K.

    2008-01-01

    Using neutron diffraction, we measured the sizes of antiferromagnetic domains in three ferromagnet/antiferromagnet bilayer samples as a function of the magnitude and sign of exchange bias, temperature, and antiferromagnet composition. Neutron...

  11. Steady-state and equilibrium vortex configurations, transitions, and evolution in a mesoscopic superconducting cylinder 

    E-Print Network [OSTI]

    Kim, S.; Hu, Chia-Ren; Andrews, MJ.

    2004-01-01

    A numerical scheme to study the mixed states in a mesoscopic type-II superconducting cylinder is described. Steady-state configurations and transient behavior of the magnetic vortices for various values of the applied magnetic field H are presented...

  12. Antiferromagnetic Spins Do The Twist

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

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  13. NUMERICAL SIMULATION OF VORTEX BREAKDOWN

    E-Print Network [OSTI]

    Prete, Vincenza Del

    2011-01-01

    irrotational vortex. NRC Con. Aero Rep. LR-378. Hald, O. &vortex breakdown" phenomenon. Aero Dept. , Imperial ColI.

  14. Doped antiferromagnets in high dimension E. W. Carlson, S. A. Kivelson, and Z. Nussinov

    E-Print Network [OSTI]

    Carlson, Erica

    of a doped antiferromagnet on a d-dimensional hyper- cubic lattice are evaluated using a systematic expansion received 18 November 1997 The ground-state properties of the t-J model on a d-dimensional hypercubic

  15. Spatially resolved penetration depth measurements and vortex manipulation in the ferromagnetic superconductor ErNi2B2C

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wulferding, Dirk; Yang, Ilkyu; Yang, Jinho; Lee, Minkyung; Choi, Hee Cheul; Bud'ko, Sergey L.; Canfield, Paul C.; Yeom, Han Woong; Kim, Jeehoon

    2015-07-31

    We present a local probe study of the magnetic superconductor ErNi2B2C, using magnetic force microscopy at sub-Kelvin temperatures. ErNi2B2C is an ideal system to explore the effects of concomitant superconductivity and ferromagnetism. At 500 mK, far below the transition to a weakly ferromagnetic state, we directly observe a structured magnetic background on the micrometer scale. We determine spatially resolved absolute values of the magnetic penetration depth ? and study its temperature dependence as the system undergoes magnetic phase transitions from paramagnetic to antiferromagnetic, and to weak ferromagnetic, all within the superconducting regime. We estimate the absolute pinning force of Abrikosovmore »vortices, which shows a position dependence and temperature dependence as well, and discuss the possibility of the purported spontaneous vortex formation.« less

  16. Entanglement of strongly interacting low-dimensional fermions in metallic, superfluid, and antiferromagnetic insulating systems

    SciTech Connect (OSTI)

    Franca, V. V.; Capelle, K.

    2006-10-15

    We calculate the entanglement entropy of strongly correlated low-dimensional fermions in metallic, superfluid, and antiferromagnetic insulating phases. The entanglement entropy reflects the degrees of freedom available in each phase for storing and processing information, but is found not to be a state function in the thermodynamic sense. The role of critical points, smooth crossovers, and Hilbert space restrictions in shaping the dependence of the entanglement entropy on the system parameters is illustrated for metallic, insulating, and superfluid systems. The dependence of the spin susceptibility on entanglement in antiferromagnetic insulators is obtained quantitatively. The opening of spin gaps in antiferromagnetic insulators is associated with enhanced entanglement near quantum critical points.

  17. NUMERICAL SIMULATION OF VORTEX BREAKDOWN

    E-Print Network [OSTI]

    Prete, Vincenza Del

    2011-01-01

    axis of the tube and is called the vortex core. The basicthe tube plus a perturbation caused by the vortex breakdown.of the tube. Thus the occurrence of the vortex breakdown

  18. Improved vortex reactor system

    DOE Patents [OSTI]

    Diebold, James P. (Lakewood, CO); Scahill, John W. (Evergreen, CO)

    1995-01-01

    An improved vortex reactor system for affecting fast pyrolysis of biomass and Refuse Derived Fuel (RDF) feed materials comprising: a vortex reactor having its axis vertically disposed in relation to a jet of a horizontally disposed steam ejector that impels feed materials from a feeder and solids from a recycle loop along with a motive gas into a top part of said reactor.

  19. Vortex diode jet

    DOE Patents [OSTI]

    Houck, Edward D. (Idaho Falls, ID)

    1994-01-01

    A fluid transfer system that combines a vortex diode with a jet ejector to transfer liquid from one tank to a second tank by a gas pressurization method having no moving mechanical parts in the fluid system. The vortex diode is a device that has a high resistance to flow in one direction and a low resistance to flow in the other.

  20. Distinct magnetic signatures of fractional vortex configurations in multiband superconductors

    SciTech Connect (OSTI)

    Silva, R. M. da; Domínguez, D.; Aguiar, J. Albino

    2014-12-08

    Vortices carrying fractions of a flux quantum are predicted to exist in multiband superconductors, where vortex core can split between multiple band-specific components of the superconducting condensate. Using the two-component Ginzburg-Landau model, we examine such vortex configurations in a two-band superconducting slab in parallel magnetic field. The fractional vortices appear due to the band-selective vortex penetration caused by different thresholds for vortex entry within each band-condensate, and stabilize near the edges of the sample. We show that the resulting fractional vortex configurations leave distinct fingerprints in the static measurements of the magnetization, as well as in ac dynamic measurements of the magnetic susceptibility, both of which can be readily used for the detection of these fascinating vortex states in several existing multiband superconductors.

  1. PHYSICAL REVIEW E 78, 036304 2008 Variational principle in dynamics of a vortex ...lament

    E-Print Network [OSTI]

    Berdichevsky, Victor

    A vortex ...lament is a thin tube such that vorticity is negligible in a vicinity of this tube while insidePHYSICAL REVIEW E 78, 036304 2008 Variational principle in dynamics of a vortex ...lament Victor L in dynamics of vortex ...lament Victor L. Berdichevsky Mechanical Engineering, Wayne State University, Detroit

  2. Antiferromagnetic Exchange Interaction between Electrons on Degenerate LUMOs in Benzene Dianion

    E-Print Network [OSTI]

    Matsuura, Hiroyasu; Fukuyama, Hidetoshi

    2012-01-01

    We discuss the ground state of Benzene dianion (Bz$^{2-}$) on the basis of the numerical diagonalization method of an effective model of $\\pi$ orbitals. It is found that the ground state can be the spin singlet state, and the exchange coupling between LUMOs can be antiferromagnetic.

  3. Erratum: Evolution of antiferromagnetic susceptibility under...

    Office of Scientific and Technical Information (OSTI)

    susceptibility under uniaxial pressure inBa(Fe1-xCox)2As2Phys. Rev. B89, 214404 (2014) Citation Details In-Document Search Title: Erratum: Evolution of antiferromagnetic...

  4. Electron vortex beams in a magnetic field and spin filter

    E-Print Network [OSTI]

    Debashree Chowdhury; Banasri Basu; Pratul Bandyopadhyay

    2015-02-25

    We investigate the propagation of electron vortex beams in a magnetic field. It is pointed out that when electron vortex beams carrying orbital angular momentum propagate in a magnetic field, the Berry curvature associated with the scalar electron moving in a cyclic path around the vortex line is modified from that in free space. This alters the spin-orbit interaction, which affects the propagation of nonparaxial beams. The electron vortex beams with tilted vortex lead to spin Hall effect in free space. In presence of a magnetic field in time space we have spin filtering such that either positive or negative spin states emerge in spin Hall currents with clustering of spin $\\frac{1}{2}$ states.

  5. The Holographic Superconductor Vortex

    E-Print Network [OSTI]

    Marc Montull; Alex Pomarol; Pedro J. Silva

    2009-09-02

    A gravity dual of a superconductor at finite temperature has been recently proposed. We present the vortex configuration of this model and study its properties. In particular, we calculate the free energy as a function of an external magnetic field, the magnetization and the superconducting density. We also find the two critical magnetic fields that define the region in which the vortex configurations are energetically favorable.

  6. Improved vortex reactor system

    DOE Patents [OSTI]

    Diebold, J.P.; Scahill, J.W.

    1995-05-09

    An improved vortex reactor system is described for affecting fast pyrolysis of biomass and Refuse Derived Fuel (RDF) feed materials comprising: a vortex reactor having its axis vertically disposed in relation to a jet of a horizontally disposed steam ejector that impels feed materials from a feeder and solids from a recycle loop along with a motive gas into a top part of said reactor. 12 figs.

  7. Vortex-Based Aero- and Hydrodynamic Estimation

    E-Print Network [OSTI]

    Hemati, Maziar Sam

    2013-01-01

    Vortex-Based Aero- and Hydrodynamic Estimation . . . . . .2 Aero- andbenefit from vortex-based aero- and hydrodynamic estimation.

  8. Chiral specific electron vortex beam spectroscopy

    E-Print Network [OSTI]

    J. Yuan; S. M. Lloyd; M. Babiker

    2013-07-29

    Electron vortex beams carry well-defined orbital angular momentum (OAM) about the propagation axis. Such beams are thus characterised by chirality features which make them potentially useful as probes of magnetic and other chiral materials. An analysis of the inelastic processes in which electron vortex beams interact with atoms and which involve OAM exchange is outlined, leading to the multipolar selection rules governing this chiral specific electron vortex beam spectroscopy. Our results show clearly that the selection rules are dependent on the dynamical state and location of the atoms involved. In the most favorable scenario, this form of electron spectroscopy can induce magnetic sublevel transitions which are commonly probed using circularly polarized photon beams.

  9. Temperature-dependent terahertz magnetic dipole radiation from antiferromagnetic GdFeO{sub 3} ceramics

    SciTech Connect (OSTI)

    Fu, Xiaojian; Xi, Xiaoqing; Bi, Ke; Zhou, Ji

    2013-11-18

    Temperature-dependent terahertz magnetic dipole radiation in antiferromagnetic GdFeO{sub 3} ceramic is investigated both theoretically and experimentally in this work. A two-level quantum transition mechanism is introduced to describe the excitation-radiation process, and radiative lifetime is derived analytically from the change of spin state density during this process. Terahertz spectral measurements demonstrate that the radiative frequency exhibits a red-shift and lifetime shortens as temperature increases, which is in good agreement with theoretical predictions. The temperature-sensitive radiative frequency and excellent terahertz emission mean that the antiferromagnetic ceramics show potential for application in terahertz sensors and frequency-tunable terahertz lasers.

  10. Vortex-Based Aero- and Hydrodynamic Estimation

    E-Print Network [OSTI]

    Hemati, Maziar Sam

    2013-01-01

    1. The strength of a vortex tube is uniform along the tube.3. The strength of a vortex tube is invariant in time. Theof Vortex Ring Formation at the Edge of a Circular Tube. ”

  11. GREEN'S FUNCTIONS OF VORTEX OPERATORS

    E-Print Network [OSTI]

    Polchinski, Joseph

    2013-01-01

    8 g Olesen vortex • , somewhere in space. The tube between cvortex operators have surface clustering, as this implies that magnetic flux is forming into tubes.

  12. Motion of a helical vortex

    E-Print Network [OSTI]

    Fuentes, Oscar Velasco

    2015-01-01

    We study the motion of a single helical vortex in an unbounded, inviscid, incompressible fluid. The vortex is an infinite tube whose centerline is a helix and whose cross section is a circle of small radius (compared to the radius of curvature) where the vorticity is uniform and parallel to the centerline. Ever since Joukowsky (1912) deduced that this vortex translates and rotates steadily without change of form, numerous attempts have been made to compute these self-induced velocities. Here we use Hardin's (1982) solution for the velocity field to find new expressions for the vortex's linear and angular velocities. Our results, verified by numerically computing the Helmholtz integral and the Rosenhead-Moore approximation to the Biot-Savart law, are more accurate than previous results over the whole range of values of the vortex pitch and cross-section. We then use the new formulas to study the advection of passive particles near the vortex; we find that the vortex's motion and capacity to transport fluid dep...

  13. Elementary Vortex Processes in Thermal Superfluid Turbulence

    E-Print Network [OSTI]

    Kivotides, Demosthenes; Wilkin, S. Louise

    2009-01-01

    a complex system of vortex tubes has only (a vigorouslyIn this context, the vortex tube model (VTM) of Kivotidesstraight normal ?uid vortex tube, suggested an explicit

  14. Emergent Power-Law Phase in the 2D Heisenberg Windmill Antiferromagnet: A Computational Experiment

    E-Print Network [OSTI]

    Chandra, Premi

    Emergent Power-Law Phase in the 2D Heisenberg Windmill Antiferromagnet: A Computational Experiment online). Finite temperature phase diagram of classical windmill Heisenberg antiferromagnet as a function

  15. Electronic structure reconstruction across the antiferromagnetic transition in TaFe????Te? spin ladder

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Xu, Min; Wang, Li -Min; Peng, Rui; Ge, Qing -Qin; Chen, Fei; Ye, Zi -Rong; Zhang, Yan; Chen, Su -Di; Xia, Miao; Liu, Rong -Hua; et al

    2015-02-01

    With angle-resolved photoemission spectroscopy, we studied the electronic structure of TaFe????Te?, a two-leg spin ladder compound with a novel antiferromagnetic ground state. Quasi-two-dimensional Fermi surface is observed, with sizable inter-ladder hopping. Moreover, instead of observing an energy gap at the Fermi surface in the antiferromagnetic state, we observed the shifts of various bands. Combining these observations with density-functional-theory calculations, we propose that the large scale reconstruction of the electronic structure, caused by the interactions between coexisting itinerant electrons and local moments, is most likely the driving force of the magnetic transition. Thus TaFe????Te? serves as a simpler platform that containsmore »similar ingredients as the parent compounds of iron-based superconductors.« less

  16. Vortex lattice for a holographic superconductor

    E-Print Network [OSTI]

    Kengo Maeda; Makoto Natsuume; Takashi Okamura

    2009-12-17

    We investigate the vortex lattice solution in a (2+1)-dimensional holographic model of superconductors constructed from a charged scalar condensate. The solution is obtained perturbatively near the second-order phase transition and is a holographic realization of the Abrikosov lattice. Below a critical value of magnetic field, the solution has a lower free energy than the normal state. Both the free energy density and the superconducting current are expressed by nonlocal functions, but they reduce to the expressions in the Ginzburg-Landau (GL) theory at long wavelength. As a result, a triangular lattice becomes the most favorable solution thermodynamically as in the GL theory of type II superconductors.

  17. PUBLISHED ONLINE: 23 AUGUST 2009 | DOI: 10.1038/NPHYS1369 Inertia-driven spin switching in antiferromagnets

    E-Print Network [OSTI]

    Loss, Daniel

    LETTERS PUBLISHED ONLINE: 23 AUGUST 2009 | DOI: 10.1038/NPHYS1369 Inertia-driven spin switching to the spin system to overcome the potential barrier and reorient into a new metastable state, long after terms such as acceleration. In contrast, the dynamics of an antiferromagnet with two sublattices M1

  18. Exploiting lens aberrations to create electron vortex beams

    E-Print Network [OSTI]

    L. Clark; A. Béché; G. Guzzinati; A. Lubk; M. Mazilu; R. Van Boxem; J. Verbeeck

    2013-07-18

    A model for a new electron vortex beam production method is proposed and experimentally demonstrated. The technique calls on the controlled manipulation of the degrees of freedom of the lens aberrations to achieve a helical phase front. These degrees of freedom are accessible by using the corrector lenses of a transmission electron microscope. The vortex beam is produced through a particular alignment of these lenses into a specifically designed astigmatic state and applying an annular aperture in the condensor plane. Experimental results are found to be in good agreement with simulations.

  19. Fragile antiferromagnetism in the heavy-fermion compound YbBiPt

    SciTech Connect (OSTI)

    Ueland, Benjamin G. [Ames Laboratory; Kreyssig, Andreas [Ames Laboratory; Prokes, K. [Helmholtz-Zentrum Berlin fur Materialien und Energie; Lynn, J. W. [NIST Center for Neutron Research; Harriger, L. W. [NIST Center for Neutron Research; Pratt, D. K. [NIST Center for Neutron Research; Singh, D. K. [NIST Center for Neutron Research; Heitmann, T. W. [University of Missouri; Sauerbrei, Samantha [Ames Laboratory; Saunders, Scott M. [Ames Laboratory; Mun, E. D. [Ames Laboratory; Budko, Serguei L. [Ames Laboratory; McQueeney, Robert J. [Ames Laboratory; Canfield, Paul C. [Ames Laboratory; Goldman, Alan I. [Ames Laboratory

    2014-05-08

    We report results from neutron scattering experiments on single crystals of YbBiPt that demonstrate antiferromagnetic order characterized by a propagation vector, ?AFM = (121212), and ordered moments that align along the [1 1 1] direction of the cubic unit cell. We describe the scattering in terms of a two-Gaussian peak fit, which consists of a narrower component that appears below TN?0.4 K and corresponds to a magnetic correlation length of ?n? 80 Å, and a broad component that persists up to T?? 0.7 K and corresponds to antiferromagnetic correlations extending over ?b? 20 Å. Our results illustrate the fragile magnetic order present in YbBiPt and provide a path forward for microscopic investigations of the ground states and fluctuations associated with the purported quantum critical point in this heavy-fermion compound.

  20. Excitation spectrum of a model antiferromagnetic spin-trimer.

    SciTech Connect (OSTI)

    Stone, Matthew B; Fernandez-Alonso, F.; Adroja, D. T.; Dalal, N. S.; Villagran, D.; Cotton, F. A.; Nagler, Stephen E

    2007-01-01

    We present an inelastic neutron scattering (INS) study of the excitation spectrum of a quantum S=1/2 equilateral Heisenberg trimer, Cu{sub 3}(O{sub 2}C{sub 16}H{sub 23}){sub 61.2}C{sub 6}H{sub 12}. The magnetic properties of the system can be described by an ensemble of independent equilateral triangles of S=1/2 Cu{sup 2+} ions. With antiferromagnetic Heisenberg coupling, the ground state of each trimer is a degenerate pair of S=1/2 doublets, with a quartet S=3/2 excited state. Previous bulk measurements led to an estimate for the excitation energy of 28 meV. Here, we report INS measurements that can provide a direct measurement of magnetic excitation energies. These measurements are challenging since inter- and intramolecular vibrational modes associated with the organic ligands are at frequencies similar to the magnetic excitations. Measurements on a nonmagnetic compound with the same ligands as well as the temperature dependence of the neutron scattering cross section are used to identify the vibrational modes. This leads to an identification of the magnetic excitation energy as being approximately 37 meV at T=10 K, with a gradual softening with increasing temperature.

  1. Gravity waves from vortex dipoles and jets 

    E-Print Network [OSTI]

    Wang, Shuguang

    2009-05-15

    The dissertation first investigates gravity wave generation and propagation from jets within idealized vortex dipoles using a nonhydrostatic mesoscale model. Several initially balanced and localized jets induced by vortex dipoles are examined here...

  2. Competing interactions in ferromagnetic/antiferromagnetic perovskite superlattices

    E-Print Network [OSTI]

    Takamura, Y.

    2010-01-01

    antiferromagnetic perovskite superlattices  Y.  TakamuraSr 0.3 MnO 3   (LSMO) perovskite oxide superlattices leads Specifically, the class of perovskite oxides  (ABO 3 ) has 

  3. Unified molecular field theory for collinear and noncollinear Heisenberg antiferromagnets

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Johnston, David C.

    2015-02-27

    In this study, a unified molecular field theory (MFT) is presented that applies to both collinear and planar noncollinear Heisenberg antiferromagnets (AFs) on the same footing. The spins in the system are assumed to be identical and crystallographically equivalent. This formulation allows calculations of the anisotropic magnetic susceptibility ? versus temperature T below the AF ordering temperature TN to be carried out for arbitrary Heisenberg exchange interactions Jij between arbitrary neighbors j of a given spin i without recourse to magnetic sublattices. The Weiss temperature ?p in the Curie-Weiss law is written in terms of the Jij values and TNmore »in terms of the Jij values and an assumed AF structure. Other magnetic and thermal properties are then expressed in terms of quantities easily accessible from experiment as laws of corresponding states for a given spin S. For collinear ordering these properties are the reduced temperature t=T/TN, the ratio f = ?p/TN, and S. For planar noncollinear helical or cycloidal ordering, an additional parameter is the wave vector of the helix or cycloid. The MFT is also applicable to AFs with other AF structures. The MFT predicts that ?(T ? TN) of noncollinear 120° spin structures on triangular lattices is isotropic and independent of S and T and thus clarifies the origin of this universally observed behavior. The high-field magnetization and heat capacity for fields applied perpendicular to the ordering axis (collinear AFs) and ordering plane (planar noncollinear AFs) are also calculated and expressed for both types of AF structures as laws of corresponding states for a given S, and the reduced perpendicular field versus reduced temperature phase diagram is constructed.« less

  4. Magnetoelastic Coupling and Symmetry Breaking in the Frustrated Antiferromagnet {alpha}-NaMnO{sub 2}

    SciTech Connect (OSTI)

    Giot, Maud; Chapon, Laurent C.; Radaelli, Paolo G.; Androulakis, John; Lappas, Alexandros; Green, Mark A.

    2007-12-14

    The magnetic and crystal structures of the {alpha}-NaMnO{sub 2} have been determined by high-resolution neutron powder diffraction. The system maps out a frustrated triangular spin lattice with anisotropic interactions that displays two-dimensional spin correlations below 200 K. Magnetic frustration is lifted through magneto-elastic coupling, evidenced by strong anisotropic broadening of the diffraction profiles at high temperature and ultimately by a structural phase transition at 45 K. In this low-temperature regime a three-dimensional antiferromagnetic state is observed with a propagation vector k=((1/2),(1/2),0)

  5. Magnitude of the magnetic exchange interaction in the heavy-fermion antiferromagnet CeRhIn?

    SciTech Connect (OSTI)

    Das, Pinaki [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Lin, S. -Z. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Ghimire, N.? J. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Huang, K. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Univ. of California, San Diego, La Jolla, CA (United States); Ronning, F. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Bauer, E.? D. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Thompson, J.? D. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Batista, C.? D. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Ehlers, G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Janoschek, M. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)

    2014-12-01

    We have used high-resolution neutron spectroscopy experiments to determine the complete spin wave spectrum of the heavy-fermion antiferromagnet CeRhIn?. The spin wave dispersion can be quantitatively reproduced with a simple frustrated J??J? model that also naturally explains the magnetic spin-spiral ground state of CeRhIn? and yields a dominant in-plane nearest-neighbor magnetic exchange constant J?=0.74(3)??meV. Our results pave the way to a quantitative understanding of the rich low-temperature phase diagram of the prominent CeTIn? (T = Co, Rh, Ir) class of heavy-fermion materials.

  6. Localized Induction Equation for Stretched Vortex Filament

    E-Print Network [OSTI]

    Kimiaki Konno; Hiroshi Kakuhata

    2006-03-02

    We study numerically the motion of the stretched vortex filaments by using the localized induction equation with the stretch and that without the stretch.

  7. Light propagation around a relativistic vortex flow of dielectric medium

    E-Print Network [OSTI]

    B. Linet

    2000-11-06

    We determine the path of the light around a dielectric vortex described by the relativistic vortex flow of a perfect fluid.

  8. Vortex Hydro Energy Develops Transformational Technology to Harness...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Vortex Hydro Energy Develops Transformational Technology to Harness Energy from Water Currents Vortex Hydro Energy Develops Transformational Technology to Harness Energy from Water...

  9. arXiv:1206.2498v2[cond-mat.other]19Nov2012 Quantum vortex reconnections

    E-Print Network [OSTI]

    Caliari, Marco

    (Dated: 21 November 2012) We study reconnections of quantum vortices by numerically solving the governing . They are the key to understanding quantum turbulence8 , a disordered state of vortex lines which is easily created

  10. The idea of vortex energy

    E-Print Network [OSTI]

    V. E. Shapiro

    2011-09-22

    This work formulates and gives grounds for general principles and theorems that question the energy function doctrine and its quantum version as a genuine law of nature without borders of adequacy. The emphasis is on the domain where the energy of systems is conserved -- I argue that only in its tiny part the energy is in the kinetic, potential and thermal forms describable by a generalized thermodynamic potential, whereas otherwise the conserved energy constitutes a whole linked to vortex forces, and can be a factor of things like persistent currents and dark matter.

  11. Vortex Tubes of Turbulent Solar Convection

    E-Print Network [OSTI]

    Kitiashvili, I N; Mansour, N N; Lele, S K; Wray, A A

    2011-01-01

    Investigation of turbulent properties of solar convection is extremely important for understanding of the multi-scale dynamics observed on the solar surface. In particular, recent high-resolution observations revealed ubiquitous vortical structures, and numerical simulations demonstrated links between the vortex tube dynamics and magnetic field organization, and also importance of vortex tube interactions in the mechanism of acoustic wave excitation on the Sun. In this paper we investigate mechanisms of formation of vortex tubes in highly-turbulent convective flows near the solar surface by using realistic radiative hydrodynamic LES simulations. Analysis of data, obtained by the simulations, indicates two basic processes of the vortex tube formation: 1) development of small-scale convective instability inside convective granules, and 2) a Kelvin-Helmholtz type instability of shearing flows in intergranular lanes. Our analysis shows that vortex stretching during these processes is a primary source of generatio...

  12. EXISTENCE OF KNOTTED VORTEX TUBES IN STEADY EULER FLOWS

    E-Print Network [OSTI]

    Enciso, Alberto

    EXISTENCE OF KNOTTED VORTEX TUBES IN STEADY EULER FLOWS ALBERTO ENCISO AND DANIEL PERALTA-SALAS Abstract. We prove the existence of knotted and linked thin vortex tubes for steady solutions of vortex tubes of a Beltrami field that tends to zero at infinity. The structure of the vortex lines

  13. Vortex pinning by inhomogeneities in type-II superconductors

    E-Print Network [OSTI]

    Chapman, Jon

    Vortex pinning by inhomogeneities in type-II superconductors S.J. Chapman #3;y G. Richardson zx of a curvilinear vortex in an inhomogeneous type-II superconducting material in the limit as the vortex core radius of the superconducting electrons acts as a pinning potential for the vortex, so that vortices will be attracted

  14. Under consideration for publication in J. Fluid Mech. 1 Some steady axisymmetric vortex ows past

    E-Print Network [OSTI]

    Fornberg, Bengt

    include vortex rings, bounded vortices attached to the sphere and in nite vortex tubes. Four families to be considered: vortex rings, bounded vortices attached to the sphere, and vortex tubes" extending to in nity. Fornberg and K. Miller = 0: attached vortex vortex ring > 0: vortex tube Figure 1. Examples

  15. Two-step liquid-solid vortex transition with the field along the ab planes in YBa2Cu3O7 crystals

    E-Print Network [OSTI]

    Grigera, Santiago

    , in the mixed state of clean and twinned YBa2Cu3O7 single crystals, support the existence of a vortex and Instituto Balseiro, Comisio´n Nacional de Energi´a Ato´mica, 8400 San Carlos de Bariloche, Argentina-smectic phase when the vortices interact with an attractive periodic potential. The transition from the vortex

  16. Vortex Lattices and Crystalline Geometries

    E-Print Network [OSTI]

    Ning Bao; Sarah Harrison; Shamit Kachru; Subir Sachdev

    2013-04-16

    We consider $AdS_2 \\times R^2$ solutions supported by a magnetic field, such as those which arise in the near-horizon limit of magnetically charged $AdS_4$ Reissner-Nordstrom black branes. In the presence of an electrically charged scalar field, such magnetic solutions can be unstable to spontaneous formation of a vortex lattice. We solve the coupled partial differential equations which govern the charged scalar, gauge field, and metric degrees of freedom to lowest non-trivial order in an expansion around the critical point, and discuss the corrections to the free energy and thermodynamic functions arising from the formation of the lattice. We describe how such solutions can also be interpreted, via S-duality, as characterizing infrared crystalline phases of conformal field theories doped by a chemical potential, but in zero magnetic field; the doped conformal field theories are dual to geometries that exhibit dynamical scaling and hyperscaling violation.

  17. Airfoil Vortex Induced Vibration suppression devices

    E-Print Network [OSTI]

    Lee, Evan J. (Evan Joseph)

    2007-01-01

    Vortex Induced Vibrations (VIV) is a major concern of the offshore oil industry. This problem leads to fatigue failure in the marine risers and causes costly replacement of the risers. Appendages such as helical strakes ...

  18. Field induced spin density wave and spiral phases in a layered antiferromagnet

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Stone, Matthew B.; Lumsden, Mark D.; Garlea, Vasile O.; Grenier, B.; Ressouche, E.; Samulon, Eric C.; Fisher, Ian R.

    2015-07-28

    We determine the low-field ordered magnetic phases of the S=1 dimerized antiferromagnet Ba3Mn2O8 using single crystal neutron diffraction. We find that for magnetic fields between ?0H=8.80 T and 10.56 T applied along the [1\\bar{1}0] direction the system exhibits spin density wave order with incommensurate wave vectors of type (?,?,?). For ?0H > 10.56 T, the magnetic order changes to a spiral phase with incommensurate wave vectors only along the [hh0] direction. For both field induced ordered phases, the magnetic moments are lying in the plane perpendicular to the field direction. The nature of these two transitions is fundamentally different: themore »low-field transition is a second order transition to a spin-density wave ground state, while the one at higher field, toward the spiral phase, is of first order.« less

  19. Homometallic and Heterometallic Antiferromagnetic Rings: Magnetic Properties Studied by Nuclear Magnetic Resonance

    SciTech Connect (OSTI)

    Casadei, Cecilia

    2012-05-09

    The aim of the present thesis is to investigate the local magnetic properties of homometallic Cr{sub 8} antiferromagnetic (AFM) ring and the changes occurring by replacing one Cr{sup 3+} ion with diamagnetic Cd{sup 2+} (Cr{sub 7}Cd) and with Ni{sup 2+} (Cr{sub 7}Ni). In the heterometallic ring a redistribution of the local magnetic moment is expected in the low temperature ground state. We have investigated those changes by both {sup 53}Cr-NMR and {sup 19}F-NMR. We have determined the order of magnitude of the transferred hyperfine coupling constant {sup 19}F - M{sup +} where M{sup +} = Cr{sup 3+}, Ni{sup 2+} in the different rings. This latter result gives useful information about the overlapping of the electronic wavefunctions involved in the coordinative bond.

  20. Topological analysis of paraxially scattered electron vortex beams

    E-Print Network [OSTI]

    Axel Lubk; Laura Clark; Giulio Guzzinati; Jo Verbeeck

    2014-10-10

    We investigate topological aspects of sub-nm electron vortex beams upon elastic propagation through atomic scattering potentials. Two main aspects can be distinguished: (i) Significantly reduced delocalization compared to a similar non-vortex beam if the beam centers on an atomic column and (ii) site symmetry dependent splitting of higher-order vortex beams. Furthermore, the results provide insight into the complex vortex line fabric within the elastically scattered wave containing characteristic vortex loops predominantly attached to atomic columns and characteristic twists of vortex lines around atomic columns.

  1. VORTEX CREEP AGAINST TOROIDAL FLUX LINES, CRUSTAL ENTRAINMENT, AND PULSAR GLITCHES

    SciTech Connect (OSTI)

    Gügercino?lu, Erbil; Alpar, M. Ali E-mail: alpar@sabanciuniv.edu

    2014-06-10

    A region of toroidally oriented quantized flux lines must exist in the proton superconductor in the core of the neutron star. This region will be a site of vortex pinning and creep. Entrainment of the neutron superfluid with the crustal lattice leads to a requirement of superfluid moment of inertia associated with vortex creep in excess of the available crustal moment of inertia. This will bring about constraints on the equation of state. The toroidal flux region provides the moment of inertia necessary to complement the crust superfluid with postglitch relaxation behavior fitting the observations.

  2. Vortex dynamics in three-dimensional continuous myocardium with fiber rotation: Filament instability and fibrillationa...

    E-Print Network [OSTI]

    Mascia, Corrado

    Vortex dynamics in three-dimensional continuous myocardium with fiber rotation: Filament, or filament. This twist can then significantly alter the dynamics of the filament. This paper explores transmural filament and cause a transition to a wave turbulent state characterized by a high density

  3. Low NOx Advanced Vortex Combustor

    SciTech Connect (OSTI)

    Edmonds, R.G. (Ramgen Power Systems, Inc., Bellevue, WA); Williams, J.T. (Ramgen Power Systems, Inc., Bellevue, WA); Steele, R.C. (EPRI); Straub, D.L.; Casleton, K.H.; Bining, Avtar (California Energy Commission, Sacramento, CA)

    2008-05-01

    A lean-premixed advanced vortex combustor (AVC) has been developed and tested. The natural gas fueled AVC was tested at the U.S. Department of Energy’s National Energy Technology Laboratory in Morgantown, WV. All testing was performed at elevated pressures and inlet temperatures and at lean fuel-air ratios representative of industrial gas turbines. The improved AVC design exhibited simultaneous NOx /CO/unburned hydrocarbon (UHC) emissions of 4/4/0 ppmv (all emissions corrected to 15% O2 dry). The design also achieved less than 3 ppmv NOx with combustion efficiencies in excess of 99.5%. The design demonstrated marked acoustic dynamic stability over a wide range of operating conditions, which potentially makes this approach significantly more attractive than other lean-premixed combustion approaches. In addition, the measured 1.75% pressure drop is significantly lower than conventional gas turbine combustors, which could translate into an overall gas turbine cycle efficiency improvement. The relatively high velocities and low pressure drop achievable with this technology make the AVC approach an attractive alternative for syngas fuel applications.

  4. Magnitude of the magnetic exchange interaction in the heavy-fermion antiferromagnet CeRhIn5

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Das, Pinaki; Lin, S. -Z.; Ghimire, N. J.; Huang, K.; Ronning, F.; Bauer, E. D.; Thompson, J. D.; Batista, C. D.; Ehlers, G.; Janoschek, M.

    2014-12-08

    We have used high-resolution neutron spectroscopy experiments to determine the complete spin wave spectrum of the heavy-fermion antiferromagnet CeRhIn?. The spin wave dispersion can be quantitatively reproduced with a simple frustrated J?-J? model that also naturally explains the magnetic spin-spiral ground state of CeRhIn? and yields a dominant in-plane nearest-neighbor magnetic exchange constant J?=0.74(3) meV. Our results lead the way to a quantitative understanding of the rich low-temperature phase diagram of the prominent CeTIn? (T = Co, Rh, Ir) class of heavy-fermion materials.

  5. Magnetic Vortex Core Reversal by Low-Field Excitations

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Magnetic Vortex Core Reversal by Low-Field Excitations Magnetic Vortex Core Reversal by Low-Field Excitations Print Wednesday, 28 March 2007 00:00 In micrometer-sized magnetic thin...

  6. Geometric phases for corotating elliptical vortex patches B. N. Shashikantha)

    E-Print Network [OSTI]

    Shashikanth, Banavara N.

    of an infinitely long rectilinear vortex tube of area A whose vorticity distribution is invariant along the lengthGeometric phases for corotating elliptical vortex patches B. N. Shashikantha) Control and Dynamical September 2000 We describe a geometric phase that arises when two elliptical vortex patches co- rotate

  7. Quasi-two Dimensional Hydrodynamics and Interaction of Vortex Tubes

    E-Print Network [OSTI]

    Zakharov, Vladimir

    Quasi-two Dimensional Hydrodynamics and Interaction of Vortex Tubes Vladimir Zakharov 1 but a careful study of the dynamics of the vortex tubes or their systems in a real 3-dimentional nonstationary for description of this type of flow looks very timely. Another motivation is the vortex dynamics

  8. Rogue Waves on a Vortex Filament St Anne's College

    E-Print Network [OSTI]

    Tarrès, Pierre

    Rogue Waves on a Vortex Filament Rehan Shah St Anne's College University of Oxford A dissertation;Abstract The presence of a standing soliton on a vortex filament has been demonstrated theoretically of the local induction approximation (LIA) governing the motion of a thin vortex filament to those of nonlinear

  9. Inelastic electron-vortex-beam scattering

    E-Print Network [OSTI]

    Ruben Van Boxem; Bart Partoens; Jo Verbeeck

    2015-03-16

    Recent theoretical and experimental developments in the field of electron vortex beam physics have raised questions on what exactly this novelty in the field of electron microscopy (and other fields, such as particle physics) really provides. An important part in the answer to those questions lies in scattering theory. The present investigation explores various aspects of inelastic quantum scattering theory for cylindrically symmetric beams with orbital angular momentum. The model system of Coulomb scattering on a hydrogen atom provides the setting to address various open questions: How is momentum transferred? Do vortex beams selectively excite atoms, and how can one employ vortex beams to detect magnetic transitions? The analytical approach presented here provides answers to these questions. OAM transfer is possible, but not through selective excitation; rather, by pre- and post-selection one can filter out the relevant contributions to a specific signal.

  10. Optical vortex array in spatially varying lattice

    E-Print Network [OSTI]

    Kapoor, Amit; Senthilkumaran, P; Joseph, Joby

    2015-01-01

    We present an experimental method based on a modified multiple beam interference approach to generate an optical vortex array arranged in a spatially varying lattice. This method involves two steps which are: numerical synthesis of a consistent phase mask by using two-dimensional integrated phase gradient calculations and experimental implementation of produced phase mask by utilizing a phase only spatial light modulator in an optical 4f Fourier filtering setup. This method enables an independent variation of the orientation and period of the vortex lattice. As working examples, we provide the experimental demonstration of various spatially variant optical vortex lattices. We further confirm the existence of optical vortices by formation of fork fringes. Such lattices may find applications in size dependent trapping, sorting, manipulation and photonic crystals.

  11. Convectively driven vortex flows in the Sun

    E-Print Network [OSTI]

    J. A. Bonet; I. Marquez; J. Sanchez Almeida; I. Cabello; V. Domingo

    2008-09-23

    We have discovered small whirlpools in the Sun, with a size similar to the terrestrial hurricanes (<~0.5 Mm). The theory of solar convection predicts them, but they had remained elusive so far. The vortex flows are created at the downdrafts where the plasma returns to the solar interior after cooling down, and we detect them because some magnetic bright points (BPs) follow a logarithmic spiral in their way to be engulfed by a downdraft. Our disk center observations show 0.009 vortexes per Mm^2, with a lifetime of the order of 5 min, and with no preferred sense of rotation. They are not evenly spread out over the surface, but they seem to trace the supergranulation and the mesogranulation. These observed properties are strongly biased by our type of measurement, unable to detect vortexes except when they are engulfing magnetic BPs.

  12. Bluff Body Flow Simulation Using a Vortex Element Method

    SciTech Connect (OSTI)

    Anthony Leonard; Phillippe Chatelain; Michael Rebel

    2004-09-30

    Heavy ground vehicles, especially those involved in long-haul freight transportation, consume a significant part of our nation's energy supply. it is therefore of utmost importance to improve their efficiency, both to reduce emissions and to decrease reliance on imported oil. At highway speeds, more than half of the power consumed by a typical semi truck goes into overcoming aerodynamic drag, a fraction which increases with speed and crosswind. Thanks to better tools and increased awareness, recent years have seen substantial aerodynamic improvements by the truck industry, such as tractor/trailer height matching, radiator area reduction, and swept fairings. However, there remains substantial room for improvement as understanding of turbulent fluid dynamics grows. The group's research effort focused on vortex particle methods, a novel approach for computational fluid dynamics (CFD). Where common CFD methods solve or model the Navier-Stokes equations on a grid which stretches from the truck surface outward, vortex particle methods solve the vorticity equation on a Lagrangian basis of smooth particles and do not require a grid. They worked to advance the state of the art in vortex particle methods, improving their ability to handle the complicated, high Reynolds number flow around heavy vehicles. Specific challenges that they have addressed include finding strategies to accurate capture vorticity generation and resultant forces at the truck wall, handling the aerodynamics of spinning bodies such as tires, application of the method to the GTS model, computation time reduction through improved integration methods, a closest point transform for particle method in complex geometrics, and work on large eddy simulation (LES) turbulence modeling.

  13. Crystalline Geometries from Fermionic Vortex Lattice

    E-Print Network [OSTI]

    M. Reza Mohammadi Mozaffar; Ali Mollabashi

    2013-08-08

    We study charged Dirac fermions on an AdS$_2\\times R^2$ background with a non-zero magnetic field. Under certain boundary conditions, we show that the charged fermion can make the background unstable, resulting in spontaneously formation of a vortex lattice. We observe that an electric field emerges in the back-reacted solution due to the vortex lattice constructed from spin polarized fermions. This electric field may be extended to the UV boundary which leads to a finite charge density. We also discuss corrections to the thermodynamic functions due to the lattice formation.

  14. Existence of knotted vortex tubes in steady Euler flows

    E-Print Network [OSTI]

    Alberto Enciso; Daniel Peralta-Salas

    2014-10-23

    We prove the existence of knotted and linked thin vortex tubes for steady solutions to the incompressible Euler equation in R^3. More precisely, given a finite collection of (possibly linked and knotted) disjoint thin tubes in R^3, we show that they can be transformed with a C^m-small diffeomorphism into a set of vortex tubes of a Beltrami field that tends to zero at infinity. The structure of the vortex lines in the tubes is extremely rich, presenting a positive-measure set of invariant tori and infinitely many periodic vortex lines. The problem of the existence of steady knotted vortex tubes can be traced back to Lord Kelvin.

  15. On the evolution of vortex rings with swirl

    SciTech Connect (OSTI)

    Naitoh, Takashi, E-mail: naitoh.takashi@nitech.ac.jp [Department of Engineering Physics, Electronics and Mechanics, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan); Okura, Nobuyuki, E-mail: ohkura@meijo-u.ac.jp [Department of Vehicle and Mechanical Engineering, Meijo University, 1-501 Shiogamaguchi Tempaku-ku, Nagoya 468-8502 (Japan); Gotoh, Toshiyuki, E-mail: gotoh.toshiyuki@nitech.ac.jp [Department of Scientific and Engineering Simulation, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan); Kato, Yusuke [Controller Business Unit Engineering Division 1, Engineering Department 3, Denso Wave Incorporated, 1 Yoshiike Kusagi Agui-cho, Chita-gun Aichi 470-2297 (Japan)

    2014-06-15

    A laminar vortex ring with swirl, which has the meridional velocity component inside the vortex core, was experimentally generated by the brief fluid ejection from a rotating outlet. The evolution of the vortex ring was investigated with flow visualizations and particle image velocimetry measurements in order to find the influence of swirling flow in particular upon the transition to turbulence. Immediately after the formation of a vortex ring with swirl, a columnar strong vortex along the symmetric axis is observed in all cases of the present experiment. Then the characteristic fluid discharging from a vortex ring with swirl referred to as “peeling off” appears. The amount of discharging fluid due to the “peeling off” increases with the angular velocity of the rotating outlet. We conjectured that the mechanism generating the “peeling off” is related to the columnar strong vortex by close observations of the spatio-temporal development of the vorticity distribution and the cutting 3D images constructed from the successive cross sections of a vortex ring. While a laminar vortex ring without swirl may develop azimuthal waves around its circumference at some later time and the ring structure subsequently breaks, the swirling flow in a vortex ring core reduces the amplification rate of the azimuthal wavy deformation and preserved its ring structure. Then the traveling distance of a vortex ring can be extended using the swirl flow under certain conditions.

  16. Fast chirality reversal of the magnetic vortex by electric current

    SciTech Connect (OSTI)

    Lim, W. L. Liu, R. H.; Urazhdin, S.; Tyliszczak, T.; Erokhin, S. G.; Berkov, D.

    2014-12-01

    The possibility of high-density information encoding in magnetic materials by topologically stable inhomogeneous magnetization configurations such as domain walls, skyrmions, and vortices has motivated intense research into mechanisms enabling their control and detection. While the uniform magnetization states can be efficiently controlled by electric current using magnetic multilayer structures, this approach has proven much more difficult to implement for inhomogeneous states. Here, we report direct observation of fast reversal of magnetic vortex by electric current in a simple planar structure based on a bilayer of spin Hall material Pt with a single microscopic ferromagnetic disk contacted by asymmetric electrodes. The reversal is enabled by a combination of the chiral Oersted field and spin current generated by the nonuniform current distribution in Pt. Our results provide a route for the efficient control of inhomogeneous magnetization configurations by electric current.

  17. Vortex dynamics in 4 Banavara N. Shashikanth

    E-Print Network [OSTI]

    Shashikanth, Banavara N.

    of oblique vortex shedding behind a heated circular cylinder in laminar wake regime Phys. Fluids 24, 011701 dynamics of Euler's equations for a constant density fluid flow in R4 is studied. Most of the paper focuses of such work are in Refs. 31, 24, 12, 14, and 11. It is fair to say that, in general, classical fluid flows

  18. Quenching Processes in Flame-Vortex Interactions

    E-Print Network [OSTI]

    Zingale, Michael

    for Astrophysical Thermonuclear Flashes 1 , Chicago, IL 60637 y Department of Astronomy and Astrophysics, University-vortex interactions in order to understand quenching of thermonuclear ames. The key question is|can a ther- monuclear. If a ame encounters a 1) The Center for Astrophysical Thermonuclear Flashes is supported by the Department

  19. Antiferromagnetism and domain effects in UPdSn

    SciTech Connect (OSTI)

    Nakotte, H. [Manual Lujan Jr. Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Manual Lujan Jr. Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); [Department of Physics, New Mexico State University, Las Cruces, New Mexico 88003 (United States); Robinson, R.A.; Purwanto, A. [Manuel Lujan Jr. Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Manuel Lujan Jr. Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Tun, Z. [Chalk River Laboratories, Atomic Energy of Canada Limited, Chalk River, Ontario, K0J 1J0 (CANADA)] [Chalk River Laboratories, Atomic Energy of Canada Limited, Chalk River, Ontario, K0J 1J0 (CANADA); Prokes, K.; Brueck, E.; de Boer, F.R. [Van der Waals-Zeeman Institute, University of Amsterdam, 1018 XE Amsterdam (The Netherlands)] [Van der Waals-Zeeman Institute, University of Amsterdam, 1018 XE Amsterdam (The Netherlands)

    1998-10-01

    Neutron-diffraction experiments have been performed on a single crystal of the hexagonal noncollinear antiferromagnetic compound UPdSn as a function of temperature and magnetic field. The use of a special horizontal-field magnet (with very wide horizontal access to the neutron beams) has allowed the study of the principal magnetic Bragg reflections in all three antiferromagnetic domain pairs throughout the magnetic phase diagram for B{lt}3thinspT and T{gt}6thinspK. The data confirm a picture in which one domain pair (1) grows at the expense of the other two domain pairs (2 and 3), for fields along the [100] axis for domain 1. On the other hand, if the field is applied along the perpendicular axis, [010] for domain 1, the other two domains are preferred. These results are consistent with the picture given in a previous vertical-field study of only one magnetic reflection from one domain, in which the 3-T field-induced transition is viewed as a spin-flop transition. There is, however, a small amount of irreversible moment rotation (from {theta}=43{degree} to 48{degree}, where {theta} is the moment canting angle within the hexagonal basal plane), on passing through the spin-flop transition. This seems to be connected with whether the sample is single or multidomain. In addition, the field independence of the N{acute e}el temperature (T{sub N}=37thinspK) has been measured up to 3 T, and data on the domain kinetics are presented. {copyright} {ital 1998} {ital The American Physical Society}

  20. Venturi/vortex technology for controlling chromium electroplating emissions

    SciTech Connect (OSTI)

    Hay, K.J.; Northrup, J. [Army Construction Engineering Research Labs., Champaign, IL (United States); Heck, S.R. [MSE-HKM, Inc., Butte, MT (United States)

    1997-12-31

    A new technology has been developed to control air emissions from hexavalent chromium electroplating tanks. The venturi/vortex scrubber uses a patented drain assembly to pull plating solution, air with toxic particulates above the solution, and unpopped bubbles of generated gases down with a gravity generated vortex effect. The recirculated plating solution acts as the scrubbing liquid and air agitation is eliminated. Separated gases are passed through a condenser/filter to remove any remaining fumes. The device is almost entirely constructed of CPVC. This device offers several advantages over conventional end-of-pipe systems including significantly lower cost, no wastewater, no extensive ventilation system, and emissions are recycled. The system can be is easily retrofitted to existing tanks, however, a loose fitting tank lid is recommended. A pilot demonstration has been performed at Benet Laboratory, Watervliet, NY (US Army) with a 1,500 gallon chromic acid electroplating tank and 1,500 Amps of applied current. Overall chromium emissions results were 0.00002 mg/Amp-hr, surpassing the stringent California State requirement of 0.006 mg/Amp-hr. Emission prevention by capturing unpopped bubbles is the method in which this system reduces the most emissions. The system met current ambient worker safety standards. Two major improvements are recommended: an increase in gas flow rate through the system and a solution to the system`s sensitivity to the plating solution level.

  1. Neutron Scattering Studies of Vortex Matter in Type-II Superconductors

    SciTech Connect (OSTI)

    Xinsheng Ling

    2012-02-02

    The proposed program is an experimental study of the fundamental properties of Abrikosov vortex matter in type-II superconductors. Most superconducting materials used in applications such as MRI are type II and their transport properties are determined by the interplay between random pinning, interaction and thermal fluctuation effects in the vortex state. Given the technological importance of these materials, a fundamental understanding of the vortex matter is necessary. The vortex lines in type-II superconductors also form a useful model system for fundamental studies of a number of important issues in condensed matter physics, such as the presence of a symmetry-breaking phase transition in the presence of random pinning. Recent advances in neutron scattering facilities such as the major upgrade of the NIST cold source and the Spallation Neutron Source are providing unprecedented opportunities in addressing some of the longstanding issues in vortex physics. The core component of the proposed program is to use small angle neutron scattering and Bitter decoration experiments to provide the most stringent test of the Bragg glass theory by measuring the structure factor in both the real and reciprocal spaces. The proposed experiments include a neutron reflectometry experiment to measure the precise Q-dependence of the structure factor of the vortex lattice in the Bragg glass state. A second set of SANS experiments will be on a shear-strained Nb single crystal for testing a recently proposed theory of the stability of Bragg glass. The objective is to artificially create a set of parallel grain boundaries into a Nb single crystal and use SANS to measure the vortex matter diffraction pattern as a function of the changing angle between the applied magnetic field to the grain boundaries. The intrinsic merits of the proposed work are a new fundamental understanding of type-II superconductors on which superconducting technology is based, and a firm understanding of phases and phase transitions in condensed matter systems with random pinning. The broader impact of the program includes the training of future generation of neutron scientists, and further development of neutron scattering and complementary techniques for studies of superconducting materials. The graduate and undergraduate students participating in this project will learn the state-of-the-art neutron scattering techniques, acquire a wide range of materials research experiences, and participate in the frontier research of superconductivity. This should best prepare the students for future careers in academia, industry, or government.

  2. Effect of antiferromagnetic layer thickness on exchange bias, training effect, and magnetotransport properties in ferromagnetic/antiferromagnetic antidot arrays

    SciTech Connect (OSTI)

    Gong, W. J.; Liu, W., E-mail: wliu@imr.ac.cn; Feng, J. N.; Zhang, Z. D. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Kim, D. S.; Choi, C. J. [Functional Materials Division, Korea Institute of Materials Science, 531 Changwon- daero, Changwon 631-831 (Korea, Republic of)

    2014-04-07

    The effect of antiferromagnetic (AFM) layer on exchange bias (EB), training effect, and magnetotransport properties in ferromagnetic (FM) /AFM nanoscale antidot arrays and sheet films Ag(10?nm)/Co(8?nm)/NiO(t{sub NiO})/Ag(5?nm) at 10?K is studied. The AFM layer thickness dependence of the EB field shows a peak at t{sub NiO}?=?2?nm that is explained by using the random field model. The misalignment of magnetic moments in the three-dimensional antidot arrays causes smaller decrease of EB field compared with that in the sheet films for training effect. The anomalous magnetotransport properties, in particular positive magnetoresistance (MR) for antidot arrays but negative MR for sheet films are found. The training effect and magnetotransport properties are strongly affected by the three-dimensional spin-alignment effects in the antidot arrays.

  3. New insulating antiferromagnetic quaternary iridates MLa10Ir4O24 (M=Sr, Ba)

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhao, Qingbiao; Han, Fei; Stoumpos, Constantinos C.; Han, Tian -Heng; Li, Hao; Mitchell, J. F.

    2015-07-01

    Recently, oxides of Ir4+ have received renewed attention in the condensed matter physics community, as it has been reported that certain iridates have a strongly spin-orbital coupled (SOC) electronic state, Jeff = ½, that defines the electronic and magnetic properties. The canonical example is the Ruddlesden-Popper compound Sr2IrO4, which has been suggested as a potential route to a new class of high temperature superconductor due to the formal analogy between Jeff = ½ and the S = ½ state of the cuprate superconductors. The quest for other iridium oxides that present tests of the underlying SOC physics is underway. Inmore »this spirit, here we report the synthesis and physical properties of two new quaternary tetravalent iridates, MLa10Ir4O24 (M = Sr, Ba). The crystal structure of both compounds features isolated IrO6 octahedra in which the electronic configuration of Ir is d5. As a result, both compounds order antiferromagnetically despite the lack of obvious superexchange pathways, and resistivity measurement shows that SrLa10Ir4O24 is an insulator.« less

  4. Valence Bond States: Link models

    E-Print Network [OSTI]

    E. Rico; R. Hübener; S. Montangero; N. Moran; B. Pirvu; J. Vala; H. J. Briegel

    2009-08-07

    An isotropic anti-ferromagnetic quantum state on a square lattice is characterized by symmetry arguments only. By construction, this quantum state is the result of an underlying valence bond structure without breaking any symmetry in the lattice or spin spaces. A detailed analysis of the correlations of the quantum state is given (using a mapping to a 2D classical statistical model and methods in field theory like mapping to the non-linear sigma model or bosonization techniques) as well as the results of numerical treatments (regarding exact diagonalization and variational methods). Finally, the physical relevance of the model is motivated. A comparison of the model to known anti-ferromagnetic Mott-Hubbard insulators is given by means of the two-point equal-time correlation function obtained i) numerically from the suggested state and ii) experimentally from neutron scattering on cuprates in the anti-ferromagnetic insulator phase.

  5. Evidence of exchange bias effect originating from the interaction between antiferromagnetic core and spin glass shell

    SciTech Connect (OSTI)

    Zhang, X. K., E-mail: zhangxianke77@163.com; Yuan, J. J.; Yu, H. J.; Zhu, X. R.; Xie, Y. M. [School of Physics and Electronics, Institute of Optoelectronic Materials and Technology, Gannan Normal University, Ganzhou 341000 (China); Tang, S. L.; Xu, L. Q. [Nanjing National Laboratory of Microstructures, College of Physics, Nanjing University, Nanjing 210093 (China)

    2014-07-14

    Spin glass behavior and exchange bias effect have been observed in antiferromagnetic SrMn{sub 3}O{sub 6?x} nanoribbons synthesized via a self-sacrificing template process. The magnetic field dependence of thermoremanent magnetization and isothermal remanent magnetization shows that the sample is good correspondence to spin glass and diluted antiferromagnetic system for the applied field H??2?T, respectively. By detailed analysis of training effect using Binek's model, we argue that the observed exchange bias effect in SrMn{sub 3}O{sub 6?x} nanoribbons arises entirely from an interface exchange coupling between the antiferromagnetic core and spin glass shell. The present study is useful for understanding the nature of shell layer and the origin of exchange bias effect in other antiferromagnetic nanosystems as well.

  6. Strings, vortex rings, and modes of instability

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Gubser, Steven S.; Nayar, Revant; Parikh, Sarthak

    2015-03-01

    We treat string propagation and interaction in the presence of a background Neveu–Schwarz three-form field strength, suitable for describing vortex rings in a superfluid or low-viscosity normal fluid. A circular vortex ring exhibits instabilities which have been recognized for many years, but whose precise boundaries we determine for the first time analytically in the small core limit. Two circular vortices colliding head-on exhibit stronger instabilities which cause splitting into many small vortices at late times. We provide an approximate analytic treatment of these instabilities and show that the most unstable wavelength is parametrically larger than a dynamically generated length scalemore »which in many hydrodynamic systems is close to the cutoff. We also summarize how the string construction we discuss can be derived from the Gross–Pitaevskii Lagrangian, and also how it compares to the action for giant gravitons.« less

  7. Stabilization of three-wave vortex beams in the waveguide

    E-Print Network [OSTI]

    Gammal, Arnaldo

    2015-01-01

    We consider two-dimensional (2D) localized vortical modes in the three-wave system with the quadratic ($\\chi ^{(2)}$) nonlinearity, alias nondegenerate second-harmonic-generating system, guided by the isotropic harmonic-oscillator (HO) (alias parabolic) confining potential. In addition to the straightforward realization in optics, the system models mixed atomic-molecular Bose-Einstein condensates (BECs). The main issue is stability of the vortex modes, which is investigated through computation of instability growth rates for eigenmodes of small perturbations, and by means of direct simulations. The threshold of parametric instability for single-color beams, represented solely by the second harmonic (SH) with zero vorticity, is found in an analytical form with the help of the variational approximation (VA). Trapped states with vorticities $\\left( +1,-1,0\\right) $ in the two fundamental-frequency (FF) components and the SH one [the so-called \\textit{hidden-vorticity} (HV) modes] are completely unstable. Also un...

  8. Energy harvesting using vortex-induced vibrations of tensioned cables

    E-Print Network [OSTI]

    Grouthier, Clement; de Langre, Emmanuel

    2012-01-01

    The development of energy harvesting systems based on fluid/structure interactions is part of the global search for innovative tools to produce renewable energy. In this paper, the possibility to harvest energy from a flow using vortex-induced vibrations (VIV) of a tensioned flexible cable is analyzed. The fluid loading on the vibrating solid and resulting dynamics are computed using an appropriate wake-oscillator model, allowing one to perform a systematic parametric study of the efficiency. The generic case of an elastically-mounted rigid cylinder is first investigated, before considering an infinite cable with two different types of energy harvesting : a uniformly spanwise distributed harvesting and then a periodic distribution of discrete harvesting devices. The maximum harvesting efficiency is of the same order for each configuration and is always reached when the solid body and its wake are in a frequency lock-in state.

  9. Origin and dynamics of vortex rings in drop splashing

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Lee, Ji San; Park, Su Ji; Lee, Jun Ho; Weon, Byung Mook; Fezzaa, Kamel; Je, Jung Ho

    2015-09-04

    A vortex is a flow phenomenon that is very commonly observed in nature. More than a century, a vortex ring that forms during drop splashing has caught the attention of many scientists due to its importance in understanding fluid mixing and mass transport processes. However, the origin of the vortices and their dynamics remain unclear, mostly due to the lack of appropriate visualization methods. Here, with ultrafast X-ray phase-contrast imaging, we show that the formation of vortex rings originates from the energy transfer by capillary waves generated at the moment of the drop impact. Interestingly, we find a row ofmore »vortex rings along the drop wall, as demonstrated by a phase diagram established here, with different power-law dependencies of the angular velocities on the Reynolds number. These results provide important insight that allows understanding and modelling any type of vortex rings in nature, beyond just vortex rings during drop splashing.« less

  10. Vortex Bubble Formation in Pair Plasmas

    E-Print Network [OSTI]

    Berezhiani, V I; Mahajan, S M; Aleksi?, B N

    2013-01-01

    It is shown that delocalized vortex solitons in relativistic pair plasmas with small temperature asymmetries can be unstable for intermediate intensities of the background electromagnetic field. Instability leads to the generation of ever-expanding cavitating bubbles in which the electromagnetic fields are zero. The existence of such electromagnetic bubbles is demonstrated by qualitative arguments based on a hydrodynamic analogy, and by numerical solutions of the appropriate Nonlinear Schr\\"odinger equation with a saturating nonlinearity.

  11. Liquid Vortex Shielding for Fusion Energy Applications

    SciTech Connect (OSTI)

    Bardet, Philippe M. [University of California, Berkeley (United States); Supiot, Boris F. [University of California, Berkeley (United States); Peterson, Per F. [University of California, Berkeley (United States); Savas, Oemer [University of California, Berkeley (United States)

    2005-05-15

    Swirling liquid vortices can be used in fusion chambers to protect their first walls and critical elements from the harmful conditions resulting from fusion reactions. The beam tube structures in heavy ion fusion (HIF) must be shielded from high energy particles, such as neutrons, x-rays and vaporized coolant, that will cause damage. Here an annular wall jet, or vortex tube, is proposed for shielding and is generated by injecting liquid tangent to the inner surface of the tube both azimuthally and axially. Its effectiveness is closely related to the vortex tube flow properties. 3-D particle image velocimetry (PIV) is being conducted to precisely characterize its turbulent structure. The concept of annular vortex flow can be extended to a larger scale to serve as a liquid blanket for other inertial fusion and even magnetic fusion systems. For this purpose a periodic arrangement of injection and suction holes around the chamber circumference are used, generating the layer. Because it is important to match the index of refraction of the fluid with the tube material for optical measurement like PIV, a low viscosity mineral oil was identified and used that can also be employed to do scaled experiments of molten salts at high temperature.

  12. Electron vortex orbits and merger T. B. Mitchella)

    E-Print Network [OSTI]

    California at San Diego, University of

    of the spatially extended vortices are calculated by the point vortex approximation, and simple rules are used resulted in predictions for tim

  13. High antiferromagnetic transition temperature of a honeycomb compound SrRu2O6

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Tian, Wei; Svoboda, Chris; Ochi, M.; Matsuda, M.; Cao, Huibo; Cheng, J. -G.; Sales, B. C.; Mandrus, D.; Arita, R.; Trivedi, Nandini; et al

    2015-09-14

    We study the high-temperature magnetic order in a quasi-two-dimensional honeycomb compound SrRu2O6 by measuring magnetization and neutron powder diffraction with both polarized and unpolarized neutrons. SrRu2O6 crystallizes into the hexagonal lead antimonate (PbSb2O6, space group P31m) structure with layers of edge-sharing RuO6 octahedra separated by Sr2+ ions. SrRu2O6 is found to order at TN = 565 K with Ru moments coupled antiferromagnetically both in plane and out of plane. The magnetic moment is 1.30(2) ?B/Ru at room temperature and is along the crystallographic c axis in the G-type magnetic structure. We perform density functional calculations with constrained random-phase approximation (RPA)more »to obtain the electronic structure and effective intra- and interorbital interaction parameters. The projected density of states shows strong hybridization between Ru 4d and O 2p. By downfolding to the target t2g bands we extract the effective magnetic Hamiltonian and perform Monte Carlo simulations to determine the transition temperature as a function of interand intraplane couplings. We find a weak interplane coupling, 3% of the strong intraplane coupling, permits three-dimensional magnetic order at the observed TN .« less

  14. Field induced spin density wave and spiral phases in a layered antiferromagnet

    SciTech Connect (OSTI)

    Stone, Matthew B.; Lumsden, Mark D.; Garlea, Vasile O.; Grenier, B.; Ressouche, E.; Samulon, Eric C.; Fisher, Ian R.

    2015-07-28

    We determine the low-field ordered magnetic phases of the S=1 dimerized antiferromagnet Ba3Mn2O8 using single crystal neutron diffraction. We find that for magnetic fields between ?0H=8.80 T and 10.56 T applied along the [1\\bar{1}0] direction the system exhibits spin density wave order with incommensurate wave vectors of type (?,?,?). For ?0H > 10.56 T, the magnetic order changes to a spiral phase with incommensurate wave vectors only along the [hh0] direction. For both field induced ordered phases, the magnetic moments are lying in the plane perpendicular to the field direction. The nature of these two transitions is fundamentally different: the low-field transition is a second order transition to a spin-density wave ground state, while the one at higher field, toward the spiral phase, is of first order.

  15. Dual vortex theory of strongly interacting electrons: A non-Fermi...

    Office of Scientific and Technical Information (OSTI)

    Dual vortex theory of strongly interacting electrons: A non-Fermi liquid with a twist Citation Details In-Document Search Title: Dual vortex theory of strongly interacting...

  16. Emergence of nonuniform V-states by synchronization L. Friedland

    E-Print Network [OSTI]

    Friedland, Lazar

    Emergence of nonuniform V-states by synchronization L. Friedland Racah Institute of Physics, Hebrew nonuniform V-states can emerge in both free and bounded space by subjecting an axisymmetric vortex azimuthal symmetry. The cap- ture is followed by adiabatic deformation of the vortex boundary and emergence

  17. Almost Optimal Convergence of the Point Vortex Method for Vortex Sheets using Numerical Filtering

    E-Print Network [OSTI]

    Ferguson, Thomas S.

    vortices, numerical filtering, discrete Cauchy­Kowalewski theorem. AMS subject classifications: primary 65M subsequent modes will be dominated by roundoff error. Since these highest modes are amplified the fastest, singularity formation appears to be generic, even for vortex sheets initially near equilibrium [13, 6, 19

  18. One-vortex moduli space and Ricci flow

    E-Print Network [OSTI]

    Nicholas S. Manton

    2008-05-02

    The metric on the moduli space of one abelian Higgs vortex on a surface has a natural geometrical evolution as the Bradlow parameter, which determines the vortex size, varies. It is shown by various arguments, and by calculations in special cases, that this geometrical flow has many similarities to Ricci flow.

  19. High-Resolution Simulations of Parallel BladeVortex Interactions

    E-Print Network [OSTI]

    Alonso, Juan J.

    to that encountered in the simulation of realistic helicopter blade­vortex interaction, but the computational costs aeroacoustics rotor tests [2,3]. These tests were performed on a Mach-scaled Bo-105 rotor and the blade loadsHigh-Resolution Simulations of Parallel Blade­Vortex Interactions Alasdair Thom University

  20. Finned Tube With Vortex Generators For A Heat Exchanger.

    DOE Patents [OSTI]

    Sohal, Manohar S. (Idaho Falls, ID); O'Brien, James E. (Idaho Falls, ID)

    2005-12-20

    A system for and method of manufacturing a finned tube for a heat exchanger is disclosed herein. A continuous fin strip is provided with at one pair of vortex generators. A tube is rotated and linearly displaced while the continuous fin strip with vortex generators is spirally wrapped around the tube.

  1. Finned Tube With Vortex Generators For A Heat Exchanger.

    DOE Patents [OSTI]

    Sohal, Monohar S. (Idaho Falls, ID); O'Brien, James E. (Idaho Falls, ID)

    2004-09-14

    A system for and method of manufacturing a finned tube for a heat exchanger is disclosed herein. A continuous fin strip is provided with at least one pair of vortex generators. A tube is rotated and linearly displaced while the continuous fin strip with vortex generators is spirally wrapped around the tube.

  2. Disordering transitions in vortex matter: peak effect and phase diagram

    E-Print Network [OSTI]

    Scalettar, Richard T.

    Disordering transitions in vortex matter: peak effect and phase diagram C.J. Olson a,*, C- order nature of this transition. In YBCO a rapid increase in Jc as a function of magnetic field vortex phase diagram as a function of magnetic field and temperature. For increasing field or temperature

  3. Vortex Lattice Modelling of Winglets on Wind Turbine Blades

    E-Print Network [OSTI]

    Vortex Lattice Modelling of Winglets on Wind Turbine Blades Mads Døssing Risø-R-1621(EN) Risø Title: Vortex Lattice Modelling of Winglets on Wind Turbine Blades Departments: Wind Energy Department turbines can be increased by the use of winglets without increasing the swept area. This makes them

  4. Dynamics of Magnetized Vortex Tubes in the Solar Chromosphere

    E-Print Network [OSTI]

    Kitiashvili, I N; Mansour, N N; Wray, A A

    2012-01-01

    We use 3D radiative MHD simulations to investigate the formation and dynamics of small-scale (less than 0.5 Mm in diameter) vortex tubes spontaneously generated by turbulent convection in quiet-Sun regions with initially weak mean magnetic fields. The results show that the vortex tubes penetrate into the chromosphere and substantially affect the structure and dynamics of the solar atmosphere. The vortex tubes are mostly concentrated in intergranular lanes and are characterized by strong (near sonic) downflows and swirling motions that capture and twist magnetic field lines, forming magnetic flux tubes that expand with height and which attain magnetic field strengths ranging from 200 G in the chromosphere to more than 1 kG in the photosphere. We investigate in detail the physical properties of these vortex tubes, including thermodynamic properties, flow dynamics, and kinetic and current helicities, and conclude that magnetized vortex tubes provide an important path for energy and momentum transfer from the con...

  5. Dynamic selective switching in antiferromagnetically-coupled bilayers close to the spin reorientation transition

    SciTech Connect (OSTI)

    Fernández-Pacheco, A., E-mail: af457@cam.ac.uk; Mansell, R.; Petit, D.; Lee, J. H.; Cowburn, R. P. [Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Ummelen, F. C.; Swagten, H. J. M. [Department of Applied Physics, Center for NanoMaterials, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands)

    2014-09-01

    We have designed a bilayer synthetic antiferromagnet where the order of layer reversal can be selected by varying the sweep rate of the applied magnetic field. The system is formed by two ultra-thin ferromagnetic layers with different proximities to the spin reorientation transition, coupled antiferromagnetically using Ruderman-Kittel-Kasuya-Yosida interactions. The different dynamic magnetic reversal behavior of both layers produces a crossover in their switching fields for field rates in the kOe/s range. This effect is due to the different effective anisotropy of both layers, added to an appropriate asymmetric antiferromagnetic coupling between them. Field-rate controlled selective switching of perpendicular magnetic anisotropy layers as shown here can be exploited in sensing and memory applications.

  6. Multistage interaction of a shock wave and a strong vortex Shuhai Zhanga

    E-Print Network [OSTI]

    Zhang, Yong-Tao

    tube, it traveled back toward the vortex and the interaction between the shock and the vortex tookMultistage interaction of a shock wave and a strong vortex Shuhai Zhanga China Aerodynamics; published online 8 November 2005 The interaction between a shock wave and a strong vortex is simulated

  7. Interface Coupling Transition in a Thin EpitaxialAntiferromagnetic Film Interacting with a Ferromagnetic Substrate

    SciTech Connect (OSTI)

    Finazzi, M.; Brambilla, A.; Biagioni, P.; Graf, J.; Gweon, G.-H.; Scholl, A.; Lanzara, A.; Duo, L.

    2006-09-07

    We report experimental evidence for a transition in theinterface coupling between an antiferromagnetic film and a ferromagneticsubstrate. The transition is observed in a thin epitaxial NiO film grownon top of Fe(001) as the film thickness is increased. Photoemissionelectron microscopy excited with linearly polarized x rays shows that theNiO film is antiferromagnetic at room temperature with in-plane uniaxialmagnetic anisotropy. The anisotropy axis is perpendicular to the Fesubstrate magnetization when the NiO thickness is less than about 15A,but rapidly becomes parallel to the Fe magnetization for a NiO coveragehigher than 25 A.

  8. Rotor spectra, berry phases, and monopole fields: From antiferromagnets to QCD

    SciTech Connect (OSTI)

    Chandrasekharan, S.; Jiang, F.-J.; Wiese, U.-J.; Pepe, M.

    2008-10-01

    The order parameter of a finite system with a spontaneously broken continuous global symmetry acts as a quantum mechanical rotor. Both antiferromagnets with a spontaneously broken SU(2){sub s} spin symmetry and massless QCD with a broken SU(2){sub L}xSU(2){sub R} chiral symmetry have rotor spectra when considered in a finite volume. When an electron or hole is doped into an antiferromagnet or when a nucleon is propagating through the QCD vacuum, a Berry phase arises from a monopole field and the angular momentum of the rotor is quantized in half-integer units.

  9. The effect of stoichiometry on vortex flame interactions

    SciTech Connect (OSTI)

    Bell, John B.; Brown, Nancy J.; Day, Marcus S.; Frenklach, Michael; Grcar, Joseph F.; Tonse, Shaheen R.

    1999-12-01

    The interaction of a vortex pair with a premixed flame serves as an important prototype for premixed turbulent combustion. In this study, the authors investigate the interaction of a counter-rotating vortex pair with an initially flat premixed methane flame. The authors focus on characterizing the mechanical nature of the flame-vortex interaction and on the features of the interaction strongly affected by fuel equivalence ratio. The authors compare computational solutions obtained using a time-dependent, two-dimensional adaptive low Mach number combustion algorithm that incorporates GRI-Mech 1.2 for the chemistry, thermodynamics and transport of the chemical species. The authors find that the circulation around the vortex scours gas from the preheat zone in front of the flame, making the interaction extremely sensitive to equivalence ratio. For nearly stoichiometric cases, the peak mole fraction of CH across the flame is relatively insensitive to the vortex whereas for richer flames they observe a substantial and rapid decline in the peak CH mole fraction, commencing early in the flame-vortex interaction. The peak concentration of HCO is found to correlate, in both space and time, with the peak heat release across a broad range of equivalence ratios. The model also predicts a measurable increase in C{sub 2}H{sub 2} as a result of interaction with the vortex, and a marked increase in the low temperature chemistry activity.

  10. Crystalline Scaling Geometries from Vortex Lattices

    E-Print Network [OSTI]

    Ning Bao; Sarah Harrison

    2013-06-25

    We study magnetic geometries with Lifshitz and/or hyperscaling violation exponents (both with a hard wall cutoff in the IR and a smooth black brane horizon) which have a complex scalar field which couples to the magnetic field. The complex scalar is unstable to the production of a vortex lattice in the IR. The lattice is a normalizable mode which is relevant (i.e. grows into the IR.) When one considers linearized backreaction of the lattice on the metric and gauge field, the metric forms a crystalline structure. We analyze the scaling of the free energy, thermodynamic entropy, and entanglement in the lattice phase and find that in the smeared limit, the leading order correction to thermodynamic properties due to the lattice has the scaling behavior of a theory with a hyperscaling violation exponent between 0 and 1, indicating a flow to an effectively lower-dimensional theory in the deep IR.

  11. Fuel injection of coal slurry using vortex nozzles and valves

    DOE Patents [OSTI]

    Holmes, Allen B. (Rockville, MD)

    1989-01-01

    Injection of atomized coal slurry fuel into an engine combustion chamber is achieved at relatively low pressures by means of a vortex swirl nozzle. The outlet opening of the vortex nozzle is considerably larger than conventional nozzle outlets, thereby eliminating major sources of failure due to clogging by contaminants in the fuel. Control fluid, such as air, may be used to impart vorticity to the slurry and/or purge the nozzle of contaminants during the times between measured slurry charges. The measured slurry charges may be produced by a diaphragm pump or by vortex valves controlled by a separate control fluid. Fluidic circuitry, employing vortex valves to alternatively block and pass cool slurry fuel flow, is disclosed.

  12. Structural distortions in the spin-gap regime of the quantum antiferromagnet SrCu{sub 2}(BO{sub 3}){sub 2}

    SciTech Connect (OSTI)

    Vecchini, C.; Adamopoulos, O.; Chapon, L.C.; Lappas, A.; Kageyama, H.; Ueda, Y.; Zorko, A.

    2009-12-15

    We report the first crystallographic study within the low-temperature (<40 K) spin-gap region of the two-dimensional frustrated antiferromagnet SrCu{sub 2}(BO{sub 3}){sub 2}. The crystal system does not deviate from the tetragonal I-42m space group symmetry. However, our high-resolution neutron powder diffraction measurements uncover subtle structural modifications below 34 K, concomitant to the formation of the dimer singlet ground state. Intimate spin-lattice coupling leads to negative thermal expansion of the tetragonal structure, which reflects into particular local lattice adjustments. The extracted structural parameters suggest the reduction of the buckling found in the copper-borate planes and the strengthening of the leading, in-plane intra-dimer superexchange interaction. The observed contraction along the c-axis, associated with the inter-dimer exchange in adjacent layers, indicates the involvement of weaker three-dimensional interactions in the magnetic properties. The rules posed by the crystal symmetry do not preclude Dzyaloshinsky-Moriya interactions, which therefore remain as an important source of spin anisotropy necessary to rationalise the ground state behaviour. - Abstract: We report the first crystallographic study within the low-temperature spin-gap region of the two-dimensional frustrated antiferromagnet SrCu{sub 2}(BO{sub 3}){sub 2}. Subtle spin-lattice coupling was unveiled in the low-temperature region. Display Omitted

  13. Riemannian geometrical constraints on magnetic vortex filaments in plasmas

    E-Print Network [OSTI]

    L. C. Garcia de Andrade

    2005-10-16

    Two theorems on the Riemannian geometrical constraints on vortex magnetic filaments acting as dynamos in (MHD) flows are presented. The use of Gauss-Mainard-Codazzi equations allows us to investigate in detail the influence of curvature and torsion of vortex filaments in the MHD dynamos. This application follows closely previous applications to Heisenberg spin equation to the investigations in magnetohydrostatics given by Schief (Plasma Physics J. 10, 7, 2677 (2003)). The Lorentz force on vortex filaments are computed and the ratio between the forces along different directions are obtained in terms of the ratio between the corresponding magnetic fields which equals also the ratio between the Frenet torsion and vortex line curvature. A similar relation between Lorentz forces, magnetic fields and twist, which is proportional to total torsion integral has been obtained by Ricca (Fluid Dyn. Res. 36,319 (2005)) in the case of inflexional desiquilibrium of magnetic flux-tubes. This is due to the fact that the magnetic vortex lines are a limit case of the magnetic flux-tubes when the lenght of the tube is much greater than the radius of the tube. Magnetic helicity equation of the filament allows us again to determine the magnetic fields ratio from Frenet curvature and torsion of the vortex lines.

  14. Pressure and magnetic field dependence of the antiferromagnetism of PrFe sub 4 P sub 12

    SciTech Connect (OSTI)

    Kuric, M.V.; Guertin, R.P. ); Torikachvili, M.S. ); Maple, M.B. ); Foner, S. )

    1990-05-01

    The compound PrFe{sub 4}P{sub 12}, which has the cubic LaFe{sub 4}P{sub 12} modified CoAs{sub 3}-type structure, orders antiferromagnetically, with {ital T}{sub {ital N}}=6.2 K and with several field-induced magnetic transitions for {ital T}{lt}{ital T}{sub {ital N}}, up to 5 T for {ital T}{much lt}{ital T}{sub {ital N}}. Heat capacity measurements show the transition is a bulk effect, with magnetic entropy consistent with a magnetic doublet or triplet crystal-field ground state. dc magnetization measurements, {ital M}({ital H}), at {ital T}=4.2 K up to 23 T reveal no further field-induced transitions, and {ital M}({ital H}) attains only 54% of the Pr{sup 3+} free-ion moment at highest fields. Pulsed field measurements of {ital dM}/{ital dH} at 4.2 K up to 45 T fail to resolve further transitions. The transition to the antiferromagnetic state is accompanied by a very sharp Suezaki--Mori-type electrical resistivity transition due to critical scattering of electrons by spin fluctuations. Hydrostatic pressure decreases {ital T}{sub {ital N}}, ({ital dT}{sub {ital N}}/{ital dP}={minus}0.11 K/kbar), in sharp contrast to the behavior for the isomorphic semiconducting ferromagnet, UFe{sub 4}P{sub 12} ({ital T}{sub {ital C}}=3.15 K; {ital dT}{sub {ital C}}/{ital dP}=+0.26 K/kbar). The field-induced magnetic transitions are also sharply reduced with pressure. The pressure dependence of the electrical resistivity showed a decrease in {ital T}{sub {ital N}}, with a concomitant decrease in the size of the Suezaki--Mori anomaly. The results are discussed in terms of crystal-field splittings of the Pr ion and possible hybridization effects.

  15. Alleviation of fuselage form drag using vortex flows: Final report

    SciTech Connect (OSTI)

    Wortman, A.

    1987-09-15

    The concept of using vortex generators to reduce the fuselage form drag of transport aircraft combines the outflow from the plane of symmetry which is induced by the rotational component of the vortex flow with the energization of the boundary layer to reduce the momentum thickness and to delay or eliminate flow separation. This idea was first advanced by the author in 1981. Under a DOE grant, the concept was validated in wind tunnel tests of approximately 1:17 scale models of fuselages of Boeing 747 and Lockheed C-5 aircraft. The search for the minimum drag involved three vortex generator configurations with three sizes of each in six locations clustered in the aft regions of the fuselages at the beginning of the tail upsweep. The local Reynolds number, which is referred to the length of boundary layer run from the nose, was approximately 10{sup 7} so that a fully developed turbulent boundary layer was present. Vortex generator planforms ranged from swept tapered, through swept straight, to swept reverse tapered wings whose semi-spans ranged from 50% to 125% of the local boundary layer thickness. Pitch angles of the vortex generators were varied by inboard actuators under the control of an external proportional digital radio controller. It was found that certain combinations of vortex generator parameters increased drag. However, with certain configurations, locations, and pitch angles of vortex generators, the highest drag reductions were 3% for the 747 and about 6% for the C-5, thus confirming the arguments that effectiveness increases with the rate of upsweep of the tail. Greatest gains in performance are therefore expected on aft loading military transports. 10 refs., 11 figs., 1 tab.

  16. Vortex and structural dynamics of a flexible cylinder in cross-flow

    SciTech Connect (OSTI)

    Shang, Jessica K., E-mail: jshang@princeton.edu; Stone, Howard A. [Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544 (United States); Smits, Alexander J. [Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544 (United States); Monash University, VIC 3800 (Australia)

    2014-05-15

    A low-density, flexible cantilevered cylinder was permitted to vibrate freely under the influence of vortex shedding in the laminar flow regime. We find that the vortex-induced vibrations (VIV) of a flexible cantilever depart from those of a flexible cylinder that is fixed at both ends. In particular, we find discontinuous regions of VIV behavior – here called states – as a function of the reduced velocity U{sup *}. These states are demarcated by discrete changes in the dominant eigenmodes of the structural response as the cylinder vibrates in progressively higher structural modes with increasing U{sup *}. The contribution of structural modes can be identified readily by a modal projection of the cylinder oscillation onto known cantilever beam modes. Oscillation frequencies do not monotonically increase with U{sup *}. The wake response between different states is also found to have distinct characteristics; of particular note is the occurrence of a P+S wake over one of these regions, which is associated with a high-amplitude vibration of the cylinder that is due to the constructive interference of contributing eigenmodes.

  17. Exchange Bias Driven by the Dzyaloshinskii-Moriya Interaction and Ferroelectric Polarization at G-Type Antiferromagnetic Perovskite Interfaces

    E-Print Network [OSTI]

    Tennessee, University of

    -Type Antiferromagnetic Perovskite Interfaces Shuai Dong,1,2,3 Kunihiko Yamauchi,4 Seiji Yunoki,5,6 Rong Yu,1,2 Shuhua interaction and ferroelectric polarization, for the explanation of exchange bias effects in perovskites

  18. Spin-orbit torques in ferromagnets and antiferromagnets 

    E-Print Network [OSTI]

    Gao, Huawei

    2015-06-10

    Spintronics is a sub-field of condensed matter physics which explores the physics of electrons involving both their charge and spin, with an emphasis on the active manipulation of the spin degree of freedom in solid state systems. In spin...

  19. Systematic low-energy effective field theory for electron-doped antiferromagnets

    SciTech Connect (OSTI)

    Bruegger, C.; Kaempfer, F.; Moser, M.; Wiese, U.-J.; Hofmann, C. P.; Pepe, M.

    2007-06-01

    In contrast to hole-doped systems which have hole pockets centered at ({+-}({pi}/2a),{+-}({pi}/2a)), in lightly electron-doped antiferromagnets the charged quasiparticles reside in momentum space pockets centered at (({pi}/a),0) or (0,({pi}/a)). This has important consequences for the corresponding low-energy effective field theory of magnons and electrons which is constructed in this paper. In particular, in contrast to the hole-doped case, the magnon-mediated forces between two electrons depend on the total momentum P-vector of the pair. For P-vector=0, the one-magnon exchange potential between two electrons at distance r is proportional to 1/r{sup 4}, while in the hole case, it has a 1/r{sup 2} dependence. The effective theory predicts that spiral phases are absent in electron-doped antiferromagnets.

  20. Vortex in a relativistic perfect isentropic fluid and Nambu Goto dynamics

    E-Print Network [OSTI]

    B. Boisseau

    1999-11-26

    By a weak deformation of the cylindrical symmetry of the potential vortex in a relativistic perfect isentropic fluid, we study the possible dynamics of the central line of this vortex. In "stiff" material the Nanbu-Goto equations are obtained

  1. Vortex life cycles in two-and three-layer quasi-geostrophic models 

    E-Print Network [OSTI]

    Fox, Amanda Katherine

    2000-01-01

    regimes with jets has occurred. This research attempted to first determine the typical lifetime of a vortex, with considerations of its birth, evolution, and cessation. A vortex census was also performed in an attempt to describe the life cycle...

  2. Wave–vortex interactions in the nonlinear Schrödinger equation

    SciTech Connect (OSTI)

    Guo, Yuan Bühler, Oliver

    2014-02-15

    This is a theoretical study of wave–vortex interaction effects in the two-dimensional nonlinear Schrödinger equation, which is a useful conceptual model for the limiting dynamics of superfluid quantum condensates at zero temperature. The particular wave–vortex interaction effects are associated with the scattering and refraction of small-scale linear waves by the straining flows induced by quantized point vortices and, crucially, with the concomitant nonlinear back-reaction, the remote recoil, that these scattered waves exert on the vortices. Our detailed model is a narrow, slowly varying wavetrain of small-amplitude waves refracted by one or two vortices. Weak interactions are studied using a suitable perturbation method in which the nonlinear recoil force on the vortex then arises at second order in wave amplitude, and is computed in terms of a Magnus-type force expression for both finite and infinite wavetrains. In the case of an infinite wavetrain, an explicit asymptotic formula for the scattering angle is also derived and cross-checked against numerical ray tracing. Finally, under suitable conditions a wavetrain can be so strongly refracted that it collapses all the way onto a zero-size point vortex. This is a strong wave–vortex interaction by definition. The conditions for such a collapse are derived and the validity of ray tracing theory during the singular collapse is investigated.

  3. Temperature dependence of anisotropic magnetoresistance in antiferromagnetic Sr{sub 2}IrO{sub 4}

    SciTech Connect (OSTI)

    Wang, C.; Seinige, H.; Tsoi, M.; Cao, G.; Zhou, J.-S.; Goodenough, J. B.

    2015-05-07

    Temperature-dependent magnetotransport properties of the antiferromagnetic semiconductor Sr{sub 2}IrO{sub 4} are investigated with point-contact devices. The point-contact technique allows to probe very small volumes and, therefore, to look for electronic transport on a microscopic scale. Point-contact measurements with single crystals of Sr{sub 2}IrO{sub 4} were intended to see whether the additional local resistance associated with a small contact area between a sharpened Cu tip and the antiferromagnet shows magnetoresistance (MR) such as that seen in bulk crystals. Point-contact measurements at liquid nitrogen temperature revealed large MRs (up to 28%) for modest magnetic fields (250?mT) applied within an IrO{sub 2} (ab) plane with angular dependence showing a crossover from four-fold to two-fold symmetry with an increasing magnetic field. Point contact measurement exhibits distinctive anisotropic magnetoresistance (AMR) in comparison to a bulk experiment, imposing intriguing questions about the mechanism of AMR in this material. Temperature-dependent MR measurements show that the MR falls to zero at the Neel temperature, but the temperature dependence of the MR ratio differs qualitatively from that of the resistivity. This AMR study helps to unveil the entanglement between electronic transport and magnetism in Sr{sub 2}IrO{sub 4} while the observed magnetoresistive phenomena can be potentially used to sense the antiferromagnetic order parameter in spintronic applications.

  4. The Effects of Wind Tunnel Walls on the Near-field Behavior of a Wingtip Vortex

    E-Print Network [OSTI]

    Hu, Hui

    /vortex interaction on helicopter blades can impact performance and cause undesirable noise and vibration. Vortex completely. This method was applied to investigate the effects of the angle of attack of the test wing vortex structures on dynamics of towed vehicles, tail buffeting, and icing arrays. Blade

  5. Vortex Rings in Bio-inspired and Biological Jet Propulsion Paul S. Krueger1, a

    E-Print Network [OSTI]

    Horth, Lisa

    of the latter, vortex rings are generated by the transient ejection of a jet from a tube or orifice, which leadsVortex Rings in Bio-inspired and Biological Jet Propulsion Paul S. Krueger1, a , Ali A. Moslemi1,b@odu.edu, e wstewart@uci.edu Keywords: Vortex rings, pulsed jets, propulsion, thrust, propulsive efficiency

  6. Vortex pinning in super-conductivity as a rate-independent process

    E-Print Network [OSTI]

    Mielke, Alexander

    : R the magnetic field perpendicular to the plane. The vortex tube density : R is related to ~H via for this case. The modeling assumption in [Cha00] is now that the vortex tubes will not move if the modulus the conservation of the vortex-tube density which is driven by the current J. The second line contains

  7. COLLISIONS OF VORTEX FILAMENT PAIRS VALERIA BANICA, ERWAN FAOU, AND EVELYNE MIOT

    E-Print Network [OSTI]

    Faou, Erwan

    COLLISIONS OF VORTEX FILAMENT PAIRS VALERIA BANICA, ERWAN FAOU, AND EVELYNE MIOT Abstract. We consider the problem of collisions of vortex filaments for a model introduced by Klein, Majda and Damodaran [KMD95] and Zakharov [Z88, Z99] to describe the interaction of almost parallel vortex filaments

  8. Ubiquitous Solar Eruptions Driven by Magnetized Vortex Tubes

    E-Print Network [OSTI]

    Kitiashvili, I N; Lele, S K; Mansour, N N; Wray, A A

    2013-01-01

    The solar surface is covered by high-speed jets transporting mass and energy into the solar corona and feeding the solar wind. The most prominent of these jets have been known as spicules. However, the mechanism initiating these eruptions events is still unknown. Using realistic numerical simulations we find that small-scale eruptions are produced by ubiquitous magnetized vortex tubes generated by the Sun's turbulent convection in subsurface layers. The swirling vortex tubes (resembling tornadoes) penetrate into the solar atmosphere, capture and stretch background magnetic field, and push surrounding material up, generating quasiperiodic shocks. Our simulations reveal a complicated high-speed flow patterns, and thermodynamic and magnetic structure in the erupting vortex tubes. We found that the eruptions are initiated in the subsurface layers and are driven by the high-pressure gradients in the subphotosphere and photosphere, and by the Lorentz force in the higher atmosphere layers.

  9. Optical vortex driven charge current loop and optomagnetism in fullerenes

    E-Print Network [OSTI]

    Wätzel, Jonas; Schäffer, Alexander; Berakdar, Jamal

    2016-01-01

    Endohedral molecular magnets, e.g. as realized in fullerenes containing $\\rm DySc_{2}N$, are promising candidates for molecular electronics and quantum information processing. For their functionalization an ultrafast local magnetization control is essential. Using full ab-initio quantum chemistry calculations we predict the emergence of charge current loops in fullerenes with an associated orbital magnetic moment upon irradiation with weak light vortex pulses that transfer orbital angular momentum. The generated current is controllable by the frequency, the vortex topological charge, and the intensity of the light. Numerical and analytical results show that an ultraviolet vortex femtosecond pulse with an intensity $\\sim10^{13}$ W/cm$^2$ generates non-invasively nA unidirectional surface current with an associated magnetic field of hundreds $\\mu$T at the center of the fullerene.

  10. Low Head, Vortex Induced Vibrations River Energy Converter

    SciTech Connect (OSTI)

    Bernitsas, Michael B.; Dritz, Tad

    2006-06-30

    Vortex Induced Vibrations Aquatic Clean Energy (VIVACE) is a novel, demonstrated approach to extracting energy from water currents. This invention is based on a phenomenon called Vortex Induced Vibrations (VIV), which was first observed by Leonardo da Vinci in 1504AD. He called it ‘Aeolian Tones.’ For decades, engineers have attempted to prevent this type of vibration from damaging structures, such as offshore platforms, nuclear fuel rods, cables, buildings, and bridges. The underlying concept of the VIVACE Converter is the following: Strengthen rather than spoil vortex shedding; enhance rather than suppress VIV; harness rather than mitigate VIV energy. By maximizing and utilizing this unique phenomenon, VIVACE takes this “problem” and successfully transforms it into a valuable resource for mankind.

  11. Small Winding-Number Expansion: Vortex Solutions at Critical Coupling

    E-Print Network [OSTI]

    Keisuke Ohashi

    2015-07-22

    We study an axially symmetric solution of a vortex in the Abelian-Higgs model at critical coupling in detail. Here we propose a new idea for a perturbative expansion of a solution, where the winding number of a vortex is naturally extended to be a real number and the solution is expanded with respect to it around its origin. We test this idea on three typical constants contained in the solution and confirm that this expansion works well with the help of the Pad\\'e approximation. For instance, we analytically reproduce the value of the scalar charge of the vortex with an error of $O(10^{-6})$. This expansion is also powerful even for large winding numbers.

  12. Small Winding-Number Expansion: Vortex Solutions at Critical Coupling

    E-Print Network [OSTI]

    Keisuke Ohashi

    2015-09-01

    We study an axially symmetric solution of a vortex in the Abelian-Higgs model at critical coupling in detail. Here we propose a new idea for a perturbative expansion of a solution, where the winding number of a vortex is naturally extended to be a real number and the solution is expanded with respect to it around its origin. We test this idea on three typical constants contained in the solution and confirm that this expansion works well with the help of the Pad\\'e approximation. For instance, we analytically reproduce the value of the scalar charge of the vortex with an error of $O(10^{-6})$. This expansion is also powerful even for large winding numbers.

  13. Small Winding-Number Expansion: Vortex Solutions at Critical Coupling

    E-Print Network [OSTI]

    Ohashi, Keisuke

    2015-01-01

    We study an axially symmetric solution of a vortex in the Abelian-Higgs model at critical coupling in detail. Here we propose a new idea for a perturbative expansion of a solution, where the winding number of a vortex is naturally extended to be a real number and the solution is expanded with respect to it around its origin. We test this idea on three typical constants contained in the solution and confirm that this expansion works well with the help of the Pad\\'e approximation. For instance, we analytically reproduce the value of the scalar charge of the vortex with an error of $O(10^{-6})$. This expansion is also powerful even for large winding numbers.

  14. Structural and magnetic properties of the Kagome antiferromagnet YbBaCo{sub 4}O{sub 7}

    SciTech Connect (OSTI)

    Huq, A.; Mitchell, J.F. . E-mail: mitchell@anl.gov; Zheng, H.; Chapon, L.C.; Radaelli, P.G.; Knight, K.S.; Stephens, P.W.

    2006-04-15

    The mixed-valent compound YbBaCo{sub 4}O{sub 7} is built up of Kagome sheets of CoO{sub 4} tetrahedra, linked in the third dimension by a triangular layer of CoO{sub 4} tetrahedra in an analogous fashion to that found in the known geometrically frustrated magnets such as pyrochlores and SrCr{sub 9} {sub x} Ga{sub 12-9} {sub x} O{sub 19} (SCGO). We have undertaken a study of the structural and magnetic properties of this compound using combined high-resolution powder neutron and synchrotron X-ray diffraction. YbBaCo{sub 4}O{sub 7} undergoes a first-order trigonal{sup {yields}}orthorhombic phase transition at 175 K. We show that this transition occurs as a response to a markedly underbonded Ba{sup 2+} site in the high-temperature phase and does not appear to involve charge ordering of Co{sup 2+}/Co{sup 3+} ions in the tetrahedra. The symmetry lowering relieves the geometric frustration of the structure, and a long-range-ordered 3-D antiferromagnetic state develops below 80 K.

  15. A Non-Abelian Vortex Lattice in Strongly Coupled Systems

    E-Print Network [OSTI]

    Kenny Wong

    2013-10-09

    The AdS/CFT correspondence predicts that background non-abelian magnetic fields induce instabilities in strongly-coupled systems with non-abelian global symmetries. These instabilities lead to the formation of vortex lattices in which the non-abelian currents "antiscreen" the applied magnetic field. From the bulk perspective, this behaviour can be traced to a well-known instability of Yang-Mills theory. We analyse the phase structure of the instability and comment on aspects of the vortex lattice.

  16. Laboratory Analysis of Vortex Dynamics For Shallow Tidal Inlets 

    E-Print Network [OSTI]

    Whilden, Kerri Ann

    2010-10-12

    OF VORTEX DYNAMICS FOR SHALLOW TIDAL INLETS A Thesis by KERRI ANN WHILDEN Submitted to the O ce of Graduate Studies of Texas A&M University in partial ful llment of the requirements for the degree of MASTER OF SCIENCE August 2009 Major Subject: Ocean... Engineering LABORATORY ANALYSIS OF VORTEX DYNAMICS FOR SHALLOW TIDAL INLETS A Thesis by KERRI ANN WHILDEN Submitted to the O ce of Graduate Studies of Texas A&M University in partial ful llment of the requirements for the degree of MASTER OF SCIENCE Approved...

  17. Experimental investigation of magnetic anisotropy in spin vortex discs

    SciTech Connect (OSTI)

    Garraud, N. Arnold, D. P.

    2014-05-07

    We present experimental 2D vector vibrating sample magnetometer measurements to demonstrate the shape anisotropy effects occurring in micrometer-diameter supermalloy spin vortex discs. Measurements made for different disc sizes and orientations confirm the out-of-plane susceptibility is several orders of magnitude smaller than the in-plane susceptibility. These results validate with a high certitude that spin vortices with high diameter to thickness ratio retain in-plane-only magnetization, even when subjected to fields in the out-of-plane direction. These results contribute to further computational simulations of the dynamics of spin vortex structures in colloidal suspensions where external fields may be applied in any arbitrary direction.

  18. Effect of boundary conditions on axial flow in a concentrated vortex core Richard K. Cohn and Manoochehr M. Koochesfahani

    E-Print Network [OSTI]

    Koochesfahani, Manoochehr M.

    of confined flows such as vortex chambers, and swirl separators (e.g., hydrocyclones). More recently

  19. Investigation of Vortex Structures in Gas-Discharge Nonneutral Electron Plasma: IV. Pulse Ejection of Electrons at the mutual interaction of Vortex Structures

    E-Print Network [OSTI]

    Kervalishvili, N A

    2015-01-01

    The results of experimental investigations of the ejection of electrons from gas-discharge nonneutral electron plasma at interaction of vortex structures have been given. The periodical approach of vortex structures causes the ejection of electrons both from the vortex structures themselves and from the adjacent regions of electron sheath to the end cathodes of discharge device. The ejection takes place in the form of short and long pulses following each other. The nature of these pulses and the dynamics of interaction of vortex structures at their approach were studied.

  20. Elliptic vortex patches: coasts and chaos Andrew Crosby

    E-Print Network [OSTI]

    Lebovitz, Norman

    are important for the transport of heat/salt across the Atlantic and, due to their relatively long life-times (O of such ocean vortices as point vortices and analysing their paths around islands or past coastal gaps presented by Ted were that of motion around a pair of islands (see Figure 2a) where the vortex patch might

  1. -STABILITY AND VORTEX MOTION IN TYPE II SUPERCONDUCTORS

    E-Print Network [OSTI]

    Spirn, Daniel

    -STABILITY AND VORTEX MOTION IN TYPE II SUPERCONDUCTORS MATTHIAS KURZKE AND DANIEL SPIRN Abstract. 1. Introduction 1.1. Physical background. The evolution of a superconducting material is usu- ally of the magnetic field and the electric field potential for a superconducting sample R2 . The parameter

  2. Vortex Rings in a Stratified Fluid M. M. Scase

    E-Print Network [OSTI]

    Dalziel, Stuart

    in a stratified fluid, are developed. These models include both buoyancy forces and the drag due to the generation to investigate the waves generated by the propagation of the vortex ring, the ring is modelled as a sphere, based for describing these wavefronts is given. The drag due to the generated internal wave field is calculated

  3. WAVE-VORTEX INTERACTIONS IN THE ATMOSPHERE, AND CLIMATE

    E-Print Network [OSTI]

    Al Hanbali, Ahmad

    WAVE-VORTEX INTERACTIONS IN THE ATMOSPHERE, AND CLIMATE PREDICTION Onno Bokhove Numerical Analysis, The Netherlands o.bokhove@math.utwente.nl Abstract Can we construct an accurate atmospheric climate model parcel dynamics, linear modes, balan- ced models, gravity waves, weather and climate prediction

  4. Modified Black Hole with Polar Jet and Vortex

    E-Print Network [OSTI]

    T. Tmmalm

    2001-12-06

    There are many models relating an accretion disk of Black Hole to jet outflow. The herein heuristic model describes the continuation of an external accretion disk to an internal accretion disk for less than Black Hole horizon, and subsequent polar jet outflow along polar axis out of polar vortex wherein the event horizon is no longer descriptive.

  5. MOI OF PATTERN FORMATION IN THE VORTEX LANDSCAPE

    E-Print Network [OSTI]

    Wijngaarden, Rinke J.

    1081, 1081 HV Amsterdam, The Netherlands RW@NAT.VU.NL Abstract Due to the occurence of punctuations front were reported by Surdeanu et al.[1]. To local vortex density in the type-II YBa2Cu3O7

  6. Numerical Approximation of Vortex Density Evolution in a Superconductor.

    E-Print Network [OSTI]

    Styles, Vanessa

    Numerical Approximation of Vortex Density Evolution in a Superconductor. C.M. Elliott & V. Styles Abstract A #12;nite volume/element approximation of a mean #12;eld model of superconducting vortices in one approximations of a two-dimensional version of the mean #12;eld model of superconducting vortices considered

  7. Planet Embryos in Vortex Wombs Joseph A. Barranco

    E-Print Network [OSTI]

    Marcus, Philip S.

    Planet Embryos in Vortex Wombs Joseph A. Barranco and Philip S. Marcus Dept. of Astronomy gravitating planetesimals, the "build- ing blocks" of planets. One theory is that the dust grains settle into the mid-plane of the protoplane- tary disk (thin, cool disk of gas and dust in orbit around a newly

  8. Biomedical Engineering Correlation Between Vortex Ring Formation and Mitral

    E-Print Network [OSTI]

    Kheradvar, Arash

    was generated during fluid propulsion and that it is maximal for an annulus diameter close to the normal adult typically develop from a jet or slug of fluid ejected from a nozzle. In fluid mechanics, mitral inflow fluid phenomena observed in the left ventricle during diastole is the presence of vortex rings

  9. Vortex stabilized electron beam compressed fusion grade plasma

    SciTech Connect (OSTI)

    Hershcovitch, Ady

    2014-03-19

    Most inertial confinement fusion schemes are comprised of highly compressed dense plasmas. Those schemes involve short, extremely high power, short pulses of beams (lasers, particles) applied to lower density plasmas or solid pellets. An alternative approach could be to shoot an intense electron beam through very dense, atmospheric pressure, vortex stabilized plasma.

  10. VORTEX: Design and Implementation of an Interactive Volumetric Display

    E-Print Network [OSTI]

    Subramanian, Sriram

    VORTEX: Design and Implementation of an Interactive Volumetric Display Abstract True 3D display systems like volumetric displays allow generation of autostereoscopic, multi-view 3D content that has real custom volumetric display from easily available components. By building a touch-enabled volumetric

  11. A holographic model for antiferromagnetic quantum phase transition induced by magnetic field

    E-Print Network [OSTI]

    Rong-Gen Cai; Run-Qiu Yang; F. V. Kusmartsev

    2015-01-19

    We propose a gravity dual of antiferromagnetic quantum phase transition (QPT) induced by magnetic field and study the criticality in the vicinity of quantum critical point (QCP). Results show the boundary critical theory is a strong coupling theory with dynamic exponent $z=2$. The hyperscaling law is violated and logarithmic corrections appear near the QCP. We compare our theoretical results with experimental data on variety of materials including low-dimensional magnet, BiCoPO$_5$ and pyrochlores, Er$_{2-2x}$Y$_{2x}$Ti$_2$O$_7$. Our model describes well the existing experiments and predicts QCP and other high field magnetic properties of these compounds.

  12. Dynamics of Thermal Effects in the Spin-Wave Theory of Quantum Antiferromagnets

    E-Print Network [OSTI]

    Ángel Rivas; Miguel A. Martin-Delgado

    2013-01-17

    We derive a master equation that allows us to study non-equilibrium dynamics of a quantum antiferromagnet. By resorting to spin-wave theory, we obtain a closed analytic form for the magnon decay rates. These turn out to be closely related to form factors, which are experimentally accessible by means of neutron and Raman scattering. Furthermore, we compute the time evolution of the staggered magnetization showing that, for moderate temperatures, the magnetic order is not spoiled even if the coupling is fully isotropic.

  13. Dynamic selective switching in antiferromagnetically-coupled bilayers close to the spin reorientation transition

    E-Print Network [OSTI]

    Fern ández-Pacheco, A.; Ummelen, F. C.; Mansell, R.; Petit, D.; Lee, J. H.; Swagten, H. J. M.; Cowburn, R. P.

    2014-09-05

    , Phys. Rev. Lett. 98, 117204, (2007). 19P. J. Metaxas, R. L. Stamps, J.-P. Jamet, J. Ferr#2;e, V. Baltz, B. Rodmacq, and P. Politi, Phys. Rev. Lett. 104, 237206 (2010). 20N. Wiese, T. Dimopoulos, M. R€uhrig, J. Wecker, and G. Reiss, J. Appl. Phys. 98... Dynamic selective switching in antiferromagnetically-coupled bilayers close to the spin reorientation transition A. Fernández-Pacheco, F. C. Ummelen, R. Mansell, D. Petit, J. H. Lee, H. J. M. Swagten, and R. P. Cowburn Citation: Applied Physics...

  14. Homogeneous versus spiral phases of hole-doped antiferromagnets: A systematic effective field theory investigation

    SciTech Connect (OSTI)

    Bruegger, C.; Kaempfer, F.; Wiese, U.-J.; Hofmann, C. P.; Pepe, M.

    2007-01-01

    Using the low-energy effective field theory for magnons and holes--the condensed matter analog of baryon chiral perturbation theory for pions and nucleons in QCD--we study different phases of doped antiferromagnets. We systematically investigate configurations of the staggered magnetization that provide a constant background field for doped holes. The most general configuration of this type is either constant itself or represents a spiral in the staggered magnetization. Depending on the values of the low-energy parameters, a homogeneous phase, a spiral phase, or an inhomogeneous phase is energetically favored. The reduction of the staggered magnetization upon doping is also investigated.

  15. Response to “Comment on ‘General rotating quantum vortex filaments in the low-temperature Svistunov model of the local induction approximation’” [Phys. Fluids 26, 119101 (2014)

    SciTech Connect (OSTI)

    Van Gorder, Robert A.

    2014-11-15

    In R. A. Van Gorder, “General rotating quantum vortex filaments in the low-temperature Svistunov model of the local induction approximation,” Phys. Fluids 26, 065105 (2014) I discussed properties of generalized vortex filaments exhibiting purely rotational motion under the low-temperature Svistunov model of the local induction approximation. Such solutions are stationary in terms of translational motion. In the Comment [N. Hietala, “Comment on ‘General rotating quantum vortex filaments in the low-temperature Svistunov model of the local induction approximation’ [Phys. Fluids 26, 065105 (2014)],” Phys. Fluids 26, 119101 (2014)], the author criticizes my paper for not including translational motion (although it was clearly stated that the filament motion was assumed rotational). As it turns out, if one is interested in studying the geometric structure of solutions (which was the point of my paper), one obtains the needed qualitative results on the structure of such solutions by studying the purely rotational case. Nevertheless, in this Response I shall discuss the vortex filaments that have both rotational and translational motions. I then briefly discuss why one might want to study such generalized rotating filament solutions, in contrast to simple the standard helical or planar examples (which are really special cases). I also discuss how one can study the time evolution of filaments which exhibit more complicated dynamics than pure translation and rotation. Doing this, one can study non-stationary solutions which initially appear purely rotational and gradually display other dynamics as the filaments evolve.

  16. Antiferromagnetic exchange in a bis(imido) uranium (V) dimeric complex

    SciTech Connect (OSTI)

    Spencer, Liam P [Los Alamos National Laboratory; Schelter, Eric J [Los Alamos National Laboratory; Boncella, James M [Los Alamos National Laboratory; Yang, Ping [Los Alamos National Laboratory; Gdula, Robyn L [NON LANL; Scott, Brian L [Los Alamos National Laboratory; Thompson, Joe D [Los Alamos National Laboratory; Kiplinger, Jacqueline L [Los Alamos National Laboratory; Batista, Enrique R [Los Alamos National Laboratory

    2008-01-01

    Magnetic coupling between two or more metal centers is an important facet of d- and f-block transition metal chemistry due to its implications in chemical bonding. With respect to actinide metals, magnetic coupling between polymetallic actinide centers is less well-known. Of the few documented examples, only one bimetallic uranium(V) complex, [(MeC{sub 5}H{sub 4}){sub 2}U]{sub 2}[{mu}-1,4-N{sub 2}C{sub 6}H{sub 4}] (1), has unequivocally demonstrated antiferromagnetic coupling. This complex employs a {pi}-conjugated 1,4-phenylenedimide ligand system which bridges the two f{sup 1}-metal centers and enables antiferromagentic coupling between unpaired f-e1ectrons residing in a {pi}-symmetry orbital. In this communication, we report the synthesis of a dimeric bis(imido) uranium(V) iodide complex and demonstrate with magnetic susceptibility measurements and density functional theory (DFT) calculations that the f{sup 1}-uranium centers display antiferromagnetic coupling at low temperatures.

  17. Remarkably robust and correlated coherence and antiferromagnetism in (Ce1-x Lax)Cu?Ge?

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Hodovanets, H.; Bud’ko, S.? L.; Straszheim, W.? E.; Taufour, V.; Mun, E.? D.; Kim, H.; Flint, R.; Canfield, P.? C.

    2015-06-08

    We present magnetic susceptibility, resistivity, specific heat, and thermoelectric power measurements on (Ce1-x Lax)Cu?Ge? single crystals (0 ? x ? 1). With La substitution, the antiferromagnetic temperature TN is suppressed in an almost linear fashion and moves below 0.36 K, the base temperature of our measurements for x > 0.8. Surprisingly, in addition to robust antiferromagnetism, the system also shows low temperature coherent scattering below Tcoh up to ~ 0.9 of La, indicating a small percolation limit ~ 9% of Ce. Tcoh as a function of magnetic field was found to have different behavior for x more »> 0.9. Remarkably, (Tcoh)² at H = 0 was found to be linearly proportional to TN. The jump in the magnetic specific heat ?Cm at TN as a function of TK/TN for (Ce1-x Lax)Cu?Ge? follows the theoretical prediction based on the molecular field calculation for the S = 1/2 resonant level model.« less

  18. Pressurized water nuclear reactor system with hot leg vortex mitigator

    DOE Patents [OSTI]

    Lau, Louis K. S. (Monroeville, PA)

    1990-01-01

    A pressurized water nuclear reactor system includes a vortex mitigator in the form of a cylindrical conduit between the hot leg conduit and a first section of residual heat removal conduit, which conduit leads to a pump and a second section of residual heat removal conduit leading back to the reactor pressure vessel. The cylindrical conduit is of such a size that where the hot leg has an inner diameter D.sub.1, the first section has an inner diameter D.sub.2, and the cylindrical conduit or step nozzle has a length L and an inner diameter of D.sub.3 ; D.sub.3 /D.sub.1 is at least 0.55, D.sub.2 is at least 1.9, and L/D.sub.3 is at least 1.44, whereby cavitation of the pump by a vortex formed in the hot leg is prevented.

  19. Magneto-Vortex Dynamo Model in Solar convection zone

    E-Print Network [OSTI]

    Sergey V. Ershkov

    2011-01-06

    Here is presented a new magneto-vortex dynamo model for modeling & predicting of a processes in Solar plasma convection zone. Solar convection zone is located above the level r > 0,6-0,7 R, where R is a Solar radius. A key feature of such a model is that equation of Solar plasma motion as well as equation of magnetic fields evolution - are reduced to Helmholtz's vortex equation, which is up-graded in according with alpha-effect (Coriolis force forms an additional vorticity field or magnetic field due to Sun's differential rotation). Such an additional vorticity or magnetic field are proved to be concentrated at the proper belt in Solar convection zone under the influence of Coriolis force (at the middle latitudes of the Sun in respect to equator). Besides, such an an additional vorticity & magnetic fields are to be the basic sources of well-known phenomena "Maunder's butterfly" diagram.

  20. Super Stability of Laminar Vortex Flow in Superfluid 3He-B

    E-Print Network [OSTI]

    V. B. Eltsov; R. de Graaf; P. J. Heikkinen; J. J. Hosio; R. Hanninen; M. Krusius; V. S. L'vov

    2010-05-04

    Vortex flow remains laminar up to large Reynolds numbers (Re~1000) in a cylinder filled with 3He-B. This is inferred from NMR measurements and numerical vortex filament calculations where we study the spin up and spin down responses of the superfluid component, after a sudden change in rotation velocity. In normal fluids and in superfluid 4He these responses are turbulent. In 3He-B the vortex core radius is much larger which reduces both surface pinning and vortex reconnections, the phenomena, which enhance vortex bending and the creation of turbulent tangles. Thus the origin for the greater stability of vortex flow in 3He-B is a quantum phenomenon. Only large flow perturbations are found to make the responses turbulent, such as the walls of a cubic container or the presence of invasive measuring probes inside the container.

  1. Highly efficient electron vortex beams generated by nanofabricated phase holograms

    SciTech Connect (OSTI)

    Grillo, Vincenzo; Mafakheri, Erfan; Frabboni, Stefano

    2014-01-27

    We propose an improved type of holographic-plate suitable for the shaping of electron beams. The plate is fabricated by a focused ion beam on a silicon nitride membrane and introduces a controllable phase shift to the electron wavefunction. We adopted the optimal blazed-profile design for the phase hologram, which results in the generation of highly efficient (25%) electron vortex beams. This approach paves the route towards applications in nano-scale imaging and materials science.

  2. Vortex energy and 360 Neel walls in thinfilm

    E-Print Network [OSTI]

    .Ignat@math.u-psud.fr) Courant Institute, New York University, New York, NY 10012, USA (e-mail: knuepfer@cims.nyu.edu) 1 #12Vortex energy and 360 ­N´eel walls in thin­film micromagnetics Radu Ignat , Hans Kn¨upfer October-section. The model is based on the following energy functional: E2d (m) = Z B2 |m|2 dx + | ln | 2 Z R2 ||-1

  3. Vortex energy and 360 Neel wall in thinfilm

    E-Print Network [OSTI]

    Ignat, Radu

    .Ignat@math.u-psud.fr) Courant Institute, New York University, New York, NY 10012, USA (e-mail: knuepfer@cims.nyu.edu) 1 #12Vortex energy and 360 ­N´eel wall in thin­film micromagnetics Radu Ignat , Hans Kn¨upfer October-section. The model is based on the following energy functional: E2d (m) = Z B2 |m|2 dx + | ln | 2 Z R2 ||-1

  4. X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    alloy) revealed a way to easily switch the vortex polarization with a small alternating electrical current, but how the switching actually occurred has remained speculative in...

  5. Equilibrium vortex motion in two- and three-dimensional suprconductors studied with a dc SQUID

    E-Print Network [OSTI]

    Shaw, Timothy J.

    2010-01-01

    is determined by thermal activation between pinning sites.is determined by thermal activation, it is important tothe SQUID washer. Thermal activation of the vortex between

  6. Hummingbirds generate bilateral vortex loops during hovering: evidence from flow visualization

    E-Print Network [OSTI]

    Pournazeri, Sam; Segre, Paolo; Princevac, Marko; Altshuler, Douglas

    2012-01-01

    energetic cost of flight (Rayner and Gordon 1998; Hedenstro¨generates one vortex ring per stroke (Rayner 1979; Ellington1984; Pennycuick 1988; Rayner and Gordon 1998), which would

  7. Coordinate Bethe ansatz computation for low temperature behavior of a triangular lattice of a spin-1 Heisenberg antiferromagnet

    SciTech Connect (OSTI)

    Shuaibu, A. [Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia and Physics Department, Faculty of Science, Nigerian Defence Academy, P.M.B 2109, Kaduna (Nigeria); Rahman, M. M. [Physics Department, Faculty of Science, Nigerian Defence Academy, P.M.B 2109, Kaduna (Nigeria)

    2014-03-05

    We study the low temperature behavior of a triangular lattice quantum spin-1 Heisenberg antiferromagnet with single-site anisotropy by using coordinate Bethe ansatz method. We compute the standard two-particle Hermitian Hamiltonian, and obtain the eigenfunctions and eigenvalue of the system. The obtained results show a number of advantages in comparison with many results.

  8. Scanning tunneling microscopy reveals LiMnAs is a room temperature anti-ferromagnetic semiconductor

    SciTech Connect (OSTI)

    Wijnheijmer, A. P.; Koenraad, P. M.; Marti, X.; Holy, V.; Cukr, M.; Novak, V.; Jungwirth, T.

    2012-03-12

    We performed scanning tunneling microscopy and spectroscopy on a LiMnAs(001) thin film epitaxially grown on an InAs(001) substrate by molecular beam epitaxy. While the in situ cleavage exposed only the InAs(110) non-polar planes, the cleavage continued into the LiMnAs thin layer across several facets. We combined both topography and current mappings to confirm that the facets correspond to LiMnAs. By spectroscopy we show that LiMnAs has a band gap. The band gap evidenced in this study, combined with the known Neel temperature well above room temperature, confirms that LiMnAs is a promising candidate for exploring the concepts of high temperature semiconductor spintronics based on antiferromagnets.

  9. Conductance of ferro- and antiferro-magnetic single-atom contacts: A first-principles study

    SciTech Connect (OSTI)

    Tan, Zhi-Yun [School of Physics and Mechanical and Electrical Engineering, Zunyi Normal College, Zunyi (China)] [School of Physics and Mechanical and Electrical Engineering, Zunyi Normal College, Zunyi (China); Zheng, Xiao-long; Ye, Xiang; Xie, Yi-qun [Department of Physics, Shanghai Normal University, 100 Guilin Road, Shanghai 200232 (China)] [Department of Physics, Shanghai Normal University, 100 Guilin Road, Shanghai 200232 (China); Ke, San-Huang [Department of Physics, Key Laboratory of Advanced Microstructured Materials, MOE, Tongji University, 1239 Siping Road, Shanghai 200092 (China)] [Department of Physics, Key Laboratory of Advanced Microstructured Materials, MOE, Tongji University, 1239 Siping Road, Shanghai 200092 (China)

    2013-08-14

    We present a first-principles study on the spin dependent conductance of five single-atom magnetic junctions consisting of a magnetic tip and an adatom adsorbed on a magnetic surface, i.e., the Co-Co/Co(001) and Ni-X/Ni(001) (X = Fe, Co, Ni, Cu) junctions. When their spin configuration changes from ferromagnetism to anti-ferromagnetism, the spin-up conductance increases while the spin-down one decreases. For the junctions with a magnetic adatom, there is nearly no spin valve effect as the decreased spin-down conductance counteracts the increased spin-up one. For the junction with a nonmagnetic adatom (Ni-Cu/Ni(001)), a spin valve effect is obtained with a variation of 22% in the total conductance. In addition, the change in spin configuration enhances the spin filter effect for the Ni-Fe/Ni(001) junction but suppresses it for the other junctions.

  10. Dispersive magnetic excitations in the S=1 antiferromagnet Ba3Mn2O8

    SciTech Connect (OSTI)

    Stone, Matthew B [ORNL; Lumsden, Mark D [ORNL; Qiu, Y. [National Institute of Standards and Technology (NIST); Samulon, Eric C [Stanford University; Batista, C. D. [Los Alamos National Laboratory (LANL); Fisher, Ian R [Stanford University

    2008-01-01

    We present powder inelastic neutron scattering measurements of the $S=1$ dimerized antiferromagnet Ba$_3$Mn$_2$O$_8$. The $T=1.4$~K~magnetic spectrum exhibits a spin-gap of $\\Delta = 0.9$~meV and a dispersive spectrum with a bandwidth of approximately $1.74$~meV. Comparison to coupled dimer models describe the dispersion and scattering intensity accurately and determine the exchange constants in Ba$_3$Mn$_2$O$_8$. Interdimer exchange between triangular lattice dimer bilayers in Ba$_3$Mn$_2$O$_8$ is two orders of magnitude weaker than intradimer exchange. Ba$_3$Mn$_2$O$_8$ is thus a quasi-two-dimensional frustrated bilayer triangular lattice of $S=1$ dimers. The wave vector dependent scattering intensity confirms the proposed $S=1$ dimer bond. Temperature dependent measurements of the magnetic excitations indicate the presence of both singlet-triplet and thermally activated triplet-quintet excitations.

  11. Antiferromagnetic resonance excitation by terahertz magnetic field resonantly enhanced with split ring resonator

    SciTech Connect (OSTI)

    Mukai, Y. [Department of Physics, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan); Hirori, H., E-mail: hirori@icems.kyoto-u.ac.jp [Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Sakyo-ku, Kyoto 606-8501 (Japan); CREST, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012 (Japan); Yamamoto, T. [Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510 (Japan); Kageyama, H. [Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Sakyo-ku, Kyoto 606-8501 (Japan); Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510 (Japan); Tanaka, K., E-mail: kochan@scphys.kyoto-u.ac.jp [Department of Physics, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan); Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Sakyo-ku, Kyoto 606-8501 (Japan); CREST, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012 (Japan)

    2014-07-14

    Excitation of antiferromagnetic resonance (AFMR) in a HoFeO{sub 3} crystal combined with a split ring resonator (SRR) is studied using terahertz (THz) electromagnetic pulses. The magnetic field in the vicinity of the SRR is induced by the incident THz electric field component and excites spin oscillations that correspond to the AFMR, which are directly probed by the Faraday rotation of the polarization of a near-infrared probe pulse. The good agreement of the temperature-dependent magnetization dynamics with the calculation using the two-lattice Landau-Lifshitz-Gilbert equation confirms that the AFMR is excited by the THz magnetic field, which is enhanced at the SRR resonance frequency by a factor of 20 compared to the incident magnetic field.

  12. Light-control of the ultrafast demagnetization pathway in an antiferromagnetic insulator

    E-Print Network [OSTI]

    Sala, Vera G; Miller, Timothy A; Viola, Daniele; Luppi, Elenora; Véniard, Valérie; Cerullo, Giulio; Wall, Simon

    2015-01-01

    Ultrafast demagnetization is a complex process involving strong coupling between electronic, spin, and structural degrees of freedom which is dependent on the type of magnetic order and band structure. Controlling these interactions is key for developing magnetic devices that can fully exploit femto-magnetism. Here we show that energy and polarization tunable femtosecond light pulses can be used to control the demagnetization pathway in the antiferromagnetic insulator Cr2O3. We visualize how the demagnetization dynamics depends on the pump photon energy using transient second harmonic spectroscopy. This enables us to monitor changes to the magnetic and crystalline symmetry, revealing the key role played by phonons in the demagnetization process. The phonon symmetry can be selected through the colour and polarization of the pump pulse, providing control over the demagnetization process, which could lead to faster and more efficient control of magnetic order.

  13. Spin reorientation and Ce-Mn coupling in antiferromagnetic oxypnictide CeMnAsO

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhang, Qiang; Tian, Wei; Peterson, Spencer G.; Dennis, Kevin W.; Vaknin, David

    2015-02-18

    Structure and magnetic properties of high-quality polycrystlline CeMnAsO, a parent compound of the “1111”-type oxypnictides, have been investigated using neutron powder diffraction and magnetization measurements. We find that CeMnAsO undergoes a C-type antiferromagnetic order with Mn2+(S = 5/2) moments pointing along the c axis below a relatively high Néel temperature of TN = 347(1) K. Below TSR = 35 K, two simultaneous transitions occur where the Mn moments reorient from the c axis to the ab plane preserving the C-type magnetic order, and Ce moments undergo long-range AFM ordering with antiparallel moments pointing in the ab plane. Another transition tomore »a noncollinear magnetic structure occurs below 7 K. The ordered moments of Mn and Ce at 2 K are 3.32(4) ?B and 0.81(4)?B, respectively. We find that CeMnAsO primarily falls into the category of a local-moment antiferromagnetic insulator in which the nearest-neighbor interaction (J1) is dominant with J2 1/2 in the context of J1 – J2 – Jc model. The spin reorientation transition driven by the coupling between Ce and the transition metal seems to be common to Mn, Fe, and Cr ions, but not to Co and Ni ions in the isostructural oxypnictides. As a result, a schematic illustration of magnetic structures in Mn and Ce sublattices in CeMnAsO is presented.« less

  14. Vortex-induced vibration of a circular cylinder with combined in-line and cross-flow motion

    E-Print Network [OSTI]

    Dahl, Jason (Jason Michael)

    2008-01-01

    Deep water, string-like, marine risers subject to strong ocean currents, suffer from vortex-induced vibrations (VIV), where vortex shedding interacts with the structural properties of the riser, resulting in large amplitude ...

  15. The role of vortex wake dynamics in the flow-induced vibration of tube arrays

    E-Print Network [OSTI]

    Kevlahan, Nicholas

    The role of vortex wake dynamics in the flow-induced vibration of tube arrays N.K.-R. Kevlahan Keywords: Fluid­structure interaction Vortex-induced vibration Tube arrays Potential flow a b s t r a c in the non-resonant flow-induced vibration of periodic tube arrays. This dual approach untangles the effects

  16. Determination of magnetic vortex chirality using lateral spin-valve and Y. Otani

    E-Print Network [OSTI]

    Otani, Yoshichika

    Determination of magnetic vortex chirality using lateral spin-valve geometry T. Kimuraa and Y October 2005 We demonstrate the determination of the vortex chirality using a nonlocal spin-valve measurement technique in a lateral spin valve consisting of a Permalloy Py disk 1 m in diameter and a Py wire

  17. Laminar Flow of a Sheared Vortex Crystal: Scars in Flat Geometry M.-Carmen Miguel,1

    E-Print Network [OSTI]

    Miguel-Lopez, Carmen

    Laminar Flow of a Sheared Vortex Crystal: Scars in Flat Geometry M.-Carmen Miguel,1 Adil Mughal,2 November 2010; published 15 June 2011) We consider the laminar flow of a vortex crystal in the Corbino disk geometry. Laminar flow can be induced by thermal fluctuations melting the crystal, but also by shear stress

  18. Resuspension onset and crater erosion by a vortex ring interacting with a particle layer

    E-Print Network [OSTI]

    Dalziel, Stuart

    Resuspension onset and crater erosion by a vortex ring interacting with a particle layer N. Bethke. Fluids 24, 055106 (2012) Conveyor belt effect in the flow through a tube of a viscous fluid with spinning and crater erosion by a vortex ring interacting with a particle layer N. Bethkea) and S. B. Dalziel

  19. Impact of vortex core structure on equftion of motion V.A.Budarin

    E-Print Network [OSTI]

    1 Impact of vortex core structure on equftion of motion V.A.Budarin National Polytechnical-solid hollow and continuous vortex core wall has been examined in this paper. Two other exact solutions derived of thick-walled cylinders and task about the tube rotation. Comparison of the results obtained has been

  20. Mixing characteristics of compressible vortex rings interacting with normal shock waves

    SciTech Connect (OSTI)

    Cetegen, B.M. . Mechanical Engineering Dept.); Hermanson, J.C. )

    1995-01-01

    Current interest in the interaction between compressible vortical flows and shock waves is largely motivated by the need to promote rapid, loss-effective mixing and combustion of hydrogen and hydrocarbon fuels for supersonic combustor applications. The instability mechanisms and mixing enhancement arising from the interaction of a compressible vortex ring with a normal shock wave were studied in a colinear, dual-shock tube. This flow geometry simulates features of the interaction of a shock wave with a jet containing streamwise vorticity, a configuration of significant interest for supersonic combustion applications. Flow visualization and quantitative concentration measurements were performed by planar laser Rayleigh scattering. For a given primary shock strength, interfacial instability is more evident in a weak vortex ring than in a strong vortex ring. In all cases, the identity of the vortex ring is lost after a sufficiently long time of interaction. The probability density function of the mixed fluid changes rapidly from a bimodal distribution to a single peak upon processing by a shock wave. The most probable concentration decreases with time, indicating a rapid increase in mixing and dilution of the vortex fluid. The mixing enhancement is most rapid for the case of a strong vortex ring interacting with a strong shock wave, somewhat slower for a weak vortex ring and a strong shock wave, and significantly slower for the case of a strong vortex ring and a weaker shock wave. These observations are consistent with the earlier numerical predictions.

  1. Comparison of optical vortex detection methods for use with a Shack-Hartmann

    E-Print Network [OSTI]

    Dainty, Chris

    Comparison of optical vortex detection methods for use with a Shack-Hartmann wavefront sensor Kevin of de- tecting optical vortices from Shack-Hartmann wavefront sensor (SHWFS) data, the vortex potential of Shack-Hartmann wavefront sensing," J. Refract. Surg. 17, S573­S577 (2001). 13. J. Notaras and C

  2. A Model of Compressor Blade Row Interaction with Shock Induced Vortex Shedding

    E-Print Network [OSTI]

    Cincinnati, University of

    A Model of Compressor Blade Row Interaction with Shock Induced Vortex Shedding Mark G. Turner". The mid and far spacings represent typical axial gaps found in operational fans and compressors. However behind a stator are modeled. The model is based on a Burger vortex core model for shed vortices

  3. Numerical Simulation of Vortex Pyrolysis Reactors for Condensable Tar Production from Biomass

    E-Print Network [OSTI]

    Miller, Richard S.

    Numerical Simulation of Vortex Pyrolysis Reactors for Condensable Tar Production from Biomass R. S is performed in order to evaluate the performance and optimal operating conditions of vortex pyrolysis reactors particle pyrolysis is coupled with a compressible Reynolds stress transport model for the turbulent reactor

  4. Nanogenerator as an active sensor for vortex capture and ambient wind-velocity detection

    E-Print Network [OSTI]

    Wang, Zhong L.

    efficiently convert the vortex motion in the atmosphere into electricity. Based on the Karman vortex street in wireless environmental monitoring networks. 1. Introduction Self-powered nanosystem is a promising concept for the realization of environmental wireless sensor networks. Due to the enormous demands of distributed nodes

  5. The critical velocity for vortex existence in a two dimensional rotating Bose-Einstein condensate

    E-Print Network [OSTI]

    Ignat, Radu

    The critical velocity for vortex existence in a two dimensional rotating Bose-Einstein condensate-Einstein condensate. It consists in minimizing a Gross-Pitaevskii functional defined in R2 under the unit mass constraint. We estimate the critical rotational speed 1 for vortex existence in the bulk of the condensate

  6. Generalized London free energy for high-Tc vortex lattices Ian Affleck

    E-Print Network [OSTI]

    Franz, Marcel

    Generalized London free energy for high-Tc vortex lattices Ian Affleck Department of Physics-1829 97 50402-4 The London free energy provides a very simple way of studying the vortex lattice that this effect can arise from additional quartic derivative terms in the Ginzburg-Landau GL free energy4­7 or

  7. A model for universal time scale of vortex ring formation Kamran Mohseni

    E-Print Network [OSTI]

    Mohseni, Kamran

    and Applied Science, 104-44, California Institute of Technology, Pasadena, California 91125 Morteza Gharib Graduate Aeronautical Laboratory, California Institute of Technology, Pasadena, California 91125 Received of the fluid out of the cylinder and the approximation of the vortex at the pinch off moment by a vortex

  8. Modeling bubble-vortex interactions Modeling and simulation of multiple bubble entrainment and interactions with two

    E-Print Network [OSTI]

    Apte, Sourabh V.

    Modeling bubble-vortex interactions Modeling and simulation of multiple bubble entrainment entrainment and interactions with two dimensional vorti- cal flows are preformed using a Discrete Element microbubbles entrained in a traveling vortex tube is studied in detail. The test case resembles the experiments

  9. Slowing of vortex rings by development of Kelvin waves Robert E. Hershberger, Diogo Bolster, and Russell J. Donnelly*

    E-Print Network [OSTI]

    Bolster, Diogo

    , at least for a straight vortex tube case, results from subjection to a straining field in a planeSlowing of vortex rings by development of Kelvin waves Robert E. Hershberger, Diogo Bolster the slowing of viscous vortex rings. In particular we do so using the concept of drag coefficient, which

  10. American Institute of Aeronautics and Astronautics An Experimental Study of the Stability of a Four-Vortex

    E-Print Network [OSTI]

    Nelson, Robert C.

    . Helium bubbles were introduced into the core region of individual vortices to visualize these wake. These results suggest that the use of helium bubbles is a suitable method for visualizing wake vortices programs can be divided into two categories, vortex detection and vortex alleviation. The vortex detection

  11. Glass-like recovery of antiferromagnetic spin ordering in a photo-excited manganite Pr0.7Ca0.3MnO3

    SciTech Connect (OSTI)

    Zhou, S.Y.; Langner, M.C.; Zhu, Y.; Chuang, Y.-D.; Rini, M.; Glover, T.E.; Hertlein, M.P.; Gonzalez, A.G. Cruz; Tahir, N.; Tomioka, Y.; Tokura, Y.; Hussain, Z.; Schoenlein, R.W.

    2014-01-16

    Electronic orderings of charges, orbitals and spins are observed in many strongly correlated electron materials, and revealing their dynamics is a critical step toward understanding the underlying physics of important emergent phenomena. Here we use time-resolved resonant soft x-ray scattering spectroscopy to probe the dynamics of antiferromagnetic spin ordering in the manganite Pr0:7Ca0:3MnO3 following ultrafast photo-exitation. Our studies reveal a glass-like recovery of the spin ordering and a crossover in the dimensionality of the restoring interaction from quasi-1D at low pump fluence to 3D at high pump fluence. This behavior arises from the metastable state created by photo-excitation, a state characterized by spin disordered metallic droplets within the larger charge- and spin-ordered insulating domains. Comparison with time-resolved resistivity measurements suggests that the collapse of spin ordering is correlated with the insulator-to-metal transition, but the recovery of the insulating phase does not depend on the re-establishment of the spin ordering.

  12. New insulating antiferromagnetic quaternary iridates MLa10Ir4O24 (M=Sr, Ba)

    SciTech Connect (OSTI)

    Zhao, Qingbiao; Han, Fei; Stoumpos, Constantinos C.; Han, Tian -Heng; Li, Hao; Mitchell, J. F.

    2015-07-01

    Recently, oxides of Ir4+ have received renewed attention in the condensed matter physics community, as it has been reported that certain iridates have a strongly spin-orbital coupled (SOC) electronic state, Jeff = ½, that defines the electronic and magnetic properties. The canonical example is the Ruddlesden-Popper compound Sr2IrO4, which has been suggested as a potential route to a new class of high temperature superconductor due to the formal analogy between Jeff = ½ and the S = ½ state of the cuprate superconductors. The quest for other iridium oxides that present tests of the underlying SOC physics is underway. In this spirit, here we report the synthesis and physical properties of two new quaternary tetravalent iridates, MLa10Ir4O24 (M = Sr, Ba). The crystal structure of both compounds features isolated IrO6 octahedra in which the electronic configuration of Ir is d5. As a result, both compounds order antiferromagnetically despite the lack of obvious superexchange pathways, and resistivity measurement shows that SrLa10Ir4O24 is an insulator.

  13. Gradient catastrophe and flutter in vortex filament dynamics

    E-Print Network [OSTI]

    B. G. Konopelchenko; G. Ortenzi

    2011-06-02

    Gradient catastrophe and flutter instability in the motion of vortex filament within the localized induction approximation are analyzed. It is shown that the origin if this phenomenon is in the gradient catastrophe for the dispersionless Da Rios system which describes motion of filament with slow varying curvature and torsion. Geometrically this catastrophe manifests as a rapid oscillation of a filament curve in a point that resembles the flutter of airfoils. Analytically it is the elliptic umbilic singularity in the terminology of the catastrophe theory. It is demonstrated that its double scaling regularization is governed by the Painlev\\'e-I equation.

  14. Magnetic Vortex Core Reversal by Low-Field Excitations

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would likeUniverseIMPACTThousandReport) |Administration SavannahMagnetic Vortex Core

  15. Magnetic Vortex Core Reversal by Low-Field Excitations

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would likeUniverseIMPACTThousandReport) |Administration SavannahMagnetic Vortex CoreMagnetic

  16. Magnetic Vortex Core Reversal by Low-Field Excitations

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would likeUniverseIMPACTThousandReport) |Administration SavannahMagnetic Vortex

  17. Magnetic Vortex Core Reversal by Low-Field Excitations

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would likeUniverseIMPACTThousandReport) |Administration SavannahMagnetic VortexMagnetic

  18. Magnetic Vortex Core Reversal by Low-Field Excitations

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would likeUniverseIMPACTThousandReport) |Administration SavannahMagneticMagnetic Vortex Core

  19. Vortex nozzle for segmenting and transporting metal chips from turning operations

    DOE Patents [OSTI]

    Bieg, L.F.

    1993-04-20

    Apparatus for collecting, segmenting and conveying metal chips from machining operations utilizes a compressed gas driven vortex nozzle for receiving the chip and twisting it to cause the chip to segment through the application of torsional forces to the chip. The vortex nozzle is open ended and generally tubular in shape with a converging inlet end, a constant diameter throat section and a diverging exhaust end. Compressed gas is discharged through angled vortex ports in the nozzle throat section to create vortex flow in the nozzle and through an annular inlet at the entrance to the converging inlet end to create suction at the nozzle inlet and cause ambient air to enter the nozzle. The vortex flow in the nozzle causes the metal chip to segment and the segments thus formed to pass out of the discharge end of the nozzle where they are collected, cleaned and compacted as needed.

  20. Structural investigations on Co{sub 3-x}Mn{sub x}TeO{sub 6}; (0 < x ? 2); High temperature ferromagnetism and enhanced low temperature anti-ferromagnetism

    SciTech Connect (OSTI)

    Singh, Harishchandra; Sinha, A. K. E-mail: hng@rrcat.gov.in; Ghosh, Haranath E-mail: hng@rrcat.gov.in; Singh, M. N.; Rajput, Parasmani; Prajapat, C. L.; Singh, M. R.; Ravikumar, G.

    2014-08-21

    In the quest of materials with high temperature ferromagnetism and low temperature anti-ferromagnetism, we prepare Co{sub 3-x}Mn{sub x}TeO{sub 6}; (0?state, Co{sup 2+}/Mn{sup 2+} and Co{sup 3+}/Mn{sup 3+}. Relative ratios of Co{sup 3+}/Co{sup 2+} and Mn{sup 3+}/Mn{sup 2+} obtained using Linear combination fit decrease with increasing x (for x???0.5). These structural and spectroscopic evidences are used to provide possible interpretation of the observed paramagnetic to ferromagnetic transition at around 185?K followed by an enhanced antiferromagnetic transition ?45?K for x?=?0.5.

  1. The Relation Between Dry Vortex Merger and Tropical Cyclone Genesis over the Atlantic Ocean

    SciTech Connect (OSTI)

    Chen, Shu-Hua; Liu, Yi-Chin

    2014-10-27

    A strong, convective African tropical disturbance has a greater chance to develop into a Tropical 23 Depression (TD) if it merges with a shallow, dry vortex (D-vortex) from the north of the African 24 easterly jet (AEJ) after leaving the western coast. Using 11-year reanalysis data we found that the 25 western tip of a vortex strip at northwestern Africa can serve as dry vortices for the D-vortex 26 merger if it shifts southward. Another source of D-vortices is the westward propagating lows 27 along the southern edge of the Saharan air. The D-vortex merger process occurred for 63.5% of 28 tropical cyclones (TCs) or developing systems over the main development region of the Atlantic 29 Ocean, while it occurred for 54% of non-developing systems. TC genesis could be largely 30 controlled by the large-scale environment, but the differences in characteristics of vortices 31 associated with the D-vortex merger between developing and non-developing systems could 32 potentially help determine their destinies; in general, developing systems were dominated by a 33 more intense and moist south vortex, while non-developing systems were dominated by a north 34 vortex which was more intense, drier, and larger in size. Analysis also shows that 74% of intense 35 developing systems were involved with the D-vortex merger process. More attention needs to be 36 paid to the D-vortex merger and the characteristics of those vortices as they can play significant 37 roles or have a strong indication in Atlantic TC genesis.

  2. Antiferromagnetism in EuCu2As2 and EuCu1.82Sb2 single crystals

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Anand, V. K.; Johnston, D. C.

    2015-05-07

    Single crystals of EuCu2As2 and EuCu2Sb2 were grown from CuAs and CuSb self-flux, respectively. The crystallographic, magnetic, thermal, and electronic transport properties of the single crystals were investigated by room-temperature x-ray diffraction (XRD), magnetic susceptibility ? versus temperature T, isothermal magnetization M versus magnetic field H, specific heat Cp(T), and electrical resistivity ?(T) measurements. EuCu2As2 crystallizes in the body-centered tetragonal ThCr2Si2-type structure (space group I4/mmm), whereas EuCu2Sb2 crystallizes in the related primitive tetragonal CaBe2Ge2-type structure (space group P4/nmm). The energy-dispersive x-ray spectroscopy and XRD data for the EuCu2Sb2 crystals showed the presence of vacancies on the Cu sites, yielding themore »actual composition EuCu1.82Sb2. The ?(T) and Cp(T) data reveal metallic character for both EuCu2As2 and EuCu1.82Sb2. Antiferromagnetic (AFM) ordering is indicated from the ?(T),Cp(T), and ?(T) data for both EuCu2As2 (TN = 17.5 K) and EuCu1.82Sb2 (TN = 5.1 K). In EuCu1.82Sb2, the ordered-state ?(T) and M(H) data suggest either a collinear A-type AFM ordering of Eu+2 spins S = 7/2 or a planar noncollinear AFM structure, with the ordered moments oriented in the tetragonal ab plane in either case. This ordered-moment orientation for the A-type AFM is consistent with calculations with magnetic dipole interactions. As a result, the anisotropic ?(T) and isothermal M(H) data for EuCu2As2, also containing Eu+2 spins S = 7/2, strongly deviate from the predictions of molecular field theory for collinear AFM ordering and the AFM structure appears to be both noncollinear and noncoplanar.« less

  3. CaMn2Sb2: Spin waves on a frustrated antiferromagnetic honeycomb lattice

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    McNally, D. E.; Simonson, J. W.; Kistner-Morris, J. J.; Smith, G. J.; Hassinger, J. E.; DeBeer-Schmidt, L.; Kolesnikov, A. I.; Zaliznyak, I.; Aronson, M. C.

    2015-05-22

    We present inelastic neutron scattering measurements of the antiferromagnetic insulator CaMn2Sb2:, which consists of corrugated honeycomb layers of Mn. The dispersion of magnetic excitations has been measured along the H and L directions in reciprocal space, with a maximum excitation energy of ? 24 meV. These excitations are well described by spin waves in a Heisenberg model, including first and second neighbor exchange interactions, J1 and J2, in the Mn plane and also an exchange interaction between planes. The determined ratio J2/J1 ? 1/6 suggests that CaMn2Sb2: is the first example of a compound that lies very close to themore »mean field tricritical point, known for the classical Heisenberg model on the honeycomb lattice, where the N´eel phase and two different spiral phases coexist. The magnitude of the determined exchange interactions reveal a mean field ordering temperature ? 4 times larger than the reported N´eel temperature TN = 85 K, suggesting significant frustration arising from proximity to the tricritical point.« less

  4. Decay of helical Kelvin waves on a quantum vortex filament

    SciTech Connect (OSTI)

    Van Gorder, Robert A.

    2014-07-15

    We study the dynamics of helical Kelvin waves moving along a quantum vortex filament driven by a normal fluid flow. We employ the vector form of the quantum local induction approximation (LIA) due to Schwarz. For an isolated filament, this is an adequate approximation to the full Hall-Vinen-Bekarevich-Khalatnikov dynamics. The motion of such Kelvin waves is both translational (along the quantum vortex filament) and rotational (in the plane orthogonal to the reference axis). We first present an exact closed form solution for the motion of these Kelvin waves in the case of a constant amplitude helix. Such solutions exist for a critical wave number and correspond exactly to the Donnelly-Glaberson instability, so perturbations of such solutions either decay to line filaments or blow-up. This leads us to consider helical Kelvin waves which decay to line filaments. Unlike in the case of constant amplitude helical solutions, the dynamics are much more complicated for the decaying helical waves, owing to the fact that the rate of decay of the helical perturbations along the vortex filament is not constant in time. We give an analytical and numerical description of the motion of decaying helical Kelvin waves, from which we are able to ascertain the influence of the physical parameters on the decay, translational motion along the filament, and rotational motion, of these waves (all of which depend nonlinearly on time). One interesting finding is that the helical Kelvin waves do not decay uniformly. Rather, such waves decay slowly for small time scales, and more rapidly for large time scales. The rotational and translational velocity of the Kelvin waves depend strongly on this rate of decay, and we find that the speed of propagation of a helical Kelvin wave along a quantum filament is large for small time while the wave asymptotically slows as it decays. The rotational velocity of such Kelvin waves along the filament will increase over time, asymptotically reaching a finite value. These decaying Kelvin waves correspond to wave number below the critical value for the Donnelly-Glaberson instability, and hence our results on the Schwarz quantum LIA correspond exactly to what one would expect from prior work on the Donnelly-Glaberson instability.

  5. Vortex flow in the technology of radiation wave cracking (RWC)

    E-Print Network [OSTI]

    L. A. Tsoy; V. N. Kolushov; A. G. Komarov; A. N. Tsoy

    2012-09-16

    This article examines the theory of vortex flows in relation to the processes occurring in the radiation-wave cracking of crude oil, when the crude oil is sprayed into the gas stream in the form of a mist and then is fed into the reactor, where it is treated by the accelerated electrons and the UHF radiation. The output of this process are the products with the specified parameters (high-octane petroleum products). This process operates at the ambient pressure and temperature, which makes the process safer for industrial purposes. Besides the process itself, the authors described the equipment used in this process, as well as the parameters of the optimal process.

  6. Gas turbine engine combustor can with trapped vortex cavity

    DOE Patents [OSTI]

    Burrus, David Louis; Joshi, Narendra Digamber; Haynes, Joel Meier; Feitelberg, Alan S.

    2005-10-04

    A gas turbine engine combustor can downstream of a pre-mixer has a pre-mixer flowpath therein and circumferentially spaced apart swirling vanes disposed across the pre-mixer flowpath. A primary fuel injector is positioned for injecting fuel into the pre-mixer flowpath. A combustion chamber surrounded by an annular combustor liner disposed in supply flow communication with the pre-mixer. An annular trapped dual vortex cavity located at an upstream end of the combustor liner is defined between an annular aft wall, an annular forward wall, and a circular radially outer wall formed therebetween. A cavity opening at a radially inner end of the cavity is spaced apart from the radially outer wall. Air injection first holes are disposed through the forward wall and air injection second holes are disposed through the aft wall. Fuel injection holes are disposed through at least one of the forward and aft walls.

  7. Vortex Induced Vibrations of cylinders : experiments in reducing drag force and amplitude of motion

    E-Print Network [OSTI]

    Farrell, David Emmanuel

    2007-01-01

    Reducing the deleterious effect of Vortex Induced Vibrations (VIV) in marine risers is an important task for ocean engineers; and many competing factors exist in the design of VIV suppression devices. This thesis explores ...

  8. Numerically-based ducted propeller design using vortex lattice lifting line theory

    E-Print Network [OSTI]

    Stubblefield, John M

    2008-01-01

    This thesis used vortex lattice lifting line theory to model an axisymmetrical-ducted propeller with no gap between the duct and the propeller. The theory required to model the duct and its interaction with the propeller ...

  9. Effects of trailing edge flap dynamic deployment on blade-vortex interactions 

    E-Print Network [OSTI]

    Nelson, Carter T.

    1997-01-01

    A theoretical and experimental investigation is undertaken to determine the effects of an actively deployable trailing edge flap on the disturbances created during blade-vortex interactions (BVI). The theoretical model consists of an unsteady panel...

  10. An adaptive mesh method for the simulation of Blade Vortex Interaction 

    E-Print Network [OSTI]

    Kim, Kyu-Sup

    1998-01-01

    An adaptive mesh method for the simulation of parallel ics. Blade Vortex Interaction (BV1) with an active Trailing Edge Flap (TEF) is presented. The two-dimensional 1111-steady problem is solved by a higher order upwind Euler method...

  11. Variability of the polar stratospheric vortex and its impact on surface climate patterns

    E-Print Network [OSTI]

    Sheshadri, Aditi

    2015-01-01

    This thesis investigates various aspects of the variability of the stratospheric polar vortex and the effect of this variability on tropospheric weather and climate patterns on various timescales. In the first part of this ...

  12. Reduced gravity rankine cycle design and optimization with passive vortex phase separation 

    E-Print Network [OSTI]

    Supak, Kevin Robert

    2009-05-15

    turbo machinery, require kilowatts of power and are untested for high vapor flow conditions. The Interphase Transport Phenomena (ITP) laboratory has developed a low-power, passive microgravity vortex phase separator (MVS) which has already proven...

  13. Effect of traveling waves on Vortex-Induced Vibration of long flexible cylinders

    E-Print Network [OSTI]

    Jaiswal, Vivek, Ph. D. Massachusetts Institute of Technology

    2009-01-01

    Offshore marine risers and pipelines, exposed to ocean currents, are susceptible to Vortex-Induced Vibration (VIV). Accurate prediction of VIV is necessary for estimating the fatigue life as well as for taking corrective ...

  14. Vortex-induced vibration of flexible cylinders in time-varying flows

    E-Print Network [OSTI]

    Resvanis, Themistocles L

    2014-01-01

    This thesis investigates two aspects of Vortex-Induced Vibrations (VIV) on long flexible cylinders. The work is split into a minor and major part. The minor part addresses the effect of Reynolds number on flexible cylinder ...

  15. Enhancement of vortex induced forces and motion through surface roughness control

    DOE Patents [OSTI]

    Bernitsas, Michael M. (Saline, MI); Raghavan, Kamaldev (Houston, TX)

    2011-11-01

    Roughness is added to the surface of a bluff body in a relative motion with respect to a fluid. The amount, size, and distribution of roughness on the body surface is controlled passively or actively to modify the flow around the body and subsequently the Vortex Induced Forces and Motion (VIFM). The added roughness, when designed and implemented appropriately, affects in a predetermined way the boundary layer, the separation of the boundary layer, the level of turbulence, the wake, the drag and lift forces, and consequently the Vortex Induced Motion (VIM), and the fluid-structure interaction. The goal of surface roughness control is to increase Vortex Induced Forces and Motion. Enhancement is needed in such applications as harnessing of clean and renewable energy from ocean/river currents using the ocean energy converter VIVACE (Vortex Induced Vibration for Aquatic Clean Energy).

  16. Lagrangian analysis of fluid transport in empirical vortex ring flows Shawn C. Shadden

    E-Print Network [OSTI]

    Marsden, Jerrold

    Lagrangian analysis of fluid transport in empirical vortex ring flows Shawn C. Shadden Control and Dynamical Systems, California Institute of Technology, Pasadena, California 91125 John O. Dabiri Graduate Aeronautical Laboratories and Bioengineering, California Institute of Technology, Pasadena, California 91125

  17. Helical antiferromagnetic ordering in Lu1-xScxMnSi

    SciTech Connect (OSTI)

    Goetsch, Ryan J; Anand, V K; Johnston, David C

    2014-08-01

    Polycrystalline samples of Lu1?xScxMnSi (x=0, 0.25, 0.5) are studied using powder x-ray diffraction, heat capacity Cp, magnetization, magnetic susceptibility ?, and electrical resistivity ? measurements versus temperature T and magnetic field H. This system crystallizes in the primitive orthorhombic TiNiSi-type structure (space group Pnma) as previously reported. The ?(T) data indicate metallic behavior. The Cp(T), ?(T), and ?(T) measurements consistently indicate long-range antiferromagnetic (AF) transitions with AF ordering temperatures TN=246, 215, and 188 K for x=0, 0.25, and 0.5, respectively. A second transition is observed at somewhat lower T for each sample from the ?(T) and ?(T) measurements, which we speculate are due to spin reorientation transitions; these second transitions are completely suppressed in H=5.5 T. The Cp data below 10 K for each composition indicate an enhanced Sommerfeld electronic heat capacity coefficient for the series in the range ?=24–29 mJ/mol K2. The ?(T) measurements up to 1000 K were fitted by local-moment Curie-Weiss behaviors which indicate a low Mn spin S?1. The ? data below TN are analyzed using the Weiss molecular field theory for a planar noncollinear cycloidal AF structure with a composition-dependent pitch, following the previous neutron diffraction work of Venturini et al. [J. Alloys Compd. 256, 65 (1997)]. Within this model, the fits indicate a turn angle between Mn ordered moments along the cycloid axis of ?100? or ?145?, either of which indicate dominant AF interactions between the Mn spins in the Lu1?xScxMnSi series of compounds.

  18. Charge control of antiferromagnetism at PbZr{sub 0.52}Ti{sub 0.48}O{sub 3}/La{sub 0.67}Sr{sub 0.33}MnO{sub 3} interface

    SciTech Connect (OSTI)

    Ma, X.; Zhai, H.; Fang, F.; Lüpke, G., E-mail: gxluep@wm.edu [Department of Applied Science, College of William and Mary, 251 Jamestown Road, Williamsburg, Virginia 23187 (United States); Kumar, A. [Department of Physics and Institute for Functional Nanomaterials, University of Puerto Rico, San Juan, Puerto Rico 00931-3343 (United States); CSIR-National Physical Laboratory, New Delhi 110012 (India); Dussan, S.; Katiyar, R. S. [Department of Physics and Institute for Functional Nanomaterials, University of Puerto Rico, San Juan, Puerto Rico 00931-3343 (United States); Zhao, H. B. [Department of Optical Science and Engineering, Fudan University, 220 Handan Road, Shanghai 200433 (China); Scott, J. F. [Department of Physics and Institute for Functional Nanomaterials, University of Puerto Rico, San Juan, Puerto Rico 00931-3343 (United States); Department of Physics, Cavendish Laboratory, University of Cambridge, Cambridge CB3 OHE (United Kingdom)

    2014-03-31

    The interfacial spin state of the multiferroic heterostructure PbZr{sub 0.52}Ti{sub 0.48}O{sub 3}/La{sub 0.67}Sr{sub 0.33}MnO{sub 3} and its dependence on ferroelectric polarization is investigated with magnetic second-harmonic generation at 78?K. The spin alignment of Mn ions in the first unit cell layer at the heterointerface can be tuned from ferromagnetic to antiferromagnetic exchange coupled, while the bulk magnetization remains unchanged. Multiple domains of both phases coexist as the ferroelectric polarization is switched. The results will help promote the development of new interface-based functionalities and device concepts.

  19. Explicit mean-field radius for nearly parallel vortex filaments in statistical equilibrium

    E-Print Network [OSTI]

    Timothy D. Andersen; Chjan C. Lim

    2006-11-19

    Geophysical research has focused on flows, such as ocean currents, as two dimensional. Two dimensional point or blob vortex models have the advantage of having a Hamiltonian, whereas 3D vortex filament or tube systems do not necessarily have one, although they do have action functionals. On the other hand, certain classes of 3D vortex models called nearly parallel vortex filament models do have a Hamiltonian and are more accurate descriptions of geophysical and atmospheric flows than purely 2D models, especially at smaller scales. In these ``quasi-2D'' models we replace 2D point vortices with vortex filaments that are very straight and nearly parallel but have Brownian variations along their lengths due to local self-induction. When very straight, quasi-2D filaments are expected to have virtually the same planar density distributions as 2D models. An open problem is when quasi-2D model statistics behave differently than those of the related 2D system and how this difference is manifested. In this paper we study the nearly parallel vortex filament model of Klein, Majda, Damodaran in statistical equilibrium. We are able to obtain a free-energy functional for the system in a non-extensive thermodynamic limit that is a function of the mean square vortex position $R^2$ and solve \\emph{explicitly} for $R^2$. Such an explicit formula has never been obtained for a non-2D model. We compare the results of our formula to a 2-D formula of \\cite{Lim:2005} and show qualitatively different behavior even when we disallow vortex braiding. We further confirm our results using Path Integral Monte Carlo (Ceperley (1995)) \\emph{without} permutations and that the Klein, Majda, Damodaran model's asymptotic assumptions \\emph{are valid} for parameters where these deviations occur.

  20. Vortex in a weakly relativistic Bose gas at zero temperature and relativistic fluid approximation

    E-Print Network [OSTI]

    B. Boisseau

    2004-09-14

    The Bogoliubov procedure in quantum field theory is used to describe a relativistic almost ideal Bose gas at zero temperature. Special attention is given to the study of a vortex. The radius of the vortex in the field description is compared to that obtained in the relativistic fluid approximation. The Kelvin waves are studied and, for long wavelengths, the dispersion relation is obtained by an asymptotic matching method and compared with the non relativistic result.

  1. Investigation of Vortex Structures in Gas-Discharge Nonneutral Electron Plasma: III. Pulse Ejection of Electrons at the Formation and Radial Oscillations of Vortex Structure

    E-Print Network [OSTI]

    Kervalishvili, N A

    2015-01-01

    The results of experimental investigations of electron ejection from gas-discharge nonneutral electron plasma at the formation and radial oscillations of vortex structure have been presented. The electrons are injected from the vortex structure and the adjacent region of electron sheath in the form of pulses the duration and periodicity of which are determined by the processes of evolution and dynamics of this structure. The possible mechanisms of pulse ejection of electrons are considered. The influence of electron ejection on other processes in discharge electron sheath is analyzed.

  2. The internal structure of a vortex in a two-dimensional superfluid with long healing length and its implications

    SciTech Connect (OSTI)

    Klein, Avraham; Aleiner, Igor L.; Agam, Oded

    2014-07-15

    We analyze the motion of quantum vortices in a two-dimensional spinless superfluid within Popov’s hydrodynamic description. In the long healing length limit (where a large number of particles are inside the vortex core) the superfluid dynamics is determined by saddle points of Popov’s action, which, in particular, allows for weak solutions of the Gross–Pitaevskii equation. We solve the resulting equations of motion for a vortex moving with respect to the superfluid and find the reconstruction of the vortex core to be a non-analytic function of the force applied on the vortex. This response produces an anomalously large dipole moment of the vortex and, as a result, the spectrum associated with the vortex motion exhibits narrow resonances lying within the phonon part of the spectrum, contrary to traditional view.

  3. Dynamics of a relativistic Rankine vortex for a two-constituent superfluid in a weak perturbation of cylindrical symmetry

    E-Print Network [OSTI]

    B. Boisseau

    1999-01-18

    From a recent study of a stationary cylindrical solution for a relativistic two-constituent superfluid at low temperature limit, we propose to specify this solution under the form of a relativistic generalisation of a Rankine vortex (Potential vortex whose the core has a solid body rotation).Then we establish the dynamics of the central line of this vortex by supposing that the deviation from the cylindrical configuration is weak in the neighbourhood of the core of the vortex. In "stiff" material the Nambu-Goto equations are obtained.

  4. Specific heat of CeRhIn5: Pressure-driven evolution of the ground state from antiferromagnetism to superconductivity

    E-Print Network [OSTI]

    2001-01-01

    Specific Heat of CeRhIn5: Pressure–Driven Evolution of the32306 Measurements of the specific heat of antiferromagneticsee text). Fig. 2. (a) The specific heat, for representative

  5. Antiferromagnetic phase transition in the temperature-dependent NIR-VUV dielectric function of hexagonal YMnO$_3$

    E-Print Network [OSTI]

    Richter, Steffen; Grundmann, Marius; Schmidt-Grund, Rüdiger

    2015-01-01

    Hexagonal YMnO$_3$ is well known for the co-occurrence of ferroelectricity and antiferromagnetism at low temperatures. Using temperature-dependent spectroscopic ellipsometry at an $a$-plane oriented single crystal, we show how the dielectric function is affected by the magnetic order transition at the N\\'eel temperature. We focus especially on the pronounced charge transfer transitions around (1.6-1.7)eV which are strongly connected to Mn 3$d$ electrons. If described with a Bose-Einstein model, the temperature dependency of their energy and broadening is characterized by effective phonon energies not larger than 8meV. We argue that this is a hint for the occurrence of a soft phonon mode related to the antiferromagnetic phase transition. This is observed in both tensor components of the dielectric function, parallel and perpendicular to the crystallographic $c$-axis. Furthermore, a suitable parametrization for the uniaxial dielectric function is presented for the NIR-VUV spectral range. The broad transitions a...

  6. Vortex generation in protoplanetary disks with an embedded giant planet

    E-Print Network [OSTI]

    M. de Val-Borro; P. Artymowicz; G. D'Angelo; A. Peplinski

    2007-06-21

    Vortices in protoplanetary disks can capture solid particles and form planetary cores within shorter timescales than those involved in the standard core-accretion model. We investigate vortex generation in thin unmagnetized protoplanetary disks with an embedded giant planet with planet to star mass ratio $10^{-4}$ and $10^{-3}$. Two-dimensional hydrodynamical simulations of a protoplanetary disk with a planet are performed using two different numerical methods. The results of the non-linear simulations are compared with a time-resolved modal analysis of the azimuthally averaged surface density profiles using linear perturbation theory. Finite-difference methods implemented in polar coordinates generate vortices moving along the gap created by Neptune-mass to Jupiter-mass planets. The modal analysis shows that unstable modes are generated with growth rate of order $0.3 \\Omega_K$ for azimuthal numbers m=4,5,6, where $\\Omega_K$ is the local Keplerian frequency. Shock-capturing Cartesian-grid codes do not generate very much vorticity around a giant planet in a standard protoplanetary disk. Modal calculations confirm that the obtained radial profiles of density are less susceptible to the growth of linear modes on timescales of several hundreds of orbital periods. Navier-Stokes viscosity of the order $\

  7. Magnetorotational instability, current relaxation, and current-vortex sheet

    SciTech Connect (OSTI)

    Silveira, F. E. M. [Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Rua Santa Adélia, 166, CEP 09210-170, Bairro Bangu, Santo André, SP (Brazil)] [Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Rua Santa Adélia, 166, CEP 09210-170, Bairro Bangu, Santo André, SP (Brazil); Galvão, R. M. O. [Instituto de Física, Universidade de São Paulo, Rua do Matão, Travessa R, 187, CEP 05508-090, Cidade Universitária, São Paulo, SP (Brazil)] [Instituto de Física, Universidade de São Paulo, Rua do Matão, Travessa R, 187, CEP 05508-090, Cidade Universitária, São Paulo, SP (Brazil)

    2013-08-15

    The conjugate effect of current relaxation and of current-vortex sheet formation on the magnetorotational instability is explored in a conducting fluid. It is found that the relative amplification of the magnetic viscosity from marginal stability to the instability determined by the maximum growth rate is around 924% when resistive effects dominate, while the corresponding quantity is around 220% in the ideal limit. This shows that the conjugate influence is much more efficient to amplify the magnetic viscosity than just the effect due to the standard magnetic tension. It is also found that the magnitude of the magnetic viscosity is effectively enhanced by the conjugate influence. The results presented here may contribute to the understanding of the various processes that play a significant role in the mechanism of anomalous viscosity observed in Keplerian disks. It is argued that the new effect shall be relevant in thin accretion disks. It is also mentioned that the proposed formulation may be of interest for some theories of magnetic reconnection. Possible extensions of this work are suggested.

  8. Search for Stripes in Antiferromagnetic Lightly Hole-Doped YBa2Cu3O6: An Electron Spin Resonance and Infrared Tranmission Study

    SciTech Connect (OSTI)

    Janossy,A.; Nagy, K.; Feher, T.; Mihaly, L.; Erb, A.

    2007-01-01

    We present a series of electron spin resonance (ESR) and infrared transmission experiments in antiferromagnetic (AF), lightly hole-doped YBa{sub 2}Cu{sub 3}O{sub 6} in search for the effect of a spatially inhomogeneous ground state on the magnetic and electric properties. Crystal compositions were Ca{sub x}Gd{sub y}Y{sub 1-x-y}Ba{sub 2}Cu{sub 3}O{sub 6} with x=0 , 0.008, 0.02, and 0.03 and y{approx}0.01 . Gd{sup 3+} ESR satellites from sites with first-neighbor Ca atoms show that holes are not preferentially localized at low temperatures in the vicinity of Ca dopants. We mapped by multifrequency Gd{sup 3+} ESR the AF domain structure as a function of hole concentration, temperature, and magnetic fields up to 8T . We attribute the hole-doping-induced rotation of the magnetic easy axis from collateral to diagonal (with respect to the tetragonal CuO{sub 2} lattice) to the pinning of the AF magnetization to a static modulation or a phase-separated network of the hole density. The dominantly fourfold symmetry of pinning suggests that the hole density network has this symmetry also and is not an array of stripes. At higher temperatures the pinning to the diagonal direction becomes weak and the possibility of domain wall fluctuations is discussed. There is no magnetic field dependence and no in-plane anisotropy of the infrared transmission polarized in the CuO{sub 2} planes in an x=0.02 crystal placed in magnetic fields up to 12T . Thus, the network of holes is rigid and is not affected by magnetic fields that are, however, strong enough to rotate the AF magnetization into a single domain.

  9. A Robust Numerical Method for Integration of Point-Vortex Trajectories in Two Dimensions

    E-Print Network [OSTI]

    Spencer A. Smith; Bruce M. Boghosian

    2010-11-19

    The venerable 2D point-vortex model plays an important role as a simplified version of many disparate physical systems, including superfluids, Bose-Einstein condensates, certain plasma configurations, and inviscid turbulence. This system is also a veritable mathematical playground, touching upon many different disciplines from topology to dynamic systems theory. Point-vortex dynamics are described by a relatively simple system of nonlinear ODEs which can easily be integrated numerically using an appropriate adaptive time stepping method. As the separation between a pair of vortices relative to all other inter-vortex length scales decreases, however, the computational time required diverges. Accuracy is usually the most discouraging casualty when trying to account for such vortex motion, though the varying energy of this ostensibly Hamiltonian system is a potentially more serious problem. We solve these problems by a series of coordinate transformations: We first transform to action-angle coordinates, which, to lowest order, treat the close pair as a single vortex amongst all others with an internal degree of freedom. We next, and most importantly, apply Lie transform perturbation theory to remove the higher-order correction terms in succession. The overall transformation drastically increases the numerical efficiency and ensures that the total energy remains constant to high accuracy.

  10. Transition between vortex rings and MAP solutions for electrically charged magnetic solutions

    SciTech Connect (OSTI)

    Wong, Khai-Ming; Soltanian, Amin; Teh, Rosy

    2014-03-05

    We consider the bifurcation and transition of axially symmetric monopole-antimonopole pair (MAP) and vortex ring solutions in the presence of electric charge for the SU(2) Yang-Mills-Higgs field theory. Here we investigate the properties of MAP/vortex ring solutions with n = 3,? = 0.65, for different Higgs field strength ?. For ? < 4.93, there is only one fundamental branch of vortex ring solution, but at the critical value of ?{sub b} = 4.93, branching happens and 2 sets of new solutions appeared. The new branch with less energy is a full MAP solution while the branch with higher energy contains MAP at the beginning and separation between poles of MAP on the z-axis reduces gradually and at another critical value of ?{sub t} = 14.852, they merge together at z = 0. Beyond this point the solutions change to the vortex ring solutions and a transitions between MAP and vortex ring solutions happens at this branch.

  11. Bow-wave-like hydraulic jump and horseshoe vortex around an obstacle in a supercritical open channel flow

    E-Print Network [OSTI]

    Boyer, Edmond

    Bow-wave-like hydraulic jump and horseshoe vortex around an obstacle in a supercritical open the obstacle, two main flow structures are observed: i a hydraulic jump in the near-surface region and ii turbulent regime , the detachment length of the hydraulic jump exceeds the one of the horseshoe vortex

  12. A vortex level set method for the two-way coupling of an incompressible fluid with colliding rigid bodies

    E-Print Network [OSTI]

    Cottet, Georges-Henri

    in a non laminar flow. Here we consider a different approach. The fluid­ solid system is considered rights reserved. Keywords: Incompressible flow; Fluid­solid interaction; Vortex method; Level set methodA vortex level set method for the two-way coupling of an incompressible fluid with colliding rigid

  13. Effect of tube spacing on the vortex shedding characteristics of laminar flow past an inline tube array: A numerical study

    E-Print Network [OSTI]

    Luo, Xiaoyu

    Effect of tube spacing on the vortex shedding characteristics of laminar flow past an inline tube the tubes. Complex flow dynamic phenomena such as reattachment of shear layers, in- duced separation, vortex Accepted 27 October 2008 Available online 14 November 2008 a b s t r a c t The effect of tube spacing

  14. Two-dimensional model problem to explain counter-rotating vortex pair formation in a transverse jet

    E-Print Network [OSTI]

    Mahesh, Krishnan

    Two-dimensional model problem to explain counter-rotating vortex pair formation in a transverse jet A two-dimensional model problem is used to study the evolution of the cross section of a transverse jet and the counter-rotating vortex pair CVP . The solution to the model problem shows deformation of the jet similar

  15. NMR and SR study of magnetic dilution in the triangular Heisenberg antiferromagnet This article has been downloaded from IOPscience. Please scroll down to see the full text article.

    E-Print Network [OSTI]

    Paris-Sud 11, Université de

    the specific heat peak at TN 41 K, and characterized by a peak of the relaxation rate that appears at 0.75TNNMR and SR study of magnetic dilution in the triangular Heisenberg antiferromagnet NaCrO 2 Collections Journals About Contact us My IOPscience #12;NMR and µSR study of magnetic dilution

  16. Electron trapping by a current vortex F. Bentosela, a;b P. Exner, c;d and V.A. Zagrebnov a;b

    E-Print Network [OSTI]

    simpler example involves a Pauli electron interacting with a flux tube modelling a vortex magnetic fieldElectron trapping by a current vortex F. Bentosela, a;b P. Exner, c;d and V.A. Zagrebnov a;b a with the magnetic field due to an electric current forming a localized rotationally symmetric vortex. We show

  17. Role of the Vortex-Core Energy on the Berezinskii-Kosterlitz-Thouless Transition in Thin Films of NbN

    E-Print Network [OSTI]

    Raychaudhuri, Pratap

    Role of the Vortex-Core Energy on the Berezinskii-Kosterlitz-Thouless Transition in Thin Films-Kosterlitz-Thouless (BKT) transition in thin films of NbN at various film thickness, by probing the effect of vortex played by the vortex-core energy in determining the characteristic signatures of the BKT physics, and we

  18. Transitions between turbulent and laminar superfluid vorticity states in the outer core of a neutron star

    E-Print Network [OSTI]

    C. Peralta; A. Melatos; M. Giacobello; A. Ooi

    2006-07-08

    We investigate the global transition from a turbulent state of superfluid vorticity to a laminar state, and vice versa, in the outer core of a neutron star. By solving numerically the hydrodynamic Hall-Vinen-Bekarevich-Khalatnikov equations for a rotating superfluid in a differentially rotating spherical shell, we find that the meridional counterflow driven by Ekman pumping exceeds the Donnelly-Glaberson threshold throughout most of the outer core, exciting unstable Kelvin waves which disrupt the rectilinear vortex array, creating a vortex tangle. In the turbulent state, the torque exerted on the crust oscillates, and the crust-core coupling is weaker than in the laminar state. This leads to a new scenario for the rotational glitches observed in radio pulsars: a vortex tangle is sustained in the differentially rotating outer core by the meridional counterflow, a sudden spin-up event brings the crust and core into corotation, the vortex tangle relaxes back to a rectilinear vortex array, then the crust spins down electromagnetically until enough meridional counterflow builds up to reform a vortex tangle. The turbulent-laminar transition can occur uniformly or in patches; the associated time-scales are estimated from vortex filament theory. We calculate numerically the global structure of the flow with and without an inviscid superfluid component, for Hall-Vinen and Gorter-Mellink forms of the mutual friction. We also calculate the post-glitch evolution of the angular velocity of the crust and its time derivative, and compare the results with radio pulse timing data, predicting a correlation between glitch activity and Reynolds number.

  19. Magnetic monopole versus vortex as gauge-invariant topological objects for quark confinement

    E-Print Network [OSTI]

    Kondo, Kei-Ichi; Shinohara, Toru; Shibata, Akihiro; Kato, Seikou

    2015-01-01

    First, we give a gauge-independent definition of chromomagnetic monopoles in $SU(N)$ Yang-Mills theory which is derived through a non-Abelian Stokes theorem for the Wilson loop operator. Then we discuss how such magnetic monopoles can give a nontrivial contribution to the Wilson loop operator for understanding the area law of the Wilson loop average. Next, we discuss how the magnetic monopole condensation picture are compatible with the vortex condensation picture as another promising scenario for quark confinement. We analyze the profile function of the magnetic flux tube as the non-Abelian vortex solution of $U(N)$ gauge-Higgs model, which is to be compared with numerical simulations of the $SU(N)$ Yang-Mills theory on a lattice. This analysis gives an estimate of the string tension based on the vortex condensation picture, and possible interactions between two non-Abelian vortices.

  20. Spectro-Polarimetric Properties of Small-Scale Plasma Eruptions Driven by Magnetic Vortex Tubes

    E-Print Network [OSTI]

    Kitiashvili, Irina N

    2014-01-01

    Highly turbulent nature of convection on the Sun causes strong multi-scale interaction of subsurface layers with the photosphere and chromosphere. According to realistic 3D radiative MHD numerical simulations ubiquitous small-scale vortex tubes are generated by turbulent flows below the visible surface and concentrated in the intergranular lanes. The vortex tubes can capture and amplify magnetic field, penetrate into chromospheric layers and initiate quasi-periodic flow eruptions that generates Alfv\\'enic waves, transport mass and energy into the solar atmosphere. The simulations revealed high-speed flow patterns, and complicated thermodynamic and magnetic structures in the erupting vortex tubes. The spontaneous eruptions are initiated and driven by strong pressure gradients in the near-surface layers, and accelerated by the Lorentz force in the low chromosphere. In this paper, the simulation data are used to further investigate the dynamics of the eruptions, their spectro-polarimetric characteristics for the...

  1. Magnetic monopole versus vortex as gauge-invariant topological objects for quark confinement

    E-Print Network [OSTI]

    Kei-Ichi Kondo; Takaaki Sasago; Toru Shinohara; Akihiro Shibata; Seikou Kato

    2015-08-08

    First, we give a gauge-independent definition of chromomagnetic monopoles in $SU(N)$ Yang-Mills theory which is derived through a non-Abelian Stokes theorem for the Wilson loop operator. Then we discuss how such magnetic monopoles can give a nontrivial contribution to the Wilson loop operator for understanding the area law of the Wilson loop average. Next, we discuss how the magnetic monopole condensation picture are compatible with the vortex condensation picture as another promising scenario for quark confinement. We analyze the profile function of the magnetic flux tube as the non-Abelian vortex solution of $U(N)$ gauge-Higgs model, which is to be compared with numerical simulations of the $SU(N)$ Yang-Mills theory on a lattice. This analysis gives an estimate of the string tension based on the vortex condensation picture, and possible interactions between two non-Abelian vortices.

  2. Vortex combustor for low NOx emissions when burning lean premixed high hydrogen content fuel

    DOE Patents [OSTI]

    Steele, Robert C. (Woodinville, WA); Edmonds, Ryan G. (Renton, WA); Williams, Joseph T. (Kirkland, WA); Baldwin, Stephen P. (Winchester, MA)

    2009-10-20

    A trapped vortex combustor. The trapped vortex combustor is configured for receiving a lean premixed gaseous fuel and oxidant stream, where the fuel includes hydrogen gas. The trapped vortex combustor is configured to receive the lean premixed fuel and oxidant stream at a velocity which significantly exceeds combustion flame speed in a selected lean premixed fuel and oxidant mixture. The combustor is configured to operate at relatively high bulk fluid velocities while maintaining stable combustion, and low NOx emissions. The combustor is useful in gas turbines in a process of burning synfuels, as it offers the opportunity to avoid use of diluent gas to reduce combustion temperatures. The combustor also offers the possibility of avoiding the use of selected catalytic reaction units for removal of oxides of nitrogen from combustion gases exiting a gas turbine.

  3. Shear Banding and Spatiotemporal Oscillations in Vortex Matter in Nanostructured Superconductors

    E-Print Network [OSTI]

    C. Reichhardt; C. J. Olson Reichhardt

    2009-12-16

    We propose a simple nanostructured pinning array geometry where a rich variety of complex vortex shear banding phenomena can be realized. A single row of pinning sites is removed from a square pinning array. Shear banding effects arise when vortex motion in the pin-free channel nucleates motion of vortices in the surrounding pinned regions, creating discrete steps in the vortex velocity profile away from the channel. Near the global depinning transition, the width of the band of moving vortices undergoes oscillations or fluctuations that can span the entire system. We use simulations to show that these effects should be observable in the transport properties of the system. Similar large oscillations and shear banding effects are known to occur for sheared complex fluids in which different dynamical phases coexist.

  4. Reduction of vortex induced forces and motion through surface roughness control

    DOE Patents [OSTI]

    Bernitsas, Michael M; Raghavan, Kamaldev

    2014-04-01

    Roughness is added to the surface of a bluff body in a relative motion with respect to a fluid. The amount, size, and distribution of roughness on the body surface is controlled passively or actively to modify the flow around the body and subsequently the Vortex Induced Forces and Motion (VIFM). The added roughness, when designed and implemented appropriately, affects in a predetermined way the boundary layer, the separation of the boundary layer, the level of turbulence, the wake, the drag and lift forces, and consequently the Vortex Induced Motion (VIM), and the fluid-structure interaction. The goal of surface roughness control is to decrease/suppress Vortex Induced Forces and Motion. Suppression is required when fluid-structure interaction becomes destructive as in VIM of flexible cylinders or rigid cylinders on elastic support, such as underwater pipelines, marine risers, tubes in heat exchangers, nuclear fuel rods, cooling towers, SPAR offshore platforms.

  5. Random Vortex-Street Model for a Self-Similar Plane Turbulent Jet

    E-Print Network [OSTI]

    Victor L'vov; Anna Pomyalov; Itamar Procaccia; Rama Govindarajan

    2008-03-18

    We ask what determines the (small) angle of turbulent jets. To answer this question we first construct a deterministic vortex-street model representing the large scale structure in a self-similar plane turbulent jet. Without adjustable parameters the model reproduces the mean velocity profiles and the transverse positions of the large scale structures, including their mean sweeping velocities, in a quantitative agreement with experiments. Nevertheless the exact self similar arrangement of the vortices (or any other deterministic model) necessarily leads to a collapse of the jet angle. The observed (small) angle results from a competition between vortex sweeping tending to strongly collapse the jet and randomness in the vortex structure, with the latter resulting in a weak spreading of the jet.

  6. Vortex combustor for low NOX emissions when burning lean premixed high hydrogen content fuel

    DOE Patents [OSTI]

    Steele, Robert C; Edmonds, Ryan G; Williams, Joseph T; Baldwin, Stephen P

    2012-11-20

    A trapped vortex combustor. The trapped vortex combustor is configured for receiving a lean premixed gaseous fuel and oxidant stream, where the fuel includes hydrogen gas. The trapped vortex combustor is configured to receive the lean premixed fuel and oxidant stream at a velocity which significantly exceeds combustion flame speed in a selected lean premixed fuel and oxidant mixture. The combustor is configured to operate at relatively high bulk fluid velocities while maintaining stable combustion, and low NOx emissions. The combustor is useful in gas turbines in a process of burning synfuels, as it offers the opportunity to avoid use of diluent gas to reduce combustion temperatures. The combustor also offers the possibility of avoiding the use of selected catalytic reaction units for removal of oxides of nitrogen from combustion gases exiting a gas turbine.

  7. Single-vortex pinning and penetration depth in superconducting NdFeAsO1-xFx

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhang, Jessie T.; Kim, Jeehoon; Huefner, Magdalena; Ye, Cun; Kim, Stella; Canfield, Paul C.; Prozorov, Ruslan; Auslaender, Ophir M.; Hoffman, Jennifer E.

    2015-10-12

    We use a magnetic force microscope (MFM) to investigate single vortex pinning and penetration depth in NdFeAsO1-xFx, one of the highest-Tc iron-based superconductors. In fields up to 20 Gauss, we observe a disordered vortex arrangement, implying that the pinning forces are stronger than the vortex-vortex interactions. We measure the typical force to depin a single vortex, Fdepin ? 4.5 pN, corresponding to a critical current up to Jc ? 7×105 A/cm2. As a result, our MFM measurements allow the first local and absolute determination of the superconducting in-plane penetration depth in NdFeAsO1-xFx, ?ab = 320 ± 60 nm, which ismore »larger than previous bulk measurements.« less

  8. Relativistic Electron Vortex Beams: Angular Momentum and Spin-Orbit Interaction

    E-Print Network [OSTI]

    Konstantin Y. Bliokh; Mark R. Dennis; Franco Nori

    2011-09-11

    Motivated by the recent discovery of electron vortex beams carrying orbital angular momentum (AM), we construct exact Bessel-beam solutions of the Dirac equation. They describe relativistic and nonparaxial corrections to the scalar electron beams. We describe the spin and orbital AM of the electron with Berry-phase corrections and predict the intrinsic spin-orbit coupling in free space. This can be observed as a spin-dependent probability distribution of the focused electron vortex beams. Moreover, the magnetic moment is calculated, which shows different $g$-factors for spin and orbital AM and also contains the Berry-phase correction.

  9. Deep sub-nanosecond reversal of vortex cores confined in a spin-wave potential well

    SciTech Connect (OSTI)

    Dong, Xinwei; Wang, Zhenyu; Wang, Ruifang, E-mail: wangrf@xmu.edu.cn [Department of Physics and Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen 361005 (China)

    2014-03-17

    A spin-wave potential well is created in a permalloy nanodisk by setting up a cylindrical cavity in the center of the sample. We then apply a single-harmonic external magnetic field perpendicular to the disk plane to switch the vortex polarity of the sample. Our micromagnetic numerical studies establish that the effective spin-wave confinement by the potential well leads to much stronger magnetization oscillation in the sample. Therefore, the vortex core can be reversed well below 200 ps and over a wide range of field frequency. Our findings present an additional efficient means for ultrafast switching of magnetic vortices.

  10. Antiferromagnetic half-metals, gapless half-metals, and spin gapless semiconductors: The D0{sub 3}-type Heusler alloys

    SciTech Connect (OSTI)

    Gao, G. Y. Yao, Kai-Lun

    2013-12-02

    High-spin-polarization materials are desired for the realization of high-performance spintronic devices. We combine recent experimental and theoretical findings to theoretically design several high-spin-polarization materials in binary D0{sub 3}-type Heusler alloys: gapless (zero-gap) half-metallic ferrimagnets of V{sub 3}Si and V{sub 3}Ge, half-metallic antiferromagnets of Mn{sub 3}Al and Mn{sub 3}Ga, half-metallic ferrimagnets of Mn{sub 3}Si and Mn{sub 3}Ge, and a spin gapless semiconductor of Cr{sub 3}Al. The high spin polarization, zero net magnetic moment, zero energy gap, and slight disorder compared to the ternary and quaternary Heusler alloys make these binary materials promising candidates for spintronic applications. All results are obtained by the electronic structure calculations from first-principles.

  11. Synthesis, structure, and magnetic properties of spin-1/2 kagomé antiferromagnets

    E-Print Network [OSTI]

    Nytko, Emily A

    2008-01-01

    Stoichiometrically pure S = 1/2 Cu2+ kagomé materials have been synthesized. Such materials provide an ideal venue for exploration of quantum states on a kagomé because they exhibit strong geometric spin frustration and ...

  12. Vortex reconnections in atomic condensates at finite temperature A. J. Allen1

    E-Print Network [OSTI]

    Zuccher, Simone

    superfluid turbu- lence, a phenomenon recently also reported in trapped atomic Bose­Einstein condensates, vortex dynamics, quantum turbulence, Bose-Einstein condensates, Superfluid He In classical hydrodynamics 3 He and atomic Bose­Einstein condensates (BECs) is currently debated. For example, one would like

  13. Detection of vortex tubes in solar granulation from observations with Sunrise

    E-Print Network [OSTI]

    Steiner, O; Gonzalez, N Bello; Nutto, Ch; Rezaei, R; Pillet, V Martinez; Navarro, J A Bonet; Iniesta, J C del Toro; Domingo, V; Solanki, S K; Knolker, M; Schmidt, W; Barthol, P; Gandorfer, A

    2010-01-01

    We have investigated a time series of continuum intensity maps and corresponding Dopplergrams of granulation in a very quiet solar region at the disk center, recorded with the Imaging Magnetograph eXperiment (IMaX) on board the balloon-borne solar observatory Sunrise. We find that granules frequently show substructure in the form of lanes composed of a leading bright rim and a trailing dark edge, which move together from the boundary of a granule into the granule itself. We find strikingly similar events in synthesized intensity maps from an ab initio numerical simulation of solar surface convection. From cross sections through the computational domain of the simulation, we conclude that these `granular lanes' are the visible signature of (horizontally oriented) vortex tubes. The characteristic optical appearance of vortex tubes at the solar surface is explained. We propose that the observed vortex tubes may represent only the large-scale end of a hierarchy of vortex tubes existing near the solar surface.

  14. The tangential velocity profile and momentum transfer within a microgravity, vortex separator 

    E-Print Network [OSTI]

    Ellis, Michael Clay

    2009-05-15

    &M University (TAMU) have developed a microgravity vortex separator (MVS) capable of handling both a wide range of inlet conditions and changes in these conditions. To optimize the MVS design, the effects of nozzle area, separator geometry, and inlet flow rate...

  15. RESEARCH ARTICLE Drag and lift reduction of a 3D bluff-body using active vortex

    E-Print Network [OSTI]

    Wesfreid, José Eduardo

    apparatus (chemical industry, energy production). From the academic point of view, it is an exciting-up with motorized vortex generators is proposed. Thanks to this active device. The optimal configurations depending academic and industrial research. From the indus- trial point of view, flow control is a way to increase

  16. Model of coarsening and vortex formation in vibrated granular rods Igor S. Aranson

    E-Print Network [OSTI]

    Tsimring, Lev S.

    Model of coarsening and vortex formation in vibrated granular rods Igor S. Aranson Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 Lev S. Tsimring Institute for Nonlinear Science spontaneous formation of the long-range orientational order and large- scale vortices in a system of vibrated

  17. 2094 OPTICS LETTERS / Vol. 28, No. 21 / November 1, 2003 Fundamental and vortex solitons in a

    E-Print Network [OSTI]

    Yang, Jianke

    2094 OPTICS LETTERS / Vol. 28, No. 21 / November 1, 2003 Fundamental and vortex solitons in a two-dimensional optical lattice Jianke Yang Department of Mathematics and Statistics, University of Vermont, Burlington-dimensional optically induced waveguide array are reported. In the strong localization regime the fundamental soliton

  18. "Development of a Free Vortex Wake Method Code for Offshore Floating Wind Turbines"

    E-Print Network [OSTI]

    Mountziaris, T. J.

    "Development of a Free Vortex Wake Method Code for Offshore Floating Wind Turbines" Andrew Sciotti Professor Matthew Lackner Shujian Liu Offshore floating wind turbines (OFWTs) require a unique aerodynamic in refining current mathematical models of offshore wind turbines while also allowing efficient simulations

  19. Sediment resuspension and erosion by vortex rings R. J. Munro,1,a

    E-Print Network [OSTI]

    Dalziel, Stuart

    Sediment resuspension and erosion by vortex rings R. J. Munro,1,a N. Bethke,2 and S. B. Dalziel2 1; accepted 26 January 2009; published online 8 April 2009 Particle resuspension and erosion induced-ring propagation speed. The critical conditions for resuspension whereby particles are only just resuspended were

  20. Vortex Ring Interaction with a Particle Layer: Implications for Sediment Transport

    E-Print Network [OSTI]

    Dalziel, Stuart

    resuspension has been studied much less. This is an important mechanism, however, as it represents an integral conducted to study particle resuspension by vortex rings colliding with a particle bed. The dynamics at the resuspension onset are investigated, showing that the deformable particle bed resembles a free slip boundary

  1. Microoptomechanical pumps assembled and driven by holographic optical vortex Kosta Ladavac

    E-Print Network [OSTI]

    Grier, David

    Microoptomechanical pumps assembled and driven by holographic optical vortex arrays Kosta Ladavac into dynamically reconfigurable microoptomechanical pumps assembled by optical gradient forces and actuated systems has created a need for new meth­ ods to pump and steer fluids through micrometer­scale channels

  2. Microoptomechanical pumps assembled and driven by holographic optical vortex Kosta Ladavac

    E-Print Network [OSTI]

    Grier, David

    Microoptomechanical pumps assembled and driven by holographic optical vortex arrays Kosta Ladavac into dynamically reconfigurable microoptomechanical pumps assembled by optical gradient forces and actuated systems has created a need for new meth- ods to pump and steer fluids through micrometer-scale channels

  3. Hierarchical Colloidal Vortex Rings in a Constant Electric Field Yilong Han and David G. Grier

    E-Print Network [OSTI]

    Grier, David

    in the bulk of charge­stabilized colloidal suspensions when electrohydrodynamic forces due to constant appliedHierarchical Colloidal Vortex Rings in a Constant Electric Field Yilong Han and David G. Grier used [1, 2] to study interfacial col­ loidal electrokinetic phenomena. An aqueous suspension

  4. Hierarchical Colloidal Vortex Rings in a Constant Electric Field Yilong Han and David G. Grier

    E-Print Network [OSTI]

    Grier, David

    in the bulk of charge-stabilized colloidal suspensions when electrohydrodynamic forces due to constant appliedHierarchical Colloidal Vortex Rings in a Constant Electric Field Yilong Han and David G. Grier used [1, 2] to study interfacial col- loidal electrokinetic phenomena. An aqueous suspension

  5. Self-consistent anisotropic oscillator with cranked angular and vortex velocities

    E-Print Network [OSTI]

    G. Rosensteel

    1992-11-05

    The Kelvin circulation is the kinematical Hermitian observable that measures the true character of nuclear rotation. For the anisotropic oscillator, mean field solutions with fixed angular momentum and Kelvin circulation are derived in analytic form. The cranking Lagrange multipliers corresponding to the two constraints are the angular and vortex velocities. Self-consistent solutions are reported with a constraint to constant volume.

  6. Vortex-Pair Dynamics in Anisotropic Bistable Media: A Kinematic Approach Aric Hagberg1

    E-Print Network [OSTI]

    Meron, Ehud

    Alamos, New Mexico 87545, USA 2 Department of Solar Energy and Environmental Physics, BIDR, Ben Gurion type upon rotation by =2. We study vortex-pair dynamics by deriving kinematic equations for a front with contour lines that form a closed loop. Equations of this kind, but for isotropic systems and infinite

  7. A Lagrangian approach to identifying vortex pinch-off Clara O'Farrell1

    E-Print Network [OSTI]

    Dabiri, John O.

    A Lagrangian approach to identifying vortex pinch-off Clara O'Farrell1 and John O. Dabiri2 1 Control and Dynamical Systems, California Institute of Technology, Pasadena, California 91125, USA 2 Graduate Aeronautical Laboratories and Bioengineering, California Institute of Technology, Pasadena

  8. Under consideration for publication in J. Fluid Mech. 1 Drop impact into a deep pool: vortex

    E-Print Network [OSTI]

    Deegan, Robert

    Under consideration for publication in J. Fluid Mech. 1 Drop impact into a deep pool: vortex of Michigan, Ann Arbor, Michigan 48109, USA 2 Division of Physical Sciences and Engineering & Clean Combustion Arabia 3 Physics of Fluids Group, Faculty of Science and Technology, Mesa+ Institute, University

  9. Instabilities due a vortex at a density interface: gravitational and centrifugal effects

    E-Print Network [OSTI]

    Dixit, Harish

    Instabilities due a vortex at a density interface: gravitational and centrifugal effects Harish N showed recently that the flow is subject to centrifugal Rayleigh-Taylor and spiral Kelvin for example [5]). In the absence of gravity, centrifugal forces are predominant, and we showed recently [4

  10. Aging memory and glassiness of a driven vortex , Guohong Li1

    E-Print Network [OSTI]

    Andrei, Eva Y.

    1 Aging memory and glassiness of a driven vortex system. Xu Du1 , Guohong Li1 , Eva Y. Andrei1 , M memory, aging and nonlinear-dynamics. Glasses[1-11], interfaces[12] and fractures are some examples[13 the deviation from equilibrium. After removing the force, the system ages with time and its subsequent response

  11. Quantum ground state effect on fluctuation rates in nano-patterned superconducting structures

    SciTech Connect (OSTI)

    Eftekharian, Amin; Jafari Salim, Amir; University of Waterloo, 200 University Ave West, Waterloo, Ontario N2L 3G1 ; Atikian, Haig; Akhlaghi, Mohsen K.; Hamed Majedi, A.

    2013-12-09

    In this Letter, we present a theoretical model with experimental verifications to describe the abnormal behaviors of the measured fluctuation rates occurring in nano-patterned superconducting structures below the critical temperature. In the majority of previous works, it is common to describe the fluctuation rate by defining a fixed ground state or initial state level for the singularities (vortex or vortex-antivortex pairs), and then employing the well-known rate equations to calculate the liberation rates. Although this approach gives an acceptable qualitative picture, without utilizing free parameters, all the models have been inadequate in describing the temperature dependence of the rate for a fixed width or the width dependence of the rate for a fixed temperature. Here, we will show that by defining a current-controlled ground state level for both the vortex and vortex-antivortex liberation mechanisms, the dynamics of these singularities are described for a wide range of temperatures and widths. According to this study, for a typical strip width, not only is the vortex-antivortex liberation higher than the predicted rate, but also quantum tunneling is significant in certain conditions and can not be neglected.

  12. Vortex lattices in the superconducting phases of doped topological...

    Office of Scientific and Technical Information (OSTI)

    Sponsoring Org: USDOE Country of Publication: United States Language: English Word Cloud More Like This Free Publicly Accessible Full Text Publisher's Accepted Manuscript at...

  13. Surface driven effects on magnetic properties of antiferromagnetic LaFeO{sub 3} nanocrystalline ferrite

    SciTech Connect (OSTI)

    Sendil Kumar, A. E-mail: anilb42@gmail.com; Manivel Raja, M.; Bhatnagar, Anil K. E-mail: anilb42@gmail.com

    2014-09-21

    LaFeO{sub 3} nanocrystalline ferrites were synthesized through sol-gel method in different size distributions and the effect of finite size on magnetic properties is investigated. Results of magnetization and Mössbauer measurements show that superparamagnetism and weak ferromagnetic behavior in some of the size distributions. The origin of the superparamagnetism is from fine particles similar to ferromagnetic single domains and the weak ferromagnetism comes from surface spin disorder caused by Dzyaloshinskii-Moriya interaction. The magnetic ground state of LaFeO{sub 3} nanoparticles differs from that of bulk, and the ground state is dictated by the finite size effect because density of states depends on the dimensionality of the sample.

  14. Development of vortex state in circular magnetic nanodots: Theory and experiment RID A-9247-2009 

    E-Print Network [OSTI]

    Mejia-Lopez, J.; Altbir, D.; Landeros, P.; Escrig, J.; Romero, A. H.; Roshchin, Igor V.; Li, C-P; Fitzsimmons, M. R.; Batlle, X.; Schuller, Ivan K.

    2010-01-01

    in a variety of spintronics and magnetic storage applications, including magnetic bit- patterned media and magnetic random access memory. One of the most studied types of such structures are nanoscaled disks denoted as ?nanodots? which have been...

  15. PUBLISHED ONLINE: 18 JANUARY 2009 DOI: 10.1038/NPHYS1177 Evidence for an oscillating soliton/vortex ring by

    E-Print Network [OSTI]

    Loss, Daniel

    soliton/vortex ring by density engineering of a Bose­Einstein condensate I. Shomroni, E. Lahoud, S. Levy and J. Steinhauer* When two Bose­Einstein condensates collide with high collisional energy

  16. A scatter diagram approach to the selection of design currents for prediction of marine riser vortex-induced vibration

    E-Print Network [OSTI]

    Donnelly, Jessica Mary

    2004-01-01

    This paper describes a scatter diagram approach for the classification of large numbers of current profiles for use in the prediction of riser fatigue damage due to vortex-induced vibration. Scatter diagrams have long been ...

  17. Contributions of the wall boundary layer to the formation of the counter-rotating vortex pair in transverse jets

    E-Print Network [OSTI]

    Schlegel, Fabrice

    Using high-resolution 3-D vortex simulations, this study seeks a mechanistic understanding of vorticity dynamics in transverse jets at a finite Reynolds number. A full no-slip boundary condition, rigorously formulated in ...

  18. On the peculiar properties of triangular-chain EuCr{sub 3}(BO{sub 3}){sub 4} antiferromagnet

    SciTech Connect (OSTI)

    Gondek, ?.; Szytu?a, A.; Przewo?nik, J.; ?ukrowski, J.; Prokhorov, A.; Chernush, L.; Zubov, E.; Dyakonov, V.; Tyvanchuk, Yu.

    2014-02-15

    In this paper we report studies on EuCr{sub 3}(BO{sub 3}){sub 4} compound, that is a member of newly discovered family of huntite-related specimens for non-linear optics. For the first time, the uncommon temperature dependence of the EuCr{sub 3}(BO{sub 3}){sub 4} lattice parameters is reported. Additionally, the magnetism of this compound is extremely interesting. Namely, a possible interplay in between potentially magnetic rare-earth ions and 3d metal stacked within quasi-1D chain that can lead to a great variety of magnetic behaviour. Indeed, in our studies we have found 3D-long range ordering with metamagnetic behaviour, while at higher temperature the magnetic chains become uncoupled. - Graphical abstract: Torsion-like vibrations are the key to understand negative thermal expansion along the a-axis. Display Omitted - Highlights: • EuCr{sub 3}(BO{sub 3}){sub 4} is a peculiar triangular-chain antiferromagnet. • Rare earth sublattice is non-magnetic with Eu{sup 3+} configuration. • Cr{sup 3+} magnetic moments show 1-D behaviour along with spin fluctuations. • Torsion vibrations of Cr triangular tubes lead to anomalous expansion of unit cell.

  19. High-precision determination of low-energy effective parameters for a two-dimensional Heisenberg quantum antiferromagnet

    SciTech Connect (OSTI)

    Jiang, F.-J.; Wiese, U.-J.

    2011-04-15

    The two-dimensional (2D) spin-(1/2) Heisenberg antiferromagnet with exchange coupling J is investigated on a periodic square lattice of spacing a at very small temperatures using the loop-cluster algorithm. Monte Carlo data for the staggered and uniform susceptibilities are compared with analytic results obtained in the systematic low-energy effective field theory for the staggered magnetization order parameter. The low-energy parameters of the effective theory, i.e., the staggered magnetization density M{sub s}=0.307 43(1)/a{sup 2}, the spin stiffness {rho}{sub s}=0.180 81(11)J, and the spin wave velocity c=1.6586(3)Ja, are determined with very high precision. Our study may serve as a test case for the comparison of lattice quantum chromodynamics Monte Carlo data with analytic predictions of the chiral effective theory for pions and nucleons, which is vital for the quantitative understanding of the strong interaction at low energies.

  20. General rotating quantum vortex filaments in the low-temperature Svistunov model of the local induction approximation

    SciTech Connect (OSTI)

    Van Gorder, Robert A.

    2014-06-15

    In his study of superfluid turbulence in the low-temperature limit, Svistunov [“Superfluid turbulence in the low-temperature limit,” Phys. Rev. B 52, 3647 (1995)] derived a Hamiltonian equation for the self-induced motion of a vortex filament. Under the local induction approximation (LIA), the Svistunov formulation is equivalent to a nonlinear dispersive partial differential equation. In this paper, we consider a family of rotating vortex filament solutions for the LIA reduction of the Svistunov formulation, which we refer to as the 2D LIA (since it permits a potential formulation in terms of two of the three Cartesian coordinates). This class of solutions holds the well-known Hasimoto-type planar vortex filament [H. Hasimoto, “Motion of a vortex filament and its relation to elastica,” J. Phys. Soc. Jpn. 31, 293 (1971)] as one reduction and helical solutions as another. More generally, we obtain solutions which are periodic in the space variable. A systematic analytical study of the behavior of such solutions is carried out. In the case where vortex filaments have small deviations from the axis of rotation, closed analytical forms of the filament solutions are given. A variety of numerical simulations are provided to demonstrate the wide range of rotating filament behaviors possible. Doing so, we are able to determine a number of vortex filament structures not previously studied. We find that the solution structure progresses from planar to helical, and then to more intricate and complex filament structures, possibly indicating the onset of superfluid turbulence.

  1. Large amplitude spin torque vortex oscillations at zero external field using a perpendicular spin polarizer

    SciTech Connect (OSTI)

    Dussaux, A.; Rache Salles, B.; Jenkins, A. S.; Bortolotti, P.; Grollier, J.; Cros, V.; Fert, A.; Khvalkovskiy, A. V.; Kubota, H.; Fukushima, A.; Yakushiji, K.; Yuasa, S.

    2014-07-14

    We investigate the microwave response of a spin transfer vortex based oscillator in a magnetic tunnel junction with an in-plane reference layer combined with a spin valve with an out-of-plane magnetization spin polarizing layer. The main advantage of this perpendicular spin polarizer is to induce a large spin transfer force even at zero magnetic field, thus leading to a record emitted power (up to 0.6??W) associated to a very narrow spectral linewidth of a few hundreds of kHz. The characteristics of this hybrid vortex based spin transfer nano-oscillator obtained at zero field and room temperature are of great importance for applications based on rf spintronic devices as integrated and tunable microwave source and/or microwave detector.

  2. Observation of the Larmor and Gouy Rotations with Electron Vortex Beams

    E-Print Network [OSTI]

    Giulio Guzzinati; Peter Schattschneider; Konstantin Bliokh; Franco Nori; Jo Verbeeck

    2013-02-25

    Electron vortex beams carrying intrinsic orbital angular momentum (OAM) are produced in electron microscopes where they are controlled and focused using magnetic lenses. We observe various rotational phenomena arising from the interaction between the OAM and magnetic lenses. First, the Zeeman coupling, proportional to the OAM and magnetic field strength, produces an OAM-independent Larmor rotation of a mode superposition inside the lens. Second, hen passing through the focal plane, the electron beam acquires an additional Gouy phase dependent on the absolute value of the OAM. This brings about the Gouy rotation of the superposition image proportional to the sign of the OAM. A combination of the Larmor and Gouy effects can result in the addition (or subtraction) of rotations, depending on the OAM sign. This behaviour is unique to electron vortex beams and has no optical counterpart, as Larmor rotation occurs only for charged particles. Our experimental results are in agreement with recent theoretical predictions.

  3. Vortex Formation and Evolution in Planet Harboring Disks under Thermal Relaxation

    E-Print Network [OSTI]

    Gomes, A Lobo; Uribe, A L; Pinilla, P; Surville, C

    2015-01-01

    We study the evolution of planet-induced vortices in radially stratified disks, with initial conditions allowing for radial buoyancy. For this purpose we run global two dimensional hydrodynamical simulations, using the PLUTO code. Planet-induced vortices are a product of the Rossby wave instability (RWI) triggered in the edges of a planetary gap. In this work we assess the influence of radial buoyancy for the development of the vortices. We found that radial buoyancy leads to smoother planetary gaps, which generates weaker vortices. This effect is less pronounced for locally isothermal and quasi-isothermal (very small cooling rate) disks. We observed the formation of two generations of vortices. The first generation of vortices is formed in the outer wall of the planetary gap. The merged primary vortex induces accretion, depleting the mass on its orbit. This process creates a surface density enhancement beyond the primary vortex position. The second generation of vortices arise in this surface density enhance...

  4. Quasi-classical approximation in vortex filament dynamics. Integrable systems, gradient catastrophe and flutter

    E-Print Network [OSTI]

    B. G. Konopelchenko; G. Ortenzi

    2012-06-13

    Quasiclassical approximation in the intrinsic description of the vortex filament dynamics is discussed. Within this approximation the governing equations are given by elliptic system of quasi-linear PDEs of the first order. Dispersionless Da Rios system and dispersionless Hirota equation are among them. They describe motion of vortex filament with slow varying curvature and torsion without or with axial flow. Gradient catastrophe for governing equations is studied. It is shown that geometrically this catastrophe manifests as a fast oscillation of a filament curve around the rectifying plane which resembles the flutter of airfoils. Analytically it is the elliptic umbilic singularity in the terminology of the catastrophe theory. It is demonstrated that its double scaling regularization is governed by the Painleve' I equation.

  5. Weakening of the Stratospheric Polar Vortex by Arctic Sea-Ice Loss

    SciTech Connect (OSTI)

    Kim, Baek-Min; Son, Seok-Woo; Min, Seung-Ki; Jeong, Jee-Hoon; Kim, Seong-Joong; Zhang, Xiangdong; Shim, Taehyoun; Yoon, Jin-Ho

    2014-09-02

    Successive cold winters of severely low temperatures in recent years have had critical social and economic impacts on the mid-latitude continents in the Northern Hemisphere. Although these cold winters are thought to be partly driven by dramatic losses of Arctic sea ice, the mechanism that links sea ice loss to cold winters remains a subject of debate. Here, by conducting observational analyses and model experiments, we show how Arctic sea ice loss and cold winters in extra-polar regions are dynamically connected through the polar stratosphere. We find that decreased sea ice cover during early winter months (November-December), especially over the Barents-Kara seas, enhance the upward propagation of planetary-scale waves with wavenumbers of 1 and 2, subsequently weakening the stratospheric polar vortex in mid-winter (January- February). The weakened polar vortex preferentially induces a negative phase of Arctic Oscillation at the surface, resulting in low temperatures in mid-latitudes.

  6. Magnetic vortex crystal formation in the antidot complement of square artificial spin ice

    SciTech Connect (OSTI)

    Araujo, C. I. L. de Silva, R. C.; Ribeiro, I. R. B.; Nascimento, F. S.; Felix, J. F.; Ferreira, S. O.; Moura-Melo, W. A.; Pereira, A. R.; Mól, L. A. S.

    2014-03-03

    We have studied ferromagnetic nickel thin films patterned with square lattices of elongated antidots that are negative analogues of square artificial spin ice. Micromagnetic simulations and direct current magnetic moment measurements reveal in-plane anisotropy of the magnetic hysteresis loops, and the formation of a dense array of magnetic vortices with random polarization and chirality. These multiply-connected antidot arrays could be superior to lattices of disconnected nanodisks for investigations of vortex switching by applied electric current.

  7. Creation and pinning of vortex-antivortex pairs 

    E-Print Network [OSTI]

    Kim, Sangbum; Hu, Chia-Ren; Andrews, Malcolm J.

    2006-01-01

    in a superconducting thin film, due to the magnetic field of a vertical magnetic dipole above the film, and two antidot pins inside the film. For film thickness =0.1 xi, kappa=2, and no pins, we find the film carries two V-AV pairs at steady state...

  8. Comment on “General rotating quantum vortex filaments in the low-temperature Svistunov model of the local induction approximation” [Phys. Fluids 26, 065105 (2014)

    SciTech Connect (OSTI)

    Hietala, Niklas Hänninen, Risto

    2014-11-15

    Van Gorder considers a formulation of the local induction approximation, which allows the vortex to move in the direction of the reference axis [“General rotating quantum vortex filaments in the low-temperature Svistunov model of the local induction approximation,” Phys. Fluids 26, 065105 (2014)]. However, in his analytical and numerical study he does not use it. A mistake in the torsion of a helical vortex is also corrected.

  9. Vortices within vortices: hierarchical nature of vortex tubes in turbulence

    E-Print Network [OSTI]

    Bürger, Kai; Westermann, Rüdiger; Werner, Suzanne; Lalescu, Cristian C; Szalay, Alexander; Meneveau, Charles; Eyink, Gregory L

    2012-01-01

    The JHU turbulence database [1] can be used with a state of the art visualisation tool [2] to generate high quality fluid dynamics videos. In this work we investigate the classical idea that smaller structures in turbulent flows, while engaged in their own internal dynamics, are advected by the larger structures. They are not advected undistorted, however. We see instead that the small scale structures are sheared and twisted by the larger scales. This illuminates the basic mechanisms of the turbulent cascade.

  10. A vortex tube is a device of a simple structure with no moving parts that can be used to separate a compressed gas into a hot stream and a cold stream. Many studies have been

    E-Print Network [OSTI]

    A vortex tube is a device of a simple structure with no moving parts that can be used to separate of the energy separation in the vortex tube. Recent rapid development in computational fluid dynamics is providing a powerful tool to investigate the complex flow in the vortex tube. However various issues

  11. Molding the flow of light on the nanoscale: from vortex nanogears to phase-operated plasmonic machinery

    E-Print Network [OSTI]

    Boriskina, Svetlana V; 10.1039/C1NR11406A

    2011-01-01

    Efficient delivery of light into nanoscale volumes by converting free photons into localized charge-density oscillations (surface plasmons) enables technological innovation in various fields from biosensing to photovoltaics and quantum computing. Conventional plasmonic nanostructures are designed as nanoscale analogs of radioantennas and waveguides. Here, we discuss an alternative approach for plasmonic nanocircuit engineering that is based on molding the optical powerflow through 'vortex nanogears' around a landscape of local phase singularities 'pinned' to plasmonic nanostructures. We show that coupling of several vortex nanogears into transmission-like structures results in dramatic optical effects, which can be explained by invoking a hydrodynamic analogy of the 'photon fluid'. The new concept of vortex nanogear transmissions (VNTs) provides new design principles for the development of complex multi-functional phase-operated photonics machinery and, therefore, generates unique opportunities for light gene...

  12. Molding the flow of light on the nanoscale: from vortex nanogears to phase-operated plasmonic machinery

    E-Print Network [OSTI]

    Svetlana V. Boriskina; Bjoern M. Reinhard

    2011-12-07

    Efficient delivery of light into nanoscale volumes by converting free photons into localized charge-density oscillations (surface plasmons) enables technological innovation in various fields from biosensing to photovoltaics and quantum computing. Conventional plasmonic nanostructures are designed as nanoscale analogs of radioantennas and waveguides. Here, we discuss an alternative approach for plasmonic nanocircuit engineering that is based on molding the optical powerflow through 'vortex nanogears' around a landscape of local phase singularities 'pinned' to plasmonic nanostructures. We show that coupling of several vortex nanogears into transmission-like structures results in dramatic optical effects, which can be explained by invoking a hydrodynamic analogy of the 'photon fluid'. The new concept of vortex nanogear transmissions (VNTs) provides new design principles for the development of complex multi-functional phase-operated photonics machinery and, therefore, generates unique opportunities for light generation, harvesting and processing on the nanoscale.

  13. Scattering of electromagnetic waves by vortex density structures associated with interchange instability: Analytical and large scale plasma simulation results

    SciTech Connect (OSTI)

    Sotnikov, V.; Kim, T.; Lundberg, J.; Paraschiv, I.; Mehlhorn, T. A.

    2014-05-15

    The presence of plasma turbulence can strongly influence propagation properties of electromagnetic signals used for surveillance and communication. In particular, we are interested in the generation of low frequency plasma density irregularities in the form of coherent vortex structures. Interchange or flute type density irregularities in magnetized plasma are associated with Rayleigh-Taylor type instability. These types of density irregularities play an important role in refraction and scattering of high frequency electromagnetic signals propagating in the earth ionosphere, in high energy density physics, and in many other applications. We will discuss scattering of high frequency electromagnetic waves on low frequency density irregularities due to the presence of vortex density structures associated with interchange instability. We will also present particle-in-cell simulation results of electromagnetic scattering on vortex type density structures using the large scale plasma code LSP and compare them with analytical results.

  14. Meissner Effect and Vortex Dynamics in Quark Stars -- A Model for Soft Gamma-Ray Repeaters

    E-Print Network [OSTI]

    R. Ouyed; O. Elgaroy; H. Dahle; P. Keranen

    2004-03-24

    We present a new model for soft gamma-ray repeaters based on a quark star born with temperatures above the critical value (T_c) for the onset of the colour-flavor locked superconductivity. The quark star then quickly cools below T_c, expelling a fraction of the surface magnetic field via the Meissner effect. We show that if a small fraction (\\leq 10%) of the surface magnetic field (10^{14} - 10^{15} {\\rm G}) is expelled, it quickly decays via magnetic reconnection and heats up the quark star surface to temperatures > 10^9 {\\rm K}. Created (e^{+},e^{-}) pairs annihilate into gamma rays emitted in a giant burst (the first burst in our model), with a luminosity of \\sim 10^{45} {\\rm ergs} {\\rm s}^{-1}. Subsequent bursts result from the restructuring of the surface magnetic field following the formation and relaxation of a vortex lattice which confines the internal magnetic field. During this phase, energy is sporadically released as a consequence of magnetic reconnection events in the entangled surface magnetic field as it evolves into a smooth, more stable, configuration. The star eventually enters a quiescent phase in which energy is continuously supplied by vortex annihilation at the surface. As the star spins down, the outermost vortex lines will be pushed to the surface where they annihilate and release their confined magnetic field. We show that the corresponding luminosity is L_v \\sim 10^{36} {\\rm ergs} {\\rm s}^{-1} for a typical soft gamma-ray repeater spinning with a period of 8 {\\rm s} and a surface magnetic field not exceeding 10^{15} {\\rm G}. Our model can be applied to any situation where a T>T_{\\rm c} quark star is generated. We discuss the connection between anomalous X-ray pulsars and soft gamma-ray repeaters in the context of our model.

  15. Ultrasound scattering and the study of vortex correlations in disordered flows

    E-Print Network [OSTI]

    Denis Boyer; Fernando Lund

    1999-12-14

    In an idealized way, some turbulent flows can be pictured by assemblies of many vortices characterized by a set of particle distribution functions. Ultrasound provide an useful, nonintrusive, tool to study the spatial structure of vorticity in flows. This is analogous to the use of elastic neutron scattering to determine liquid structure. We express the dispersion relation, as well as the scattering cross section, of sound waves propagating in a ``liquid'' of identical vortices as a function of vortex pair correlation functions. In two dimensions, formal analogies with ionic liquids are pointed out.

  16. Extraordinary optical transmission and vortex excitation by periodic arrays of Fresnel zone plates

    E-Print Network [OSTI]

    Roszkiewicz, A

    2013-01-01

    Extraordinary optical transmission and good focusing properties of a two-dimensional scattering structure is presented. The structure is made of Fresnel zone plates periodically arranged along two orthogonal directions. Each plate consists of two ring-shaped waveguides supporting modes that match the symmetry of a circularly polarized incident plane wave. High field concentration at the focal plane is obtained with short transverse and long longitudinal foci diameters. Optical vortex excitation in a paraxial region of the transmitted field is also observed and analysed in terms of cross-polarisation coupling. The structure presented may appear useful in visualization, trapping and precise manipulations of nanoparticles.

  17. Antiferromagnetic transitions of osmium-containing rare earth double perovskites Ba{sub 2}LnOsO{sub 6} (Ln=rare earths)

    SciTech Connect (OSTI)

    Hinatsu, Yukio Doi, Yoshihiro; Wakeshima, Makoto

    2013-10-15

    The perovskite-type compounds containing both rare earth and osmium Ba{sub 2}LnOsO{sub 6} (Ln=Pr, Nd, Sm–Lu) have been prepared. Powder X-ray diffraction measurements and Rietveld analysis show that Ln{sup 3+} and Os{sup 5+} ions are structurally ordered at the M site of the perovskite BaMO{sub 3}. Magnetic susceptibility and specific heat measurements show that an antiferromagnetic ordering of Os{sup 5+} ions has been observed for Ba{sub 2}LnOsO{sub 6} (Ln=Pr, Nd, Sm, Eu, Gd, Lu) at 65–71 K. Magnetic ordering of Ln{sup 3+} moments occurs when the temperature is furthermore decreased. - Graphical abstract: The perovskite-type compounds containing both rare earth and osmium Ba{sub 2}LnOsO{sub 6} (Ln=Pr, Nd, Sm–Lu) have been prepared. An antiferromagnetic ordering of Os{sup 5+} ions has been observed for Ba{sub 2}LnOsO{sub 6} (Ln=Pr, Nd, Sm, Eu, Gd, Lu) at 65–71 K. Measurements and analysis of the specific heat for Ba{sub 2}PrOsO{sub 6} show that magnetic ordering of the Pr{sup 3+} moments should have occurred at ?20 K. Display Omitted.

  18. Antiferromagnetic, metal-insulator, and superconducting phase transitions in underdoped cuprates: Slave-fermion t-J model in the hopping expansion

    E-Print Network [OSTI]

    Akihiro Shimizu; Koji Aoki; Kazuhiko Sakakibara; Ikuo Ichinose; Tetsuo Matsui

    2010-07-24

    In the present paper, we study a system of doped antiferromagnet in three dimensions at finite temperatures by using the t-J model, a canonical model of strongly-correlated electrons. We employ the slave-fermion representation of electrons in which an electron is described as a composite of a charged spinless holon and a chargeless spinon. We introduce two kinds of U(1) gauge fields on links as auxiliary fields, one describing resonating valence bonds of antiferromagnetic nearest-neighbor spin pairs and the other for nearest-neighbor hopping amplitudes of holons and spinons in the ferromagnetic channel. In order to perform numerical study of the system, we integrate out the fermionic holon field by using the hopping expansion in powers of the hopping amplitude, which is legitimate for the region in and near the insulating phase. The resultant effective model is described in terms of bosonic spinons and the two U(1) gauge fields, and a collective field for hole pairs. We study this model by means of Monte-Carlo simulations, calculating the specific heat, spin correlation functions, and instanton densities. We obtain a phase diagram in the hole concentration-temperature plane, which is in good agreement with that observed recently for clean and homogeneous underdoped samples.

  19. Antiferromagnetic Kondo lattice in the layered compound CePd1–xBi? and comparison to the superconductor LaPd1–xBi?

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Han, Fei; Wan, Xiangang; Phelan, Daniel; Stoumpos, Constantinos C.; Sturza, Mihai; Malliakas, Christos D.; Li, Qing'an; Han, Tian-Heng; Zhao, Qingbiao; Chung, Duck Young; et al

    2015-07-13

    The layered compound CePd1–xBi? with the tetragonal ZrCuSi?-type structure was obtained from excess Bi flux. Magnetic susceptibility data of CePd1–xBi? show an antiferromagnetic ordering below 6 K and are anisotropic along the c axis and the ab plane. The anisotropy is attributed to crystal-electric-field (CEF) effects and a CEF model which is able to describe the susceptibility data is given. An enhanced Sommerfeld coefficient ? of 0.191 J mol Ce?¹ K?² obtained from specific-heat measurement suggests a moderate Kondo effect in CePd1–xBi?. Other than the antiferromagnetic peak at 6 K, the resistivity curve shows a shoulderlike behavior around 75 Kmore »which could be attributed to the interplay between Kondo and CEF effects. Magnetoresistance and Hall-effect measurements suggest that the interplay reconstructs the Fermi-surface topology of CePd1–xBi? around 75 K. Electronic structure calculations reveal that the Pd vacancies are important to the magnetic structure and enhance the CEF effects which quench the orbital moment of Ce at low temperatures.« less

  20. Critical current density and mechanism of vortex pinning in KxFe2-ySe? doped with S

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Lei, Hechang; Petrovic, C.

    2011-08-01

    We report the critical current density Jc in KxFe2-ySe2-zSz crystals. The Jc can be enhanced significantly with optimal S doping (z=0.99). For K0.70(7)Fe1.55(7)Se1.01(2)S0.99(2), the weak fishtail effect is found for H II c. The normalized vortex pinning forces follow the scaling law with a maximum position at 0.41 of the reduced magnetic field. These results demonstrate that the small size normal point defects dominate the vortex pinning mechanism.

  1. Origin State Destination State

    Gasoline and Diesel Fuel Update (EIA)

    rates for coal, state to state, STB data Origin State Destination State 2001 2002 2003 2004 2005 2006 2007 2008 2009 2001-2009 2008-2009 Alabama Alabama W W W W W W W W W W W...

  2. Venturi/vortex scrubber technology for controlling/recycling chromium electroplating emissions. Final report

    SciTech Connect (OSTI)

    Hay, K.J.; Qi, S.; Holden, B.; Helgeson, N.; Fraser, M.E.

    1999-03-01

    Chromium electroplating is an essential DOD process. Chromium has a combination of qualities that are very difficult to substitute, however, the process itself is inefficient, resulting in the production of byproduct gases that rise and create a mist of chromic acid (strongly regulated as an air pollutant) above the plating tank. Venturi/Vortex Scrubber Technology (VVST) was designed to control chromium electroplating emissions by collecting the gas bubbles before they burst at the solution`s surface. This project demonstrated the Venturi/Vortex Scrubber Technology at the Marine Corps Logistics Base (MCLB) in Albany, GA. This study concluded that the PLRS was able to reduce the flow rate of the current conventional ventilation system at the one tank chromium electroplating facility at MCLB Albany by 63 percent. If new ventilation and control equipment were to be installed at MCLB Albany, this system would offer a 25 percent reduction in capital costs and a 48 percent reduction in annual costs, representing 36 percent in life-cycle cost savings. This study also presented a strong case for the use of Spark-Induced Breakdown Spectroscopy for monitoring real-time chromium emissions above a chromium electroplating tank.

  3. MAP, MAC, and Vortex-rings Configurations in the Weinberg-Salam Model

    E-Print Network [OSTI]

    Rosy Teh; Ban-Loong Ng; Khai-Ming Wong

    2015-03-20

    We report on the presence of new axially symmetric monopoles, antimonopoles and vortex-rings solutions of the SU(2)$\\times$U(1) Weinberg-Salam model of electromagnetic and weak interactions. When the $\\phi$-winding number $n=1$, and 2, the configurations are monopole-antimonopole pair (MAP) and monopole-antimonopole chain (MAC) with poles of alternating sign magnetic charge arranged along the $z$-axis. Vortex-rings start to appear from the MAP and MAC configurations when the winding number $n=3$. The MAP configurations possess zero net magnetic charge whereas the MAC configurations possess net magnetic charge of $4\\pi n/e$. In the MAP configurations, the monopole-antimonopole pair is bounded by the ${\\cal Z}^0$ field flux string and there is an electromagnetic current loop encircling it. The monopole and antimonopole possess magnetic charges $\\pm\\frac{4\\pi n}{e}\\sin^2\\theta_W$ respectively. In the MAC configurations there is no string connecting the monopole and the adjacent antimonopole and they possess magnetic charges $\\pm\\frac{4\\pi n}{e}$ respectively. The MAC configurations possess infinite total energy and zero magnetic dipole moment whereas the MAP configurations which are actually sphalerons possess finite total energy and magnetic dipole moment. The configurations were investigated for varying values of Higgs self-coupling constant $0\\leq \\lambda\\leq 40$ at Weinberg angle $\\theta_W=\\frac{\\pi}{4}$.

  4. Direct femtosecond laser ablation of copper with an optical vortex beam

    SciTech Connect (OSTI)

    Anoop, K. K.; Rubano, A.; Marrucci, L.; Bruzzese, R.; Amoruso, S., E-mail: amoruso@na.infn.it [Dipartimento di Fisica, Università di Napoli Federico II, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Napoli (Italy); CNR-SPIN, UOS Napoli, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Napoli (Italy); Fittipaldi, R.; Vecchione, A. [CNR-SPIN, UOS Salerno, Via Giovanni Paolo II 132, I-84084 Fisciano (Italy); Wang, X.; Paparo, D. [CNR-SPIN, UOS Napoli, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Napoli (Italy)

    2014-09-21

    Laser surface structuring of copper is induced by laser ablation with a femtosecond optical vortex beam generated via spin-to-orbital conversion of the angular momentum of light by using a q-plate. The variation of the produced surface structures is studied as a function of the number of pulses, N, and laser fluence, F. After the first laser pulse (N=1), the irradiated surface presents an annular region characterized by a corrugated morphology made by a rather complex network of nanometer-scale ridges, wrinkles, pores, and cavities. Increasing the number of pulses (21000) and a deep crater is formed. The nanostructure variation with the laser fluence, F, also evidences an interesting dependence, with a coarsening of the structure morphology as F increases. Our experimental findings demonstrate that direct femtosecond laser ablation with optical vortex beams produces interesting patterns not achievable by the more standard beams with a Gaussian intensity profile. They also suggest that appropriate tuning of the experimental conditions (F, N) can allow generating micro- and/or nano-structured surface for any specific application.

  5. Ground state study of the thin ferromagnetic nano-islands for artificial spin ice arrays

    SciTech Connect (OSTI)

    Vieira Júnior, D. S.; Leonel, S. A. Dias, R. A. Toscano, D. Coura, P. Z. Sato, F.

    2014-09-07

    In this work, we used numerical simulations to study the magnetic ground state of the thin elongated (elliptical) ferromagnetic nano-islands made of Permalloy. In these systems, the effects of demagnetization of dipolar source generate a strong magnetic anisotropy due to particle shape, defining two fundamental magnetic ground state configurations—vortex or type C. To describe the system, we considered a model Hamiltonian in which the magnetic moments interact through exchange and dipolar potentials. We studied the competition between the vortex states and aligned states—type C—as a function of the shape of each elliptical nano-islands and constructed a phase diagram vortex—type C state. Our results show that it is possible to obtain the elongated nano-islands in the C-state with aspect ratios less than 2, which is interesting from the technological point of view because it will be possible to use smaller islands in spin ice arrays. Generally, the experimental spin ice arrangements are made with quite elongated particles with aspect ratio approximately 3 to ensure the C-state.

  6. Scattering and Bound State Green's Functions on a Plane via so(2,1) Lie Algebra

    E-Print Network [OSTI]

    P. F. Borges; H. Boschi-Filho; A. N. Vaidya

    2006-10-17

    We calculate the Green's functions for the particle-vortex system, for two anyons on a plane with and without a harmonic regulator and in a uniform magnetic field. These Green's functions which describe scattering or bound states (depending on the specific potential in each case) are obtained exactly using an algebraic method related to the SO(2,1) Lie group. From these Green's functions we obtain the corresponding wave functions and for the bound states we also find the energy spectra.

  7. 1242 JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 20, NO. 8, AUGUST 2002 Performances of the Data Vortex Switch Architecture

    E-Print Network [OSTI]

    Bergman, Keren

    the efficient scalability of the architecture under uniform and random traffic conditions while maintaining high1242 JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 20, NO. 8, AUGUST 2002 Performances of the Data Vortex Switch Architecture Under Nonuniform and Bursty Traffic Qimin Yang, Member, IEEE, and Keren Bergman

  8. First-Order Transition in the Magnetic Vortex Matter in Superconducting MgB2 Tuned by Disorder

    E-Print Network [OSTI]

    Boyer, Edmond

    First-Order Transition in the Magnetic Vortex Matter in Superconducting MgB2 Tuned by Disorder T such as Wigner crystals, charge density waves, magnetic bubble arrays, or vortices in type-II superconductors posi- tional correlations. Vortices in superconductors rapidly became the system of choice

  9. Vortex Nucleation in a Stirred Bose-Einstein Condensate Dissipation and turbulence in superfluid flow often involves the creation and

    E-Print Network [OSTI]

    . This observation confirms the role of discrete surface modes in vortex formation. However, when we used a tightly. The nucleation process has been a subject of much theoretical interest [1]. Experiments with Bose. These resonances were close to the frequencies of excitation for surface modes of different multipolarity

  10. Nonequilibrium dynamic phases and plastic flow of driven vortex lattices in superconductors with periodic arrays of pinning sites

    E-Print Network [OSTI]

    Nori, Franco

    of lattices as a driving force is increased. For superconducting systems, experimental work in neutron conductivity. By monitoring the moving vortex lattice, we show that these features coincide with pronounced by elastic theories. Different system parameters produce other phases, including an ordered channel flow

  11. Effect of time-dependent piston velocity program on vortex ring formation in a piston/cylinder arrangement

    E-Print Network [OSTI]

    Dabiri, John O.

    Graduate Aeronautical Laboratories and Bioengineering, California Institute of Technology, Pasadena velocity fixed. It turned out that the pinch-off was always observed to occur at a stroke ratio L time scale for the pinch-off process formation number was tested by generating vortex rings

  12. To appear in the ACM SIGGRAPH conference proceedings Filament-based smoke with vortex shedding and variational reconnection

    E-Print Network [OSTI]

    Weissmann, Steffen

    To appear in the ACM SIGGRAPH conference proceedings Filament-based smoke with vortex shedding filaments is highly attractive for the creation of special effects because it gives artists full control filaments over time. Because filaments offer a very compact description of fluid flow, real time

  13. arXiv:nlin.SI/0612065v129Dec2006 FINITE-GAP SOLUTIONS OF THE VORTEX FILAMENT EQUATION

    E-Print Network [OSTI]

    Calini, Annalisa

    arXiv:nlin.SI/0612065v129Dec2006 FINITE-GAP SOLUTIONS OF THE VORTEX FILAMENT EQUATION: ISOPERIODIC filament equation in a neighborhood of multiply covered circles. We construct these solutions by means that matches the deformation data with the knot type of the resulting filament. 1. Introduction In this sequel

  14. Stationary Vortex Loops Induced by Filament Interaction and Local Pinning in a Chemical Reaction-Diffusion System

    E-Print Network [OSTI]

    Steinbock, Oliver

    Stationary Vortex Loops Induced by Filament Interaction and Local Pinning in a Chemical Reaction rings are three-dimensional excitation waves rotating around one-dimensional filament loops but curved filaments. The absence of filament motion can be explained by repulsive interaction

  15. Paper No. 2004-JSC-396 Srivilairit Identification and Analysis of Vortex-Induced Vibrations of a Drilling Riser

    E-Print Network [OSTI]

    Manuel, Lance

    of a deepwater drilling riser. We examine such data from the monitoring of riser accelerations and vortex a deepwater drilling riser. The site has a water depth of 1,000 meters. These riser acceleration data consist of a Drilling Riser using Empirical and Spectral Procedures Tanapat Srivilairit and Lance Manuel Department

  16. Strong vortex core pinning and Barkhausen-free magnetization response in thin Permalloy disks induced by implantation of 1 × 10{sup 4} Ga{sup +} ions

    SciTech Connect (OSTI)

    Fani Sani, F., E-mail: fanisani@ualberta.ca, E-mail: mark.freeman@ualberta.ca; Losby, J. E.; Diao, Z.; Parsons, L. C.; Burgess, J. A. J.; Hiebert, W. K.; Freeman, M. R., E-mail: fanisani@ualberta.ca, E-mail: mark.freeman@ualberta.ca [Department of Physics, University of Alberta, Edmonton, Alberta T6G 2G7 (Canada); National Institute for Nanotechnology (NINT), Edmonton, Alberta T6G 2M9 (Canada); Vick, D. [National Institute for Nanotechnology (NINT), Edmonton, Alberta T6G 2M9 (Canada)

    2014-05-07

    Artificial vortex core pinning sites are induced in thin Permalloy disks by point exposure to as few as 10?000 ions from a focused Ga{sup +} beam. These pinning sites yield a first-order change in the magnetization response of the disk. A single site can keep the vortex core pinned over an applied field range comparable to the vortex annihilation field of the unaltered disk. Several widely separated sites can work together to keep the core pinned in one place, while the Barkhausen effect is eliminated from the magnetization curve over a range approaching the saturation moment of the disk.

  17. Development of venturi/vortex scrubber technology for controlling chromium electroplating hazardous air emissions. Final report

    SciTech Connect (OSTI)

    Hay, K.J.; Qi, S.; Northrup, J.I.; Heck, S.R.

    1998-07-01

    Chromium has a combination of qualities that give chromium electroplating an important role in coating military hardware and armament. However, chromium electroplating and chromium anodizing operations create hazardous air pollutants in the form of hexavalent chromium. Conventional technologies for controlling this pollutant are expensive, noisy, and use a lot of energy and water. Consequently, an air pollution problem is turned into a water pollution problem that also requires treatment. There is a need for an economical control option that pollutes less than conventional technologies. This project developed control technologies to effectively and economically control hazardous air emissions from Army chromium electroplating and anodizing operations, primarily focusing on the development of the Venturi/Vortex Scrubber technology (VVST).

  18. Non-Diffracting Electron Vortex Beams Balancing Their Electron-Electron Interactions

    E-Print Network [OSTI]

    Maor Mutzafi; Ido Kaminer; Gal Harari; Mordechai Segev

    2015-10-10

    By introducing concepts of beam shaping into quantum mechanics, we show how interference effects of the quantum wavefunction describing multiple electrons can exactly balance the repulsion among the electrons. With proper shaping of the fermionic wavefunction, we propose non-diffracting quantum wavepackets of multiple electrons that can also carry orbital angular momentum, in the form of multi-electron non-diffracting vortex beams. The wavefunction is designed to compensate for both the repulsion between electrons and for the diffraction-broadening. This wavefunction shaping facilitates the use of electron beams of higher current in numerous applications, thereby improving the signal-to-noise-ratio in electron microscopy and related systems without compromising on the spatial resolution. Our scheme potentially applies for any beams of charged particles, such as protons, muons and ion beams.

  19. Vortex Zero Modes, Large Flux Limit and Ambjørn-Nielsen-Olesen Magnetic Instabilities

    E-Print Network [OSTI]

    Stefano Bolognesi; Chandrasekhar Chatterjee; Sven Bjarke Gudnason; Kenichi Konishi

    2014-09-23

    In the large flux limit vortices become flux tubes with almost constant magnetic field in the interior region. This occurs in the case of non-Abelian vortices as well, and the study of such configurations allows us to reveal a close relationship between vortex zero modes and the gyromagnetic instabilities of vector bosons in a strong background magnetic field discovered by Nielsen, Olesen and Ambj{\\o}rn. The BPS vortices are exactly at the onset of this instability, and the dimension of their moduli space is precisely reproduced in this way. We present a unifying picture in which, through the study of the linear spectrum of scalars, fermions and W bosons in the magnetic field background, the expected number of translational, orientational, fermionic as well as semilocal zero modes is correctly reproduced in all cases.

  20. Vortex precession frequency and its amplitude-dependent shift in cylindrical nanomagnets

    SciTech Connect (OSTI)

    Metlov, Konstantin L.

    2013-12-14

    Frequency of free magnetic vortex precession in circular soft ferromagnetic nano-cylinders (magnetic dots) of various sizes is an important parameter, used in design of spintronic devices (such as spin-torque microwave nano-oscillators) and characterization of magnetic nanostructures. Here, using a recently developed collective-variable approach to non-linear dynamics of magnetic textures in planar nano-magnets, this frequency and its amplitude-dependent shift are computed analytically and plotted for the full range of cylinder geometries. The frequency shift is positive in large planar dots, but becomes negative in smaller and more elongated ones. At certain dot dimensions, a zero frequency shift is realized, which can be important for enhancing frequency stability of magnetic nano-oscillators.

  1. Optimization of vortex pinning by nanoparticles using simulations of time-dependent Ginzburg-Landau model

    E-Print Network [OSTI]

    A. E. Koshelev; I. A. Sadovskyy; C. L. Phillips; A. Glatz

    2015-10-01

    Introducing nanoparticles into superconducting materials has emerged as an efficient route to enhance their current-carrying capability. We address the problem of optimizing vortex pinning landscape for randomly distributed metallic spherical inclusions using large-scale numerical simulations of time-dependent Ginzburg-Landau equations. We found the size and density of particles for which the highest critical current is realized in a fixed magnetic field. For each particle size and magnetic field, the critical current reaches a maximum value at a certain particle density, which typically corresponds to 15-23% of the total volume being replaced by nonsuperconducting material. For fixed diameter, this optimal particle density increases with the magnetic field. Moreover, we found that the optimal particle diameter slowly decreases with the magnetic field from 4.5 to 2.5 coherence lengths at a given temperature. This result shows that pinning landscapes have to be designed for specific applications taking into account relevant magnetic field scales.

  2. Optimized focal and pupil plane masks for vortex coronagraphs on telescopes with obstructed apertures

    E-Print Network [OSTI]

    Ruane, Garreth J; Huby, Elsa; Mawet, Dimitri; Delacroix, Christian; Carlomagno, Brunella; Piron, Pierre; Swartzlander, Grover A

    2015-01-01

    We present methods for optimizing pupil and focal plane optical elements that improve the performance of vortex coronagraphs on telescopes with obstructed or segmented apertures. Phase-only and complex masks are designed for the entrance pupil, focal plane, and the plane of the Lyot stop. Optimal masks are obtained using both analytical and numerical methods. The latter makes use of an iterative error reduction algorithm to calculate "correcting" optics that mitigate unwanted diffraction from aperture obstructions. We analyze the achieved performance in terms of starlight suppression, contrast, off-axis image quality, and chromatic dependence. Manufacturing considerations and sensitivity to aberrations are also discussed. This work provides a path to joint optimization of multiple coronagraph planes to maximize sensitivity to exoplanets and other faint companions.

  3. Vortex Lattice Studies in CeCoIn? with H?c

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Das, P.; White, J. S.; Holmes, A. T.; Gerber, S.; Forgan, E. M.; Bianchi, A. D.; Kenzelmann, M.; Zolliker, M.; Gavilano, J. L.; Bauer, E. D.; et al

    2012-02-01

    We present small angle neutron scattering studies of the vortex lattice (VL) in CeCoIn? with magnetic fields applied parallel (H) to the antinodal [100] and nodal [110] directions. For H II 100], a single VL orientation is observed, while a 90° reorientation transition is found for H II [110]. For both field orientations and VL configurations we find a distorted hexagonal VL with an anisotropy, ?=2.0±0.05. The VL form factor shows strong Pauli paramagnetic effects similar to what have previously been reported for H II [001]. At high fields, above which the upper critical field (Hc2) becomes a first-order transition,more »an increased disordering of the VL is observed.« less

  4. Ultra-fast magnetic vortex core reversal by a local field pulse

    SciTech Connect (OSTI)

    Rückriem, R.; Albrecht, M., E-mail: manfred.albrecht@physik.uni-augsburg.de [Institute of Physics, Chemnitz University of Technology, 09107 Chemnitz (Germany); Schrefl, T. [St. Pölten University of Applied Science, 3100 St. Pölten (Austria)

    2014-02-03

    Magnetic vortex core reversal of a 20-nm-thick permalloy disk with a diameter of 100?nm was studied by micromagnetic simulations. By applying a global out-of-plane magnetic field pulse, it turned out that the final core polarity is very sensitive to pulse width and amplitude, which makes it hard to control. The reason for this phenomenon is the excitation of radial spin waves, which dominate the reversal process. The excitation of spin waves can be strongly suppressed by applying a local field pulse within a small area at the core center. With this approach, ultra-short reversal times of about 15 ps were achieved, which are ten times faster compared to a global pulse.

  5. Bounds on topological Abelian string-vortex and string-cigar from information-entropic measure

    E-Print Network [OSTI]

    Correa, R A C; Almeida, C A S; da Rocha, Roldao

    2016-01-01

    In this work we obtain bounds on topological Abelian string-vortex in six dimensions using a new measure of configurational complexity known as configurational entropy. In this way, the information-theoretical measure of six dimensional braneworlds scenarios are capable to probe situations where the parameters responsible for the thickness are arbitrary. The so-called Configurational Entropy (CE) selects the best value of the parameter in the model. This is accomplished by minimizing the CE, namely, by selecting the most appropriate parameters in the model that correspond to the most organized system, based upon Shannon information theory. This information-theoretical measure of complexity provides a complementary perspective to situations where strictly energy-based arguments are inconclusive. We show that the higher the energy the higher the configurational entropy, what shows an important correlation between the energy of the a localized field configuration and its associated entropic measure.

  6. Analytical description of high-aperture STED resolution with 0-2$\\pi$ vortex phase modulation

    E-Print Network [OSTI]

    Xie, Hao; Jin, Dayong; Xi, Peng

    2013-01-01

    Stimulated emission depletion (STED) can achieve optical super-resolution, with the optical diffraction limit broken by the suppression on the periphery of the fluorescent focal spot. Previously, it is generally experimentally accepted that there exists an inverse square root relationship with the STED power and the resolution, yet without strict analytical description. In this paper, we have analytically verified the relationship between the STED power and the achievable resolution from vector optical theory for the widely used 0-2$\\pi$ vortex phase modulation. Electromagnetic fields of the focal region of a high numerical aperture objective are calculated and approximated into polynomials, and analytical expression of resolution as a function of the STED intensity has been derived. As a result, the resolution can be estimated directly from the measurement of the saturation power of the dye and the STED power applied.

  7. Method for the detection of a magnetic field utilizing a magnetic vortex

    DOE Patents [OSTI]

    Novosad, Valentyn (Chicago, IL); Buchanan, Kristen (Batavia, IL)

    2010-04-13

    The determination of the strength of an in-plane magnetic field utilizing one or more magnetically-soft, ferromagnetic member, having a shape, size and material whereas a single magnetic vortex is formed at remanence in each ferromagnetic member. The preferred shape is a thin circle, or dot. Multiple ferromagnetic members can also be stacked on-top of each other and separated by a non-magnetic spacer. The resulting sensor is hysteresis free. The sensor's sensitivity, and magnetic saturation characteristics may be easily tuned by simply altering the material, size, shape, or a combination thereof to match the desired sensitivity and saturation characteristics. The sensor is self-resetting at remanence and therefore does not require any pinning techniques.

  8. Control of magnetic, nonmagnetic, and superconducting states in annealed Ca(Fe1–xCox)?As?

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Ran, S.; Bud'ko, S. L.; Straszheim, W. E.; Soh, J.; Kim, M. G.; Kreyssig, A.; Goldman, A. I.; Canfield, P. C.

    2012-06-22

    We have grown single-crystal samples of Co substituted CaFe?As? using an FeAs flux and systematically studied the effects of annealing/quenching temperature on the physical properties of these samples. Whereas the as-grown samples (quenched from 960°C) all enter the collapsed tetragonal phase upon cooling, annealing/quenching temperatures between 350 and 800°C can be used to tune the system to low-temperature antiferromagnetic/orthorhomic or superconducting states as well. The progression of the transition temperature versus annealing/quenching temperature (T-Tanneal) phase diagrams with increasing Co concentration shows that, by substituting Co, the antiferromagnetic/orthorhombic and the collapsed tetragonal phase lines are separated and bulk superconductivity is revealed.more »We established a 3D phase diagram with Co concentration and annealing/quenching temperature as two independent control parameters. At ambient pressure, for modest x and Tanneal values, the Ca(Fe??xCox)?As? system offers ready access to the salient low-temperature states associated with Fe-based superconductors: antiferromagnetic/orthorhombic, superconducting, and nonmagnetic/collapsed tetragonal.« less

  9. Magnetic ground state of semiconducting transition metal trichalcogenide monolayers

    SciTech Connect (OSTI)

    Sivadas, Mr. Nikhil [Carnegie Mellon University (CMU); Daniels, Matthew W. [Carnegie Mellon University (CMU); Swendsen, Robert H. [Carnegie Mellon University (CMU); Okamoto, Satoshi [ORNL; Xiao, Di [Carnegie Mellon University (CMU)

    2015-01-01

    Layered transition-metal trichalcogenides with the chemical formula ABX3 have attracted recent interest as potential candidates for two-dimensional magnets. Using first-principles calculations within density functional theory, we investigate the magnetic ground states of monolayers of Mn- and Cr-based semiconducting trichalcogenides.We show that the second and third nearest-neighbor exchange interactions (J2 and J3) between magnetic ions, which have been largely overlooked in previous theoretical studies, are crucial in determining the magnetic ground state. Specifically, we find that monolayer CrSiTe3 is an antiferromagnet with a zigzag spin texture due to significant contribution from J3, whereas CrGeTe3 is a ferromagnet with a Curie temperature of 106 K. Monolayers of Mn compounds (MnPS3 and MnPSe3) always show antiferromagnetic N eel order. We identify the physical origin of various exchange interactions, and demonstrate that strain can be an effective knob for tuning the magnetic properties. Possible magnetic ordering in the bulk is also discussed. Our study suggests that ABX3 can be a promising platform to explore two-dimensional magnetic phenomena.

  10. Interaction of a Shock with a Longitudinal Vortex 1 Gordon Erlebacher 2 , M.Y. Hussaini 3 and ChiWang Shu 4

    E-Print Network [OSTI]

    Erlebacher, Gordon

    vortex shed from a canard of a supersonic fighter plane intersects the shock that lies over the wing are appropriate), resulting in destabilizing forces on the airplane (D'elery et al: 1984). Thus, a theoretical

  11. Vortex Diode Analysis and Testing for Fluoride Salt-Cooled High-Temperature Reactors

    SciTech Connect (OSTI)

    Yoder Jr, Graydon L [ORNL; Elkassabgi, Yousri M. [Texas A& M University, Kingsville; De Leon, Gerardo I. [Texas A& M University, Kingsville; Fetterly, Caitlin N. [Texas A& M University, Kingsville; Ramos, Jorge A. [Texas A& M University, Kingsville; Cunningham, Richard Burns [University of Tennessee, Knoxville (UTK)

    2012-02-01

    Fluidic diodes are presently being considered for use in several fluoride salt-cooled high-temperature reactor designs. A fluidic diode is a passive device that acts as a leaky check valve. These devices are installed in emergency heat removal systems that are designed to passively remove reactor decay heat using natural circulation. The direct reactor auxiliary cooling system (DRACS) uses DRACS salt-to-salt heat exchangers (DHXs) that operate in a path parallel to the core flow. Because of this geometry, under normal operating conditions some flow bypasses the core and flows through the DHX. A flow diode, operating in reverse direction, is-used to minimize this flow when the primary coolant pumps are in operation, while allowing forward flow through the DHX under natural circulation conditions. The DRACSs reject the core decay heat to the environment under loss-of-flow accident conditions and as such are a reactor safety feature. Fluidic diodes have not previously been used in an operating reactor system, and therefore their characteristics must be quantified to ensure successful operation. This report parametrically examines multiple design parameters of a vortex-type fluidic diode to determine the size of diode needed to reject a particular amount of decay heat. Additional calculations were performed to size a scaled diode that could be tested in the Oak Ridge National Laboratory Liquid Salt Flow Loop. These parametric studies have shown that a 152.4 mm diode could be used as a test article in that facility. A design for this diode is developed, and changes to the loop that will be necessary to test the diode are discussed. Initial testing of a scaled flow diode has been carried out in a water loop. The 150 mm diode design discussed above was modified to improve performance, and the final design tested was a 171.45 mm diameter vortex diode. The results of this testing indicate that diodicities of about 20 can be obtained for diodes of this size. Experimental results show similar trends as the computational fluid dynamics (CFD) results presented in this report; however, some differences exist that will need to be assessed in future studies. The results of this testing will be used to improve the diode design to be tested in the liquid salt loop system.

  12. Flame-vortex interaction driven combustion dynamics in a backward-facing step combustor

    SciTech Connect (OSTI)

    Altay, H. Murat; Speth, Raymond L.; Hudgins, Duane E.; Ghoniem, Ahmed F.

    2009-05-15

    The combustion dynamics of propane-hydrogen mixtures are investigated in an atmospheric pressure, lean, premixed backward-facing step combustor. We systematically vary the equivalence ratio, inlet temperature and fuel composition to determine the stability map of the combustor. Simultaneous pressure, velocity, heat release rate and equivalence ratio measurements and high-speed video from the experiments are used to identify and characterize several distinct operating modes. When fuel is injected far upstream from the step, the equivalence ratio entering the flame is temporally and spatially uniform, and the combustion dynamics are governed only by flame-vortex interactions. Four distinct dynamic regimes are observed depending on the operating parameters. At high but lean equivalence ratios, the flame is unstable and oscillates strongly as it is wrapped around the large unsteady wake vortex. At intermediate equivalence ratios, weakly oscillating quasi-stable flames are observed. Near the lean blowout limit, long stable flames extending from the corner of the step are formed. At atmospheric inlet temperature, the unstable mode resonates at the 1/4 wavemode of the combustor. As the inlet temperature is increased, the 5/4 wavemode of the combustor is excited at high but lean equivalence ratios, forming the high-frequency unstable flames. Higher hydrogen concentration in the fuel and higher inlet temperatures reduce the equivalence ratios at which the transitions between regimes are observed. We plot combustion dynamics maps or the response curves, that is the overall sound pressure level as a function of the equivalence ratio, for different operating conditions. We demonstrate that numerical results of strained premixed flames can be used to collapse the response curves describing the transitions among the dynamic modes onto a function of the heat release rate parameter alone, rather than a function dependent on the equivalence ratio, inlet temperature and fuel composition separately. We formulate a theory for predicting the critical values of the heat release parameter at which quasi-stable to unstable and unstable to high-frequency unstable modes take place. (author)

  13. Effects of coexisting spin disorder and antiferromagnetism on the magnetic behavior of nanostructured (Fe{sub 79}Mn{sub 21}){sub 1?x}Cu{sub x} alloys

    SciTech Connect (OSTI)

    Mizrahi, M. E-mail: cabrera@fisica.unlp.edu.ar; Cabrera, A. F. E-mail: cabrera@fisica.unlp.edu.ar; Desimoni, J.; Stewart, S. J.

    2014-06-07

    We report a magnetic study on nanostructured (Fe{sub 79}Mn{sub 21}){sub 1?x}Cu{sub x} (0.00???x???0.30) alloys using static magnetic measurements. The alloys are mainly composed by an antiferromagnetic fcc phase and a disordered region that displays a spin-glass-like behavior. The interplay between the antiferromagnetic and magnetically disordered phases establishes an exchange anisotropy that gives rise to a loop shift at temperatures below the freezing temperature of moments belonging to the disordered region. The loop shift is more noticeable as the Cu content increases, which also enhances the spin-glass-like features. Further, in the x?=?0.30 alloy the alignment imposed by applied magnetic fields higher than 4 kOe prevail over the configuration determined by the frustration mechanism that characterizes the spin glass-like phase.

  14. Topological relics of symmetry breaking: Winding numbers and scaling tilts from random vortex-antivortex pairs

    E-Print Network [OSTI]

    Wojciech H. Zurek

    2014-10-01

    I show that random distributions of vortex-antivortex pairs (rather than of individual vortices) lead to scaling of typical winding numbers W trapped inside a loop of circumference C with the square root of C when the expected winding numbers are large. Such scaling is consistent with the Kibble-Zurek mechanism (KZM). By contrast, distribution of individual vortices with randomly assigned topological charges would result in the dispersion of W scaling with the square root of the area inside C. Scaling of the dispersion of W and of the probability of detection of non-zero W with C can be also studied for loops so small that non-zero windings are rare. In this case I show a doubling of the scaling of dispersion with C when compared to the scaling of dispersion in the large W regime. Moreover, probability of trapping of a non-zero W becomes, in this case, proportional to the area subtended by C (hence, to the square of circumference). This quadruples, as compared with large winding numbers regime, the exponent in the power law dependence of the frequency of trapping of W=+1 or W=-1 on C. Such change of the power law exponent by a FACTOR OF FOUR implies quadrupling of the scaling of the frequency of winding number trapping with the quench rate, and is of key importance for experimental tests of KZM.

  15. Temporal evolution characteristics of an annular-mode gliding arc discharge in a vortex flow

    SciTech Connect (OSTI)

    Zhao, Tian-Liang; Liu, Jing-Lin; Li, Xiao-Song; Liu, Jin-Bao; Song, Yuan-Hong; Xu, Yong; Zhu, Ai-Min

    2014-05-15

    An annular-mode gliding arc discharge powered by a 50?Hz alternating current (ac) supply was studied in a vortex flow of dry and humid air. Its temporal evolution characteristics were investigated by electrical measurement, temporally resolved imaging, and temporally resolved optical emission spectroscopic measurements. Three discharge stages of arc-ignition, arc-gliding, and arc-extinction were clearly observed in each half-cycle of the discharge. During the arc-gliding stage, the intensity of light emission from the arc root at the cathode was remarkably higher than that at other areas. The spectral intensity of N{sub 2}(C{sup 3}?{sub u}?B{sup 3}?{sub g}) during the arc-ignition stage was much higher than that during the arc-gliding stage, which was contrary to the temporal evolutions of spectral intensities for N{sub 2}{sup +}(B{sup 2}?{sub u}{sup +}?X{sup 2}?{sub g}{sup +}) and OH(A{sup 2}?{sup +}?X{sup 2}?{sub i}). Temporally resolved vibrational and rotational temperatures of N{sub 2} were also presented and decreased with increasing the water vapor content.

  16. Mixing antiferromagnets to tune NiFe-[IrMn/FeMn] interfacial spin-glasses, grains thermal stability, and related exchange bias properties

    SciTech Connect (OSTI)

    Akmaldinov, K.; Ducruet, C.; Portemont, C.; Joumard, I.; Prejbeanu, I. L.; Dieny, B.; Baltz, V.

    2014-05-07

    Spintronics devices and in particular thermally assisted magnetic random access memories require a wide range of ferromagnetic/antiferromagnetic (F/AF) exchange bias (EB) properties and subsequently of AF materials to fulfil diverse functionality requirements for the reference and storage. For the reference layer, large EB energies and high blocking temperature (T{sub B}) are required. In contrast, for the storage layer, mostly moderate T{sub B} are needed. One of the present issues is to find a storage layer with properties intermediate between those of IrMn and FeMn and in particular: (i) with a T{sub B} larger than FeMn for better stability at rest-T but lower than IrMn to reduce power consumption at write-T and (ii) with improved magnetic interfacial quality, i.e., with reduced interfacial glassy character for lower properties dispersions. To address this issue, the EB properties of F/AF based stacks were studied for various mixed [IrMn/FeMn] AFs. In addition to EB loop shifts, the F/AF magnetic interfacial qualities and the AF grains thermal stability are probed via measurements of the low- and high-temperature contributions to the T{sub B} distributions, respectively. A tuning of the above three parameters is observed when evolving from IrMn to FeMn via [IrMn/FeMn] repetitions.

  17. Coexistence of antiferromagnetic and ferromagnetic spin correlations in SrCo2As2 revealed by Co59 and As75 NMR

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wiecki, P.; Ogloblichev, V.; Pandey, Abhishek; Johnston, D. C.; Furukawa, Y.

    2015-06-15

    In nonsuperconducting, metallic paramagnetic SrCo2As2, inelastic neutron scattering measurements have revealed strong stripe-type q=(?,0) antiferromagnetic (AFM) spin correlations. Using nuclear magnetic resonance (NMR) measurements on 59Co and 75Asnuclei, we demonstrate that stronger ferromagnetic (FM) spin correlations coexist in SrCo2As2. Our NMR data are consistent with density functional theory (DFT) calculations which show enhancements at both q=(?,0) and the in-plane FM q=0 wave vectors in static magnetic susceptibility ?(q). We suggest that the strong FM fluctuations prevent superconductivity in SrCo2As2, despite the presence of stripe-type AFM fluctuations. Since DFT calculations have consistently revealed similar enhancements of the ?(q) at both q=(?,0)more »and q=0 in the iron-based superconductors and parent compounds, our observation of FM correlations in SrCo2As2 calls for detailed studies of FM correlations in the iron-based superconductors.« less

  18. Crystal structure and antiferromagnetic ordering of quasi-2D [Cu(HF{sub 2})(pyz){sub 2}]TaF{sub 6} (pyz = pyrazine).

    SciTech Connect (OSTI)

    Manson, J. L.; Schlueter, J. A.; McDonald, R. D.; Singleton, J.; Materials Science Division; Eastern Washington Univ.; LANL

    2010-04-01

    The crystal structure of the title compound was determined by X-ray diffraction at 90 and 295 K. Copper(II) ions are coordinated to four bridging pyz ligands to form square layers in the ab-plane. Bridging HF{sub 2}{sup -} ligands join the layers together along the c-axis to afford a tetragonal, three-dimensional (3D) framework that contains Taf{sub 6}{sup -} anions in every cavity. At 295 K, the pyz rings lie exactly perpendicular to the layers and cooling to 90 K induces a canting of those rings. Magnetically, the compound exhibits 2D antiferromagnetic correlations within the 2D layers with an exchange interaction of -13.1(1) K. Weak interlayer interactions, as mediated by Cu-F-H-F-Cu, leads to long-range magnetic order below 4.2 K. Pulsed-field magnetization data at 0.5 K show a concave curvature with increasing B and reveal a saturation magnetization at 35.4 T.

  19. Magnetic structure and domain conversion of the quasi-2D frustrated antiferromagnet CuCrO{sub 2} probed by NMR

    SciTech Connect (OSTI)

    Sakhratov, Yu. A. [National High Magnetic Field Laboratory (United States); Svistov, L. E., E-mail: svistov@kapitza.ras.ru [Russian Academy Sciences, Kapitza Institute for Physical Problems (Russian Federation); Kuhns, P. L.; Zhou, H. D.; Reyes, A. P. [National High Magnetic Field Laboratory (United States)

    2014-11-15

    We have carried out {sup 63,65}Cu NMR spectra measurements in a magnetic field up to about 15.5 T on a single crystal of the multiferroic triangular-lattice antiferromagnet CuCrO{sub 2}. The measurements were performed for perpendicular and parallel orientations of the magnetic field with respect to the c axis of the crystal, and the detailed angle dependence of the spectra on the magnetic field direction in the ab plane was studied. The shape of the spectra can be well described in the model of spiral spin structure proposed by recent neutron diffraction experiments. When the field is rotated perpendicular to the crystal c axis, we observed, directly for the first time, a remarkable reorientation of the spin plane simultaneous with rotation of the incommensurate wavevector, by quantitatively deducing the conversion of the energetically less favorable domain to a more favorable one. At high enough fields parallel to the c axis, the data are consistent with either a field-induced commensurate spiral magnetic structure or an incommensurate spiral magnetic structure with a disorder in the c direction, suggesting that high fields may have influence on interplanar ordering.

  20. Twofold enhancement of the hidden-order/large-moment antiferromagnetic phase boundary in the URu2-xFexSi? system

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kanchanavatee, N.; Janoschek, M.; Baumbach, R. E.; Hamlin, J. J.; Zocco, D. A.; Huang, K.; Maple, M. B.

    2011-12-16

    Electrical resistivity, specific heat, and magnetization measurements on URu2-xFexSi? reveal a twofold enhancement of the “hidden-order” (HO)/large-moment antiferromagnetic (LMAFM) phase boundary T?(x). The T?(Pch) curve, obtained by converting x to “chemical pressure” Pch, is strikingly similar to the T?(P) curve, where P is applied pressure, for URu?Si? both exhibit a “kink” at 1.5 GPa and a maximum at ~7 GPa. This similarity suggests that the HO-LMAFM transition at 1.5 GPa in URu?Si? occurs at x ? 0.2 (Pch?1.5 GPa) in URu2-xFexSi?. URu2-xFexSi? provides an opportunity for studying the HO and LMAFM phases with methods that probe the electronic structure [e.g.,more »scanning tunneling microscopy (STM), angle-resolved photoemission spectroscopy (ARPES), and point-contact spectroscopy (PCS)] but cannot be used under pressure.« less

  1. Simulating local measurements on a quantum many body system with stochastic matrix product states

    E-Print Network [OSTI]

    Søren Gammelmark; Klaus Mølmer

    2009-11-25

    We demonstrate how to simulate both discrete and continuous stochastic evolution of a quantum many body system subject to measurements using matrix product states. A particular, but generally applicable, measurement model is analyzed and a simple representation in terms of matrix product operators is found. The technique is exemplified by numerical simulations of the anti-ferromagnetic Heisenberg spin-chain model subject to various instances of the measurement model. In particular we focus on local measurements with small support and non-local measurements which induces long range correlations.

  2. Investigation of vortex generators for augmentation of wind turbine power performance

    SciTech Connect (OSTI)

    Griffin, D.A. [Lynette (R.) and Associates, Seattle, WA (United States)

    1996-12-01

    This study focuses on the use of vortex generators (VGs) for performance augmentation of the stall-regulated AWT-26 wind turbine. The goal was to design a VG array which would increase annual energy production (AEP) by increasing power output at moderate wind speeds, without adversely affecting the loads or stall-regulation performance of the turbine. Wind tunnel experiments were conducted at the University of Washington to evaluate the effect of VGs on the AWT-26 blade, which is lofted from National Renewable Energy Laboratory (NREL) S-series airfoils. Based on wind-tunnel results and analysis, a VG array was designed and then tested on the AWT-26 prototype, designated P1. Performance and loads data were measured for P1, both with and without VGs installed. the turbine performance with VGs met most of the design requirements; power output was increased at moderate wind speeds with a negligible effect on peak power. However, VG drag penalties caused a loss in power output for low wind speeds, such that performance with VGs resulted in a net decrease in AEP for sites having annual average wind speeds up to 8.5 m/s. While the present work did not lead to improved AEP for the AWT-2 turbine, it does provide insight into performance augmentation of wind turbines with VGs. The safe design of a VG array for a stall-regulated turbine has been demonstrated, and several issues involving optimal performance with VGs have been identified and addressed. 15 refs., 34 figs., 10 tabs.

  3. Smooth double critical state theory for type-II superconductors

    E-Print Network [OSTI]

    H. S. Ruiz; A. Bad\\'\\ia-Majós

    2010-05-30

    Several aspects of the general theory for the critical states of a vortex lattice and the magnetic flux dynamics in type-II superconductors are examined by a direct variational optimisation method and widespread physical principles. Our method allows to unify a number of conventional models describing the complex vortex configurations in the critical state regime. Special attention is given to the discussion of the relation between the flux-line cutting mechanism and the depinning threshold limitation. This is done by using a smooth double critical state concept which incorporates the so-called isotropic, elliptical, T and CT models as well-defined limits of our general treatment. Starting from different initial configurations for a superconducting slab in a 3D magnetic field, we show that the predictions of the theory range from the collapse to zero of transverse magnetic moments in the isotropic model, to nearly force free configurations in which paramagnetic values can arbitrarily increase with the applied field for magnetically anisotropic current voltage laws. Noteworthily, the differences between the several model predictions are minimal for the low applied field regime.

  4. Comment on “Motion of a helical vortex filament in superfluid {sup 4}He under the extrinsic form of the local induction approximation” [Phys. Fluids 25, 085101 (2013)

    SciTech Connect (OSTI)

    Hietala, Niklas Hänninen, Risto

    2014-01-15

    We comment on the paper by Van Gorder [“Motion of a helical vortex filament in superfluid {sup 4}He under the extrinsic form of the local induction approximation,” Phys. Fluids 25, 085101 (2013)]. We point out that the flow of the normal fluid component parallel to the vortex will often lead into the Donnelly–Glaberson instability, which will cause the amplification of the Kelvin wave. We explain why the comparison to local nonlinear equation is unreasonable, and remark that neglecting the motion in the x-direction is not reasonable for a Kelvin wave with an arbitrary wavelength and amplitude. The correct equations in the general case are also derived.

  5. From the Newton's laws to motions of the fluid and superfluid vacuum: vortex tubes, rings, and others

    E-Print Network [OSTI]

    Sbitnev, Valeriy I

    2014-01-01

    Owing to three conditions (namely: (a) the velocity is represented by sum of irrotational and solenoidal components; (b) the fluid is barotropic; (c) a bath with the fluid undergoes vertical vibrations) the Navier-Stokes equation admits reduction to the modified Hamilton-Jacobi equation. The modification term is the Bohmian(quantum) potential. This reduction opens possibility to define a complex-valued function, named the wave function, which is a solution of the Schr\\"{o}dinger equation. The solenoidal component being added to the momentum operator poses itself as a vector potential by analogy with the magnetic vector potential. The vector potential is represented by the solenoidal velocity multiplied by mass of the fluid element. Vortex tubes, rings, and balls along with the wave function guiding these objects are solutions of this equation. Motion of the vortex balls along the Bohmian trajectories gives a model of droplets moving on the fluid surface. A peculiar fluid is the superfluid physical vacuum. It ...

  6. Competing magnetic ground states in non-superconducting Ba(Fe1-xCrx)2As2

    SciTech Connect (OSTI)

    Marty, Karol J [ORNL; Christianson, Andrew D [ORNL; Wang, Cuihuan [ORNL; Matsuda, Masaaki [ORNL; Cao, Huibo [ORNL; VanBebber, L. H. [University of Tennessee, Knoxville (UTK); Zaretsky, Jerel L. [Ames Laboratory and Iowa State University; Singh, David J [ORNL; Sefat, A. S. [Oak Ridge National Laboratory (ORNL); Lumsden, Mark D [ORNL

    2011-01-01

    We present neutron diffraction measurements on single-crystal samples of nonsuperconducting Ba(Fe{sub 1-x}Cr{sub x}){sub 2}As{sub 2} as a function of Cr doping for 0 x 0.47. The average spin-density-wave moment is independent of concentration for x 0.2 and decreases rapidly for x 0.3. For concentrations in excess of 30% chromium, we find a new competing magnetic phase consistent with G-type antiferromagnetism which rapidly becomes the dominant magnetic ground state. Strong magnetism is observed for all concentrations measured, naturally explaining the absence of superconductivity in the Cr-doped materials.

  7. Highly efficient electron vortex beams generated by nanofabricated phase holograms Vincenzo Grillo, Gian Carlo Gazzadi, Ebrahim Karimi, Erfan Mafakheri, Robert W. Boyd, and Stefano Frabboni

    E-Print Network [OSTI]

    Boyd, Robert W.

    Highly efficient electron vortex beams generated by nanofabricated phase holograms Vincenzo Grillo membranes using electron-beam lithography J. Vac. Sci. Technol. B 31, 06F402 (2013); 10.1063/1.4810917 Ion and electron beam nanofabrication of the which-way double-slit experiment in a transmission

  8. Coreless vortex formation in a spinor Bose-Einstein condensate Topological defects vary between superfluid systems described by scalar and vector

    E-Print Network [OSTI]

    Coreless vortex formation in a spinor Bose-Einstein condensate Topological defects vary between-polarized condensates, line defects such as vortices have cores where the density of condensed particles is necessarily zero to keep the order parameter single-valued. However, in condensates with an internal, spin degree

  9. Topological vortex formation in a Bose-Einstein condensate Following the theoretical suggestion [1], we have demonstrated a new method to

    E-Print Network [OSTI]

    Topological vortex formation in a Bose-Einstein condensate Following the theoretical suggestion [1], we have demonstrated a new method to create vortices in Bose-Einstein condensates. Vortices were imprinted into the condensate wavefunction using topological phases. Sodium condensates held in an Ioffe

  10. Suppressible pinning of Abrikosov vortices : effects of magnetic vortex arrays on thin superconducting films

    E-Print Network [OSTI]

    Smith, Kevin Daniel

    2008-01-01

    penetration through the superconductive film as it relatesThus, to sustain superconductivity throughout the materialthe mixed state, type-II superconductors have characteristic

  11. Modification of vortex dynamics and transport properties of transitional axisymmetric jets using zero-net-mass-flux actuation

    SciTech Connect (OSTI)

    Önder, Asim; Meyers, Johan

    2014-07-15

    We study the near field of a zero-net-mass-flux (ZNMF) actuated round jet using direct numerical simulations. The Reynolds number of the jet Re{sub D} = 2000 and three ZNMF actuators are used, evenly distributed over a circle, and directed towards the main jet. The actuators are triggered in phase, and have a relatively low momentum coefficient of C{sub ?} = 0.0049 each. We study four different control frequencies with Strouhal numbers ranging from St{sub D} = 0.165 to St{sub D} = 1.32; next to that, also two uncontrolled baseline cases are included in the study. We find that this type of ZNMF actuation leads to strong deformations of the near-field jet region that are very similar to those observed for non-circular jets. At the end of the jet's potential core (x/D = 5), the jet-column cross section is deformed into a hexagram-like geometry that results from strong modifications of the vortex structures. Two mechanisms lead to these modifications, i.e., (i) self-deformation of the jet's primary vortex rings started by distortions in their azimuthal curvature by the actuation, and (ii) production of side jets by the development and subsequent detachment of secondary streamwise vortex pairs. Further downstream (x/D = 10), the jet transforms into a triangular pattern, as the sharp corner regions of the hexagram entrain fluid and spread. We further investigate the global characteristics of the actuated jets. In particular when using the jet preferred frequency, i.e., St{sub D} = 0.33, parameters such as entrainment, centerline decay rate, and mean turbulent kinetic energy are significantly increased. Furthermore, high frequency actuation, i.e., St{sub D} = 1.32, is found to suppress the mechanisms leading to large scale structure growth and turbulent kinetic energy production. The simulations further include a passive scalar equation, and passive scalar mixing is also quantified and visualized.

  12. FRUSTRATED ANTIFERROMAGNETS EASY AXIS ANISOTROPY

    E-Print Network [OSTI]

    of Fundamental Research, Mumbai, India for the degree of Doctor of Philosophy in Physics By Arnab Sen Department of Theoretical Physics Tata Institute of Fundamental Research Mumbai - 400 005, India June 2009 #12 Kedar Damle, at the Tata Institute of Fundamental Research, Mumbai. (Arnab Sen) In my capacity

  13. Investigations of the Dimerized Antiferromagnetic

    E-Print Network [OSTI]

    Petta, Jason

    ;Theoretical Spin Wave Energy Spectra #12;Theoretical One-magnon Energy Spectra #12;Conclusions · More going temperature superconductivity · Many future technological applications ­ Need to understand physics first

  14. Theoretical susceptibilities of linear antiferromagnets 

    E-Print Network [OSTI]

    McSwain, Sulane

    1968-01-01

    '"SECRETIONAL SUSOE1'TIBILITJ 1". S OE LIFEAH MVI1'1 BBOI~i!'GNETS A Thesis Fy Sulenc NcSwain Snbmitt, e:I to +he Grad&sate Coils~a of the Texas A&-i'i Uniq~er si ty 1n par'I lal fnlfi ) ir. ;ant, of the reqnl re@eats for the d". ;-z ee...) QI'Iomber ) IIay, '. 9SS ACK170'vs 7 DEMENT I w i. el i t o exp r e s s my aZ&pr e c i at i on t o: Dr. P. J. Smentowsri for serving as chairman of my committee and for his advising and. directing in matters concerned. witn this research; Dr. R...

  15. The influence of current collectors on Tayler instability and electro-vortex flows in liquid metal batteries

    E-Print Network [OSTI]

    Weber, N; Priede, J; Stefani, F; Weier, T

    2014-01-01

    The Tayler instability is a kink-type flow instability which occurs when the electrical current through a conducting fluid exceeds a certain critical value. Originally studied in the astrophysical context, the instability was recently shown to be also a limiting factor for the upward scalability of liquid metal batteries. In this paper, we continue our efforts to simulate this instability for liquid metals within the framework of an integro-differential equation approach. The original solver is enhanced by multi-domain support with Dirichlet-Neumann partitioning for the static boundaries. Particular focus is laid on the detailed influence of the axial electrical boundary conditions on the characteristic features of the Tayler instability, and, secondly, on the occurrence of electro-vortex flows and their relevance for liquid metal batteries.

  16. Negative specific heat for quasi-2D vortex structures in electron plasmas: an explicit, closed-form derivation

    E-Print Network [OSTI]

    T. D. Andersen; C. C. Lim

    2008-02-29

    Negative specific heat is a dramatic phenomenon where processes decrease in temperature when adding energy. It has been observed in gravo-thermal collapse of globular clusters. We now report finding this phenomenon in bundles of nearly parallel, periodic, single-sign generalized vortex filaments in the electron magnetohydrodynamic (EMH) model for the unbounded plane under strong magnetic confinement. We derive the specific heat using a steepest descent method and a mean field property. Our derivations show that as temperature increases, the overall size of the system increases exponentially and the energy drops. The implication of negative specific heat is a runaway reaction, resulting in a collapsing inner core surrounded by an expanding halo of filaments.

  17. Model for characterization of a vortex pair formed by shock passage over a light-gas inhomogeneity

    SciTech Connect (OSTI)

    Yang, J.; Kubota, T.; Zukoski, E.E.

    1994-01-01

    This work investigates the two-dimensional flow of a shock wave over a circular light-gas inhomogeneity in a channel with finite width. The pressure gradient from the shock wave interacts with the density gradient at the edge of the inhomogeneity to deposit vorticity around the perimeter, and the structure rolls up into a pair of counter-rotating vortices. The aim of this study is to develop an understanding of the scaling laws for the flow field produced by this interaction at times long after the passage of the shock across the inhomogeneity. Numerical simulations are performed for various initial conditions and the results are used to guide the development of relatively simple algebraic models that characterize the dynamics of the vortex pair, and that allow extrapolation of the numerical results to conditions more nearly of interest in practical situations. The models are not derived directly from the equations of motion but depend on these equations and on intuition guided by the numerical results. Agreement between simulations and models is generally good except for a vortex-spacing model which is less satisfactory. A practical application of this shock-induced vortical flow is rapid and efficient mixing of fuel and oxidizer in a SCRAMJET combustion chamber. One possible injector design uses the interaction of an oblique shock wave with a jet of light fuel to generate vorticity which stirs and mixes the two fluids and lifts the burning jet away from the combustor wall. Marble proposed an analogy between this three-dimensional steady flow and the two-dimensional unsteady problem of the present investigation. Comparison is made between closely corresponding three-dimensional steady and two-dimensional unsteady flows, and a mathematical description of Marble`s analogy is proposed. 17 refs.

  18. Ground state properties and high pressure behavior of plutonium dioxide: Systematic density functional calculations

    E-Print Network [OSTI]

    Zhang, Ping; Zhao, Xian-Geng

    2010-01-01

    Plutonium dioxide is of high technological importance in nuclear fuel cycle and is particularly crucial in long-term storage of Pu-based radioactive waste. Using first-principles density-functional theory, in this paper we systematically study the structural, electronic, mechanical, thermodynamic properties, and pressure induced structural transition of PuO$_{2}$. To properly describe the strong correlation in the Pu $5f$ electrons, the local density approximation$+U$ and the generalized gradient approximation$+U$ theoretical formalisms have been employed. We optimize the $U$ parameter in calculating the total energy, lattice parameters, and bulk modulus at the nonmagnetic, ferromagnetic, and antiferromagnetic configurations for both ground state fluorite structure and high pressure cotunnite structure. The best agreement with experiments is obtained by tuning the effective Hubbard parameter $U$ at around 4 eV within the LDA$+U$ approach. After carefully testing the validity of the ground state, we further in...

  19. A Minimal Model for Brownian Vortexes Bo Sun, David G. Grier, and Alexander Y. Grosberg

    E-Print Network [OSTI]

    Grier, David

    ]. The second distinguishes them from deterministic machines such as electric motors. The third requires is noise-driven machine that uses thermal fluctuations to extract a steady- state flow of work from of random thermal forcing. Such noise-driven machines have been studied intensively at least since Maxwell

  20. A Minimal Model for Brownian Vortexes Bo Sun, David G. Grier, and Alexander Y. Grosberg

    E-Print Network [OSTI]

    Grier, David

    ]. The second distinguishes them from deterministic machines such as electric motors. The third requires is noise­driven machine that uses thermal fluctuations to extract a steady­ state flow of work from of random thermal forcing. Such noise­driven machines have been studied intensively at least since Maxwell

  1. Entanglement spectra of the q-deformed Affleck-Kennedy-Lieb-Tasaki model and matrix product states

    E-Print Network [OSTI]

    Raul A. Santos; Francis N. C. Paraan; Vladimir E. Korepin; Andreas Klümper

    2012-05-14

    We exactly calculate the reduced density matrix of matrix product states (MPS). Our compact result enables one to perform analytic studies of entanglement in MPS. In particular, we consider the MPS ground states of two anisotropic spin chains. One is a q-deformed Affleck-Kennedy-Lieb-Tasaki (AKLT) model and the other is a general spin-1 quantum antiferromagnet with nearest-neighbor interactions. Our analysis shows how anisotropy affects entanglement on different continuous parameter manifolds. We also construct an effective boundary spin model that describes a block of spins in the ground state of the q-deformed AKLT Hamiltonian. The temperature of this effective model is given in terms of the deformation parameter q.

  2. Effects of Combustion-Induced Vortex Breakdown on Flashback Limits of Syngas-Fueled Gas Turbine Combustors

    SciTech Connect (OSTI)

    Ahsan Choudhuri

    2011-03-31

    Turbine combustors of advanced power systems have goals to achieve very low pollutants emissions, fuel variability, and fuel flexibility. Future generation gas turbine combustors should tolerate fuel compositions ranging from natural gas to a broad range of syngas without sacrificing operational advantages and low emission characteristics. Additionally, current designs of advanced turbine combustors use various degrees of swirl and lean premixing for stabilizing flames and controlling high temperature NOx formation zones. However, issues of fuel variability and NOx control through premixing also bring a number of concerns, especially combustor flashback and flame blowout. Flashback is a combustion condition at which the flame propagates upstream against the gas stream into the burner tube. Flashback is a critical issue for premixed combustor designs, because it not only causes serious hardware damages but also increases pollutant emissions. In swirl stabilized lean premixed turbine combustors onset of flashback may occur due to (i) boundary layer flame propagation (critical velocity gradient), (ii) turbulent flame propagation in core flow, (iii) combustion instabilities, and (iv) upstream flame propagation induced by combustion induced vortex breakdown (CIVB). Flashback due to first two foregoing mechanisms is a topic of classical interest and has been studied extensively. Generally, analytical theories and experimental determinations of laminar and turbulent burning velocities model these mechanisms with sufficient precision for design usages. However, the swirling flow complicates the flashback processes in premixed combustions and the first two mechanisms inadequately describe the flashback propensity of most practical combustor designs. The presence of hydrogen in syngas significantly increases the potential for flashback. Due to high laminar burning velocity and low lean flammability limit, hydrogen tends to shift the combustor operating conditions towards flashback regime. Even a small amount of hydrogen in a fuel blend triggers the onset of flashback by altering the kinetics and thermophysical characteristics of the mixture. Additionally, the presence of hydrogen in the fuel mixture modifies the response of the flame to the global effects of stretch and preferential diffusion. Despite its immense importance in fuel flexible combustor design, little is known about the magnitude of fuel effects on CIVB induced flashback mechanism. Hence, this project investigates the effects of syngas compositions on flashback resulting from combustion induced vortex breakdown. The project uses controlled experiments and parametric modeling to understand the velocity field and flame interaction leading to CIVB driven flashback.

  3. Vortex characterisation of frustration in the 2d Ising spin glass

    E-Print Network [OSTI]

    K. Langfeld; M. Quandt; W. Lutz; H. Reinhardt

    2010-12-16

    The frustrated Ising model on a two-dimensional lattice with open boundary conditions is revisited. A hidden Z2 gauge symmetry relates models with different frustrations which, however, share the same partition function. By means of a duality transformation, it is shown that the partition function only depends on the distribution of gauge invariant vortices on the lattice. We finally show that the exact ground state energy can be calculated in polynomial time using Edmonds' algorithm.

  4. Quantum paraelectric glass state in SrCu{sub 3}Ti{sub 4}O{sub 12}

    SciTech Connect (OSTI)

    Kumar, Jitender; Choudhary, Ram Janay; Awasthi, A. M., E-mail: amawasthi@csr.res.in [UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452001 (India)

    2014-06-30

    Magnetic and dielectric studies of SrCu{sub 3}Ti{sub 4}O{sub 12} carried out over 5–300?K confirm antiferromagnetic (AFM) ordering of Cu-spins at T{sub N}?=?23?K. Dielectric constant ?? measured across 1?Hz-1 MHz signifies quantum paraelectric character, Barrett-fittable almost down to T{sub N}. Competition of athermal fluctuations and the literature-reported magneto-phonon-softening near T{sub N} manifest a quantum paraelectric glass (QPG) state. Emergent AFM-field tunes the otherwise quantum ordering (at absolute-zero) of the dipoles to finite-temperature kinetic glass transition; spectral dispersion of dielectric constant was unambiguously manifested and characterized. Vogel-Fulcher glass-kinetics parameterization sets the almost relaxation-free QPG state in SrCu{sub 3}Ti{sub 4}O{sub 12} apart from an emergent scaling-class, to which typical ferroelectric relaxors belong.

  5. Improving Vortex Generators to Enhance the Performance of Air-Cooled Condensers in a Geothermal Power Plant

    SciTech Connect (OSTI)

    Manohar S. Sohal

    2005-09-01

    This report summarizes work at the Idaho National Laboratory to develop strategies to enhance air-side heat transfer in geothermal air-cooled condensers such that it should not significantly increase pressure drop and parasitic fan pumping power. The work was sponsored by the U.S. Department of Energy, NEDO (New Energy and Industrial Technology Development Organization) of Japan, Yokohama National University, and the Indian Institute of Technology, Kanpur, India. A combined experimental and numerical investigation was performed to investigate heat transfer enhancement techniques that may be applicable to largescale air-cooled condensers such as those used in geothermal power applications. A transient heat transfer visualization and measurement technique was employed in order to obtain detailed distributions of local heat transfer coefficients on model fin surfaces. Pressure drop measurements were obtained for a variety of tube and winglet configurations using a single-channel flow apparatus that included four tube rows in a staggered array. Heat transfer and pressure drop measurements were also acquired in a separate multiple-tube row apparatus in the Single Blow Test Facility. In addition, a numerical modeling technique was developed to predict local and average heat transfer for these low-Reynolds number flows, with and without winglets. Representative experimental and numerical results were obtained that reveal quantitative details of local finsurface heat transfer in the vicinity of a circular tube with a single delta winglet pair downstream of the cylinder. Heat transfer and pressure-drop results were obtained for flow Reynolds numbers based on channel height and mean flow velocity ranging from 700 to 6500. The winglets were of triangular (delta) shape with a 1:2 or 1:3 height/length aspect ratio and a height equal to 90% of the channel height. Overall mean fin-surface heat transfer results indicate a significant level of heat transfer enhancement (in terms of Colburn j-factor) associated with deployment of the winglets with circular as well as oval tubes. In general, toe-in (common flow up) type winglets appear to have better performance than the toe-out (common flow down) type winglets. Comparisons of heat transfer and pressure drop results for the elliptical tube versus a circular tube with and without winglets are provided. During the course of their independent research, all of the researchers have established that about 10 to 30% enhancement in Colburn j-factor is expected. However, actual increase in heat transfer rate from a heat exchanger employing finned tubes with winglets may be smaller, perhaps on the order of 2 to 5%. It is also concluded that for any specific application, more full-size experimentation is needed to optimize the winglet design for a specific heat exchanger application. If in place of a circular tube, an oval tube can be economically used in a bundle, it is expected that the pressure drop across the tube bundle with the application of vortex generators (winglets) will be similar to that in a conventional circular tube bundle. It is hoped that the results of this research will demonstrate the benefits of applying vortex generators (winglets) on the fins to improve the heat transfer from the air-side of the tube bundle.

  6. Turbulence-induced melting of a nonequilibrium vortex crystal in a forced thin fluid film

    E-Print Network [OSTI]

    Prasad Perlekar; Rahul Pandit

    2009-10-16

    To develop an understanding of recent experiments on the turbulence-induced melting of a periodic array of vortices in a thin fluid film, we perform a direct numerical simulation of the two-dimensional Navier-Stokes equations forced such that, at low Reynolds numbers, the steady state of the film is a square lattice of vortices. We find that, as we increase the Reynolds number, this lattice undergoes a series of nonequilibrium phase transitions, first to a crystal with a different reciprocal lattice and then to a sequence of crystals that oscillate in time. Initially the temporal oscillations are periodic; this periodic behaviour becomes more and more complicated, with increasing Reynolds number, until the film enters a spatially disordered nonequilibrium statistical steady that is turbulent. We study this sequence of transitions by using fluid-dynamics measures, such as the Okubo-Weiss parameter that distinguishes between vortical and extensional regions in the flow, ideas from nonlinear dynamics, e.g., \\Poincare maps, and theoretical methods that have been developed to study the melting of an equilibrium crystal or the freezing of a liquid and which lead to a natural set of order parameters for the crystalline phases and spatial autocorrelation functions that characterise short- and long-range order in the turbulent and crystalline phases, respectively.

  7. Magnetic States in Fe Nanoparticles Imaged by Off-axis Electron Holography Luise Theil Kuhn1*

    E-Print Network [OSTI]

    Dunin-Borkowski, Rafal E.

    a procedure that is described elsewhere [1]. In FIG. 1 (d), a magnetic vortex surrounds a flux tube that runs.e. their magnetic configurations may be vortex-like. The critical size for this transition from single domain to vortex behaviour is crucial for determining the net magnetic moments carried by magnetic nanoparticles, i

  8. A survey of ideal fluid propeller theories and a study of the effects of aerodynamic propeller loading on trailing vortex induced velocity and thrust 

    E-Print Network [OSTI]

    Kelley, Edward Madison

    1969-01-01

    A SURVEY OF IDEAL FLUID PRO~ THEORIES AND A STUIE OP THE EFFECTS OF AERODYNAMIC PRO~ LOADING ON TRAILING VORTEX INDUCED VELOCITY AND THRUST A Thesis EDWARD MADISON ~ Suhmitted to the Graduate College of Texas A&M University in Partial... VELOCITY AND THRUST A Thesis by EDWARD MADISON HELLEY Approsed as to sty1e and content 'by: Head of epartment i%. mbe August 1969 111 ABSTRACT A Survey of Ideal Fluid Propeller Theories and a Study of the Ei'fects of Aerodynamic Propeller...

  9. State Overview

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious Rank EERE:Financing Tool FitsProjectDataSecretaryDepartment7 Annual2InformationState Energy RevolvingState

  10. Shedding of Vortex Rings from an Oscillating Sphere in Superfluid He-4 below 0.5 K - The Origin of the Turbulent Drag Force

    E-Print Network [OSTI]

    Schoepe, W

    2013-01-01

    The onset of turbulent flow around an oscillating sphere is known to occur at a critical velocity vc ~ sqrt(kappa omega) where kappa is the circulation quantum and omega is the oscillation frequency. However, in a small interval of driving force amplitudes F (or corresponding velocity amplitudes of few percent above vc) the turbulent flow is found to be unstable. The flow pattern switches intermittently between potential flow and turbulence. The lifetimes of the turbulent phases have an exponential distribution and the mean lifetimes tau grow very rapidly with increasing driving force, namely as tau(F) ~ exp [(F/F1)^2]. In this work this experimental result is analyzed in more detail than before, in particular the force F1 is identified. As a result, the turbulent drag force F(v) ~ (v^2 - vc^2) can be ascribed quantitatively to the shedding of vortex rings having the size of the sphere. Moreover, we can infer the average number of vortex rings that are shed per half-period at any given velocity v on the turbu...

  11. Spatially evolving vortex-gas turbulent free shear layers: Part 1. Effect of velocity ratio, and upstream and downstream conditions on spread-rate

    E-Print Network [OSTI]

    Suryanarayanan, Saikishan

    2015-01-01

    The relevance of the vortex-gas model to the large scale dynamics of temporally evolving turbulent free shear layers in an inviscid incompressible fluid has recently been established by extensive numerical simulations (Suryanarayanan et al, Phys. Rev. E 89, 013009, 2014). Here, the effects of the velocity ratio across a spatially evolving 2D free shear layer are investigated by vortex-gas simulations, using a computational model based on Basu et al (1992, 1995), but with a crucial improvement that ensures conservation of global circulation. These are carried out for a range of values of the velocity ratio parameter $\\lambda= (U_1-U_2)/(U_1+U_2)$, where $U_1$ and $U_2$ ($< U_1$) are respective velocities across the layer. The simulations show that the conditions imposed at the beginning of the free shear layer and at the exit to the domain can affect the flow evolution in their respective neighborhoods, the latter being particularly strong as $\\lambda \\rightarrow 1$. In between the two neighborhoods is a re...

  12. Understanding and controlling complex states arising from magnetic frustration

    SciTech Connect (OSTI)

    Zapf, Vivien

    2012-06-01

    Much of our national security relies on capabilities made possible by magnetism, in particular the ability to compute and store huge bodies of information as well as to move things and sense the world. Most of these technologies exploit ferromagnetism, i.e. the global parallel alignment of magnetic spins as seen in a bar magnet. Recent advances in computing technologies, such as spintronics and MRAM, take advantage of antiferromagnetism where the magnetic spins alternate from one to the next. In certain crystal structures, however, the spins take on even more complex arrangements. These are often created by frustration, where the interactions between spins cannot be satisfied locally or globally within the material resulting in complex and often non-coplanar spin textures. Frustration also leads to the close proximity of many different magnetic states, which can be selected by small perturbations in parameters like magnetic fields, temperature and pressure. It is this tunability that makes frustrated systems fundamentally interesting and highly desirable for applications. We move beyond frustration in insulators to itinerant systems where the interaction between mobile electrons and the non-coplanar magnetic states lead to quantum magneto-electric amplification. Here a small external field is amplified by many orders of magnitude by non-coplanar frustrated states. This greatly enhances their sensitivity and opens broader fields for applications. Our objective is to pioneer a new direction for condensed matter science at the Laboratory as well as for international community by discovering, understanding and controlling states that emerge from the coupling of itinerant charges to frustrated spin textures.

  13. VOLUME 83, NUMBER 8 P H Y S I C A L R E V I E W L E T T E R S 23 AUGUST 1999 Flow Induced Organization and Memory of a Vortex Lattice

    E-Print Network [OSTI]

    Andrei, Eva Y.

    in response to a driving current in 2H-NbSe2 crystals. By using fast transport measurements we find exhibits a long-term memory: if the current is turned off the vortices freeze in place remembering) [15] and transport measurements [5], it is inversely proportional to the size of an ordered vortex

  14. Magnetization reversal assisted by half antivortex states in nanostructured circular cobalt disks

    SciTech Connect (OSTI)

    Lara, A.; Aliev, F. G.; Dobrovolskiy, O. V.; Prieto, J. L.; Huth, M.

    2014-11-03

    The half antivortex, a fundamental topological structure which determines magnetization reversal of submicron magnetic devices with domain walls, has been suggested also to play a crucial role in spin torque induced vortex core reversal in circular disks. Here, we report on magnetization reversal in circular disks with nanoholes through consecutive metastable states with half antivortices. In-plane anisotropic magnetoresistance and broadband susceptibility measurements accompanied by micromagnetic simulations reveal that cobalt (Co) disks with two and three linearly arranged nanoholes directed at 45° and 135° with respect to the external magnetic field show reproducible step-like changes in the anisotropic magnetoresistance and magnetic permeability due to transitions between different intermediate states mediated by vortices and half antivortices confined to the dot nanoholes and edges, respectively. Our findings are relevant for the development of multi-hole based spintronic and magnetic memory devices.

  15. STATE of the STATE Survey State of the State SurveyState of the State Survey

    E-Print Network [OSTI]

    Riley, Shawn J.

    8White 8.3 9.8 Black 5.7 12.4 Democrat 2.4 15.4 Republican 12.2 2.8 Detroit 3.9 9.2 Southeast Michigan (excluding Detroit) 9.8 10.8 #12;STATE of the STATE Survey Percent of Michigan Residents Who Rate.3 Black 33.5 12.8 53.7 Democrat 14.6 15.8 69.7 Republican 34.1 22.3 43.6 Detroit 32 4 14 0 53 7Detroit 32

  16. Synthesis and characterization of a new layered organic-inorganic hybrid nickel(II) 1,4:5,8-naphthalenediimide bis-phosphonate, exhibiting canted antiferromagnetism, with T{sub c}{approx}21 K

    SciTech Connect (OSTI)

    Bauer, Elvira M. Bellitto, Carlo; Gomez Garcia, Carlos J. Righini, Guido

    2008-05-15

    A new Ni(II) layered hybrid organic-inorganic compound of formula Ni{sub 2}[(NDI-BP)(H{sub 2}O){sub 2}].2H{sub 2}O has been prepared in very mild conditions from N,N'-bis(2-phosphonoethyl)napthalene-1,4:5,8-tetracarboximide (NDI-BP ligand) and NiCl{sub 2}. The X-ray powder structure characterization of the title compound suggests a pillared layered organic-inorganic hybrid structure. The distance between the organic and inorganic layers has been found to be 17.8 A. The inorganic layers consist of corner sharing [NiO{sub 5}(H{sub 2}O)] octahedra and they are pillared by the diphosphonate groups. DC and AC magnetic measurements as a function of temperature and field indicate the presence of 2D antiferromagnetic exchange interactions between the nearest-neighbor Ni(II) ions below 100 K. A long-range magnetic ordering at T{sub c}{approx}21 K has been established and is attributed to the presence of spin canting. AC magnetic measurements as a function of temperature at different frequencies confirm the occurrence of the magnetic ordering temperature at T=21 K and the presence of a slight structural disorder in the title compound. - Graphical abstract: A new layered hybrid organic-inorganic Ni(II) N,N'-bis(2-phosphonoethyl)-naphthalene 1,4:5,8 tetracarboxydiimide complex has been synthesized and characterized. Magnetic measurements as a function of temperature and at different fields show that the compound is magnetically ordered below T{sub c}{approx}21 K.

  17. Annular vortex combustor

    DOE Patents [OSTI]

    Nieh, Sen (Burtonsville, MD); Fu, Tim T. (Camarillo, CA)

    1992-01-01

    An apparatus for burning coal water fuel, dry ultrafine coal, pulverized l and other liquid and gaseous fuels including a vertically extending outer wall and an inner, vertically extending cylinder located concentrically within the outer wall, the annnular space between the outer wall and the inner cylinder defining a combustion chamber and the all space within the inner cylinder defining an exhaust chamber. Fuel and atomizing air are injected tangentially near the bottom of the combustion chamber and secondary air is introduced at selected points along the length of the combustion chamber. Combustion occurs along the spiral flow path in the combustion chamber and the combined effects of centrifugal, gravitational and aerodynamic forces cause particles of masses or sizes greater than the threshold to be trapped in a stratified manner until completely burned out. Remaining ash particles are then small enough to be entrained by the flue gas and exit the system via the exhaust chamber in the opposite direction.

  18. State Overview

    Broader source: Energy.gov (indexed) [DOE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of Natural GasAdjustmentsShirleyEnergyThe U.S. Department ofEnergy(Department orAn exampleThe StartupagendaitsState million

  19. State Overview

    Broader source: Energy.gov (indexed) [DOE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of Natural GasAdjustmentsShirleyEnergyThe U.S. Department ofEnergy(Department orAn exampleThe StartupagendaitsState

  20. State Overview

    Broader source: Energy.gov (indexed) [DOE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of Natural GasAdjustmentsShirleyEnergyThe U.S. Department ofEnergy(Department orAn exampleThe StartupagendaitsState83

  1. State Overview

    Broader source: Energy.gov (indexed) [DOE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of Natural GasAdjustmentsShirleyEnergyThe U.S. Department ofEnergy(Department orAn exampleThe StartupagendaitsState8333

  2. State Overview

    Broader source: Energy.gov (indexed) [DOE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of Natural GasAdjustmentsShirleyEnergyThe U.S. Department ofEnergy(Department orAn exampleThe StartupagendaitsState83337

  3. State Overview

    Broader source: Energy.gov (indexed) [DOE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of Natural GasAdjustmentsShirleyEnergyThe U.S. Department ofEnergy(Department orAn exampleThe StartupagendaitsState8333755

  4. United States

    Office of Environmental Management (EM)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of Natural GasAdjustmentsShirley Ann Jackson About1996HowFOAShowing YouNeedof EnergyMeeting - MarchUSPS:1 United States

  5. United States

    Office of Environmental Management (EM)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of Natural GasAdjustmentsShirley Ann Jackson About1996HowFOAShowing YouNeedof EnergyMeeting - MarchUSPS:1 United States7

  6. United States

    Office of Environmental Management (EM)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of Natural GasAdjustmentsShirley Ann Jackson About1996HowFOAShowing YouNeedof EnergyMeeting - MarchUSPS:1 United States78

  7. State Energy Program Helps States Plan

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Energy Program Helps States Plan and Implement Energy Efficiency The U.S. Department of Energy (DOE) State Energy Program (SEP) provides grants and technical assis- tance to states...

  8. United States Environmental

    E-Print Network [OSTI]

    Al Faruque, Mohammad Abdullah

    Protect Your Family From Lead in Your Home United States Environmental Protection Agency United States Consumer Product Safety Commission United States Department of Housing and Urban Development

  9. 21. Khaykovich, B. et al. Vortex-lattice phase transitions in Bi2Sr2CaCu2O8 crystals with different oxygen stoichiometry. Phys. Rev. Lett. 76, 25552558 (1996).

    E-Print Network [OSTI]

    Zeldov, Eli

    1996-01-01

    . Williams, G. A. Vortex-loop phase transitions in liquid helium, cosmic strings, and high-Tc super the discovery of ®rst-order inverse melting of the lattice formed by magnetic ¯ux lines in a high-temperature of magnetic ¯ux lattice melting and decomposition in the high-Tc superconductor Bi2.15Sr1.95CaCu2O8+x. Nature

  10. VOLUME 82, NUMBER 6 P H Y S I C A L R E V I E W L E T T E R S 8 FEBRUARY 1999 Vortex-Loop Phase Transitions in Liquid Helium, Cosmic Strings,

    E-Print Network [OSTI]

    Williams, Gary A.

    Transitions in Liquid Helium, Cosmic Strings, and High-Tc Superconductors Gary A. Williams Department a increases as the temperature is increased, and the density is finally driven to zero at Tc by loopsVOLUME 82, NUMBER 6 P H Y S I C A L R E V I E W L E T T E R S 8 FEBRUARY 1999 Vortex-Loop Phase

  11. PUBLISHED ONLINE: 24 MAY 2009 | DOI: 10.1038/NPHYS1277 Vortex nucleation as a case study of symmetry

    E-Print Network [OSTI]

    Loss, Daniel

    of physics. In particular, they describe with excellent accuracy trapped Bose­Einstein condensates. A generic nucleation in a rotating Bose­Einstein condensate. A slow sweep of the rotation frequency changes the state of applicability of the mean field concerns a weakly interacting quantum Bose gas and Bose­Einstein condensation2

  12. Erratum: Evolution of antiferromagnetic susceptibility under uniaxial

    Office of Scientific and Technical Information (OSTI)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefieldSulfate Reducing(Journal Article) | SciTech(Journal(Patent)pressure in Ba ( Fe 1 - x Co x ) 2 As 2

  13. Emergent infinite-randomness fixed points from the extensive random bipartitions of the spin-1 Affleck-Kennedy-Lieb-Tasaki topological state

    E-Print Network [OSTI]

    Min Lu; Rajesh Narayanan; Xin Wan; Guang-Ming Zhang

    2015-02-07

    Quantum entanglement under an extensive bipartition can reveal the critical boundary theory of a topological phase in the parameter space. In this study we demonstrate that the infinite-randomness fixed point for spin-1/2 degrees of freedom can emerge from an extensive random bipartition of the spin-1 Affleck-Kennedy-Lieb-Tasaki chain. The nested entanglement entropy of the ground state of the reduced density matrix exhibits a logarithmic scaling with an effective central charge $\\tilde{c} = 0.72 \\pm 0.02 \\approx \\ln 2$. We further discuss, in the language of bulk quantum entanglement, how to understand all phase boundaries and the surrounding Griffiths phases for the antiferromagnetic Heisenberg spin-1 chain with quenched disorder and dimerization.

  14. Competing magnetic ground states in nonsuperconducting Ba(Fe1-xCrx)2As2 as seen via neutron diffraction

    SciTech Connect (OSTI)

    Marty, Karol J [ORNL; Christianson, Andrew D [ORNL; Wang, C H [Oak Ridge National Laboratory (ORNL); Matsuda, Masaaki [ORNL; Cao, Huibo [ORNL; VanBebber, L. H. [University of Tennessee, Knoxville (UTK); Zarestky, Jerel L [ORNL; Singh, David J [ORNL; Sefat, A. S. [Oak Ridge National Laboratory (ORNL); Lumsden, Mark D [ORNL

    2011-01-01

    We present neutron diffraction measurements on single-crystal samples of nonsuperconducting Ba(Fe{sub 1-x}Cr{sub x}){sub 2}As{sub 2} as a function of Cr doping for 0 {le} x {le} 0.47. The average spin-density-wave moment is independent of concentration for x {le} 0.2 and decreases rapidly for x {ge} 0.3. For concentrations in excess of 30% chromium, we find a new competing magnetic phase consistent with G-type antiferromagnetism which rapidly becomes the dominant magnetic ground state. Strong magnetism is observed for all concentrations measured, naturally explaining the absence of superconductivity in the Cr-doped materials.

  15. Substitution of Ni for Fe in superconducting Fe?.??Te?.?Se?.? depresses the normal-state conductivity but not the magnetic spectral weight

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wang, Jinghui; Tranquada, J. M.; Zhong, Ruidan; Li, Shichao; Gan, Yuan; Xu, Zhijun; Zhang, Cheng; Ozaki, T.; Matsuda, M.; Zhao, Yang; et al

    2015-01-05

    We have performed systematic resistivity and inelastic neutron scattering measurements on Fe?.???zNizTe?.?Se?.? samples to study the impact of Ni substitution on the transport properties and the low-energy (? 12 meV) magnetic excitations. It is found that, with increasing Ni doping, both the conductivity and superconductivity are gradually suppressed; in contrast, the low-energy magnetic spectral weight changes little. Comparing with the impact of Co and Cu substitution, we find that the effects on conductivity and superconductivity for the same degree of substitution grow systematically as the atomic number of the substituent deviates from that of Fe. The impact of the substituentsmore »as scattering centers appears to be greater than any contribution to carrier concentration. The fact that low-energy magnetic spectral weight is not reduced by increased electron scattering indicates that the existence of antiferromagnetic correlations does not depend on electronic states close to the Fermi energy.« less

  16. Substitution of Ni for Fe in superconducting Fe?.??Te?.?Se?.? depresses the normal-state conductivity but not the magnetic spectral weight

    SciTech Connect (OSTI)

    Wang, Jinghui [Nanjing Univ., Nanjing (China); Tranquada, J. M. [Brookhaven National Lab. (BNL), Upton, NY (United States); Zhong, Ruidan [Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., Stony Brook, NY (United States); Li, Shichao [Nanjing Univ., Nanjing (China); Gan, Yuan [Nanjing Univ., Nanjing (China); Xu, Zhijun [Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Zhang, Cheng [Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., Stony Brook, NY (United States); Ozaki, T. [Brookhaven National Lab. (BNL), Upton, NY (United States); Matsuda, M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Zhao, Yang [National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States); Univ. of Maryland, College Park, MD (United States); Li, Qiang [Brookhaven National Lab. (BNL), Upton, NY (United States); Xu, G. [Brookhaven National Lab. (BNL), Upton, NY (United States); Gu, Genda [Brookhaven National Lab. (BNL), Upton, NY (United States); Birgeneau, R. J. [Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Wen, Jinsheng [Nanjing Univ., Nanjing (China)

    2015-01-01

    We have performed systematic resistivity and inelastic neutron scattering measurements on Fe?.???zNizTe?.?Se?.? samples to study the impact of Ni substitution on the transport properties and the low-energy (? 12 meV) magnetic excitations. It is found that, with increasing Ni doping, both the conductivity and superconductivity are gradually suppressed; in contrast, the low-energy magnetic spectral weight changes little. Comparing with the impact of Co and Cu substitution, we find that the effects on conductivity and superconductivity for the same degree of substitution grow systematically as the atomic number of the substituent deviates from that of Fe. The impact of the substituents as scattering centers appears to be greater than any contribution to carrier concentration. The fact that low-energy magnetic spectral weight is not reduced by increased electron scattering indicates that the existence of antiferromagnetic correlations does not depend on electronic states close to the Fermi energy.

  17. Substitution of Ni for Fe in superconducting Fe?.??Te?.?Se?.? depresses the normal-state conductivity but not the magnetic spectral weight

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wang, Jinghui [Nanjing Univ., Nanjing (China); Tranquada, J. M. [Brookhaven National Lab. (BNL), Upton, NY (United States); Zhong, Ruidan [Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., Stony Brook, NY (United States); Li, Shichao [Nanjing Univ., Nanjing (China); Gan, Yuan [Nanjing Univ., Nanjing (China); Xu, Zhijun [Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Zhang, Cheng [Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., Stony Brook, NY (United States); Ozaki, T. [Brookhaven National Lab. (BNL), Upton, NY (United States); Matsuda, M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Zhao, Yang [National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States); Univ. of Maryland, College Park, MD (United States); Li, Qiang [Brookhaven National Lab. (BNL), Upton, NY (United States); Xu, G. [Brookhaven National Lab. (BNL), Upton, NY (United States); Gu, Genda [Brookhaven National Lab. (BNL), Upton, NY (United States); Birgeneau, R. J. [Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Wen, Jinsheng [Nanjing Univ., Nanjing (China)

    2015-01-01

    We have performed systematic resistivity and inelastic neutron scattering measurements on Fe?.???zNizTe?.?Se?.? samples to study the impact of Ni substitution on the transport properties and the low-energy (? 12 meV) magnetic excitations. It is found that, with increasing Ni doping, both the conductivity and superconductivity are gradually suppressed; in contrast, the low-energy magnetic spectral weight changes little. Comparing with the impact of Co and Cu substitution, we find that the effects on conductivity and superconductivity for the same degree of substitution grow systematically as the atomic number of the substituent deviates from that of Fe. The impact of the substituents as scattering centers appears to be greater than any contribution to carrier concentration. The fact that low-energy magnetic spectral weight is not reduced by increased electron scattering indicates that the existence of antiferromagnetic correlations does not depend on electronic states close to the Fermi energy.

  18. Excitations and possible bound states in the S = {1/2} alternating chain compound (VO){sub 2}P{sub 2}O{sub 7}

    SciTech Connect (OSTI)

    Tennant, D.A.; Nagler, S.E.; Sales, B.C. [Oak Ridge National Lab., TN (United States)] [and others

    1997-07-30

    Magnetic excitations in an array of (VO){sub 2}P{sub 2}O{sub 7} single crystals have been measured using inelastic neutron scattering. Until now, (VO){sub 2}P{sub 2}O{sub 7} has been thought of as a two-leg antiferromagnetic Heisenberg spin ladder with chains running in the a-direction. The present results show unequivocally that (VO){sub 2}P{sub 2}O{sub 7} is best described as an alternating spin-chain directed along the crystallographic b-direction. In addition to the expected magnon with magnetic zone-center energy gap {Delta} = 3.1 meV, a second excitation is observed at an energy just below 2{Delta}. The higher mode may be a triplet two-magnon bound state. Numerical results in support of bound modes are presented.

  19. The Meissner Effect and Vortex Expulsion in Color-Superconducting Quark stars, and its Role for Re-heating of Magnetars

    E-Print Network [OSTI]

    Brian Niebergal; Rachid Ouyed; Rodrigo Negreiros; Fridolin Weber

    2010-01-29

    Compact stars made of quark matter rather than confined hadronic matter, are expected to form a color superconductor. This superconductor ought to be threaded with rotational vortex lines, within which the star's interior magnetic field is at least partially confined. The vortices (and thus magnetic flux) would be expelled from the star during stellar spin-down, leading to magnetic reconnection at the surface of the star and the prolific production of thermal energy. In this paper, we show that this energy release can re-heat quark stars to exceptionally high temperatures, such as observed for Soft Gamma Repeaters (SGRs), Anomalous X-Ray pulsars (AXPs), and X-ray dim isolated neutron stars (XDINs). Moreover, our numerical investigations of the temperature evolution, spin-down rate, and magnetic field behavior of such superconducting quark stars suggest that SGRs, AXPs, and XDINs may be linked ancestrally. Finally, we discuss the possibility of a time delay before the star enters the color superconducting phase, which can be used to estimate the density at which quarks deconfine. From observations, we find this density to be of the order of five times that of nuclear saturation.

  20. Nozick's minimal state

    E-Print Network [OSTI]

    Russell, Darrell James

    1995-01-01

    In his book, Anarchy , State, and Utopia, Robert Nozick argues that the only state that can be justified is the minimal state, a state limited to providing protection for all its citizens. Nozick explains how a minimal state could naturally develop...

  1. San Francisco State University

    E-Print Network [OSTI]

    Ovchinnikov, Sergei

    San Francisco State University Multi-Hazard Emergency Operations Plan August 2014 Preparedness Response Recovery Mitigation #12;BLANK PAGE #12;Preface #12;BLANK PAGE #12;San Francisco State University.........................................................................................................vi Profile of San Francisco State University

  2. United States Department of

    E-Print Network [OSTI]

    United States Department of Agriculture Forest Service Pacific Southwest Forest and Range symposium dealing with this subject in the western United States, the papers presented address current ........................................................................................................................................ 1 Annosus Root Disease in Europe and the Southeastern United States: Occurrence, Research

  3. Are Quantum States Subjective?

    E-Print Network [OSTI]

    R. K. Pradhan

    2012-02-22

    The subjective nature of the quantum states is brought out and it is argued that the objective state assignment is subsequent to the subjective state of the observer regarding his state of knowledge about the system. The collapse postulate is examined in detail to bring out the inherent subjectivity of the quantum state. The role of doubt and faith in quantum state assignment is examined.

  4. United States Department of

    E-Print Network [OSTI]

    Kurapov, Alexander

    A United States Department of Agriculture Forest Service Pacific Northwest Research Station General, land management, carbon sequestration, carbon markets, United States. #12;ii Executive Summary

  5. United States Department of

    E-Print Network [OSTI]

    United States Department of Agriculture Forest Service Intermountain Research Station General acrossthe United States provide estimates of the amount of erosion reductionon forest roadsfrom

  6. United States Department of

    E-Print Network [OSTI]

    Wang, Changlu

    United States Department of Agriculture Rural Business- Cooperative Service Research Report 157, concentration, globalization, agency theory Cooperatives in a Changing Global Food System United States

  7. Observation of high-spin mixed oxidation state of cobalt in ceramic Co{sub 3}TeO{sub 6}

    SciTech Connect (OSTI)

    Singh, Harishchandra E-mail: singh85harish@rrcat.gov.in; Ghosh, Haranath; Sinha, A. K.; Chandrasekhar Rao, T. V.; Rajput, Parasmani

    2014-12-07

    We report coexistence of high spin Co{sup 3+} and Co{sup 2+} in ceramic Co{sub 3}TeO{sub 6} using X-ray Absorption Near Edge Structure (XANES), DC magnetization, and first principles ab-initio calculations. The main absorption line of cobalt Co K-edge XANES spectra, along with a linear combination fit, led us to estimate relative concentration of Co{sup 2+} and Co{sup 3+}as 60:40. The pre edge feature of XANES spectrum shows crystal field splitting of ?1.26?eV between e{sub g} and t{sub 2g} states, suggesting a mixture of high spin states of both Co{sup 2+} and Co{sup 3+}. Temperature dependent high field DC magnetization measurements reveal dominant antiferromagnetic order with two Neel temperatures (T{sub N1}???29?K and T{sub N2}???18?K), consistent with single crystal study. A larger effective magnetic moment is observed in comparison to that reported for single crystal (which contains only Co{sup 2+}), supports our inference that Co{sup 3+} exists in high spin state. Furthermore, we show that both Co{sup 2+} and Co{sup 3+} being in high spin states constitute a favorable ground state through first principles ab-initio calculations, where Rietveld refined synchrotron X-ray diffraction data are used as input.

  8. VOLUME 81, NUMBER 23 P H Y S I C A L R E V I E W L E T T E R S 7 DECEMBER 1998 Semiclassical Eigenstates of Four-Sublattice Antiferromagnets

    E-Print Network [OSTI]

    Henley, Christopher L.

    , Cornell University, Ithaca, New York 14853-2501 (Received 6 July 1998) Applying Bohr? The most common analysis is to extrapolate the ground-state correlations and energy gap infinite size. An alternative approach uses the finite-size splittings and symmetries of an entire family of low-lying states

  9. Discrimination between pure states and mixed states

    E-Print Network [OSTI]

    Chi Zhang; Guoming Wang; Mingsheng Ying

    2007-02-09

    In this paper, we discuss the problem of determining whether a quantum system is in a pure state, or in a mixed state. We apply two strategies to settle this problem: the unambiguous discrimination and the maximum confidence discrimination. We also proved that the optimal versions of both strategies are equivalent. The efficiency of the discrimination is also analyzed. This scheme also provides a method to estimate purity of quantum states, and Schmidt numbers of composed systems.

  10. State Energy Risk Assessment Initiative - State Energy Risk Profiles...

    Energy Savers [EERE]

    Mission Energy Infrastructure Modeling and Analysis State Energy Risk Assessment Initiative - State Energy Risk Profiles State Energy Risk Assessment Initiative - State...

  11. Colorado State University Colorado State University

    E-Print Network [OSTI]

    to promote the liberal and practical education of the industrial classes in the several pursuits medicine. Colorado State University has a unique mission in the state of Colorado. The land-grant concept global environment, and has a commitment to excellence in international education in all its

  12. Substitution of Ni for Fe in superconducting Fe0.98Te0.5Se0.5 depresses the normal-state conductivity but not the magnetic spectral weight

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wang, Jinghui; Zhong, Ruidan; Li, Shichao; Gan, Yuan; Xu, Zhijun; Zhang, Cheng; Ozaki, T.; Matsuda, M.; Zhao, Yang; Li, Qiang; et al

    2015-01-05

    We have performed systematic resistivity and inelastic neutron scattering measurements on Fe?.???zNizTe?.?Se?.? samples to study the impact of Ni substitution on the transport properties and the low-energy (? 12 meV) magnetic excitations. It is found that, with increasing Ni doping, both the conductivity and superconductivity are gradually suppressed; in contrast, the low-energy magnetic spectral weight changes little. Comparing with the impact of Co and Cu substitution, we find that the effects on conductivity and superconductivity for the same degree of substitution grow systematically as the atomic number of the substituent deviates from that of Fe. The impact of the substituentsmore »as scattering centers appears to be greater than any contribution to carrier concentration. The fact that low-energy magnetic spectral weight is not reduced by increased electron scattering indicates that the existence of antiferromagnetic correlations does not depend on electronic states close to the Fermi energy.« less

  13. Far-from-equilibrium field theory of many-body quantum spin systems: Prethermalization and relaxation of spin spiral states in three dimensions

    E-Print Network [OSTI]

    Mehrtash Babadi; Eugene Demler; Michael Knap

    2015-10-13

    We study theoretically the far-from-equilibrium relaxation dynamics of spin spiral states in the three dimensional isotropic Heisenberg model. The investigated problem serves as an archetype for understanding quantum dynamics of isolated many-body systems in the vicinity of a spontaneously broken continuous symmetry. We present a field-theoretical formalism that systematically improves on mean-field for describing the real-time quantum dynamics of generic spin-1/2 systems. This is achieved by mapping spins to Majorana fermions followed by a 1/N expansion of the resulting two-particle irreducible (2PI) effective action. Our analysis reveals rich fluctuation-induced relaxation dynamics in the unitary evolution of spin spiral states. In particular, we find the sudden appearance of long-lived prethermalized plateaus with diverging lifetimes as the spiral winding is tuned toward the thermodynamically stable ferro- or antiferromagnetic phases. The emerging prethermalized states are characterized by different bosonic modes being thermally populated at different effective temperatures, and by a hierarchical relaxation process reminiscent of glassy systems. Spin-spin correlators found by solving the non-equilibrium Bethe-Salpeter equation provide further insight into the dynamic formation of correlations, the fate of unstable collective modes, and the emergence of fluctuation-dissipation relations. Our predictions can be verified experimentally using recent realizations of spin spiral states with ultracold atoms in a quantum gas microscope [S. Hild, et al. Phys. Rev. Lett. 113, 147205 (2014)].

  14. Langevin vortex dynamics for a layered superconductor in the lowest-Landau-level approximation W. A. Al-Saidi* and D. Stroud

    E-Print Network [OSTI]

    Stroud, David

    . Al-Saidi* and D. Stroud Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA

  15. Experimental and semiempirical method to determine the Pauli-limiting field in quasi-two-dimensional superconductors as applied to ?-(BEDT-TTF)2Cu(NCS)2: strong evidence of a FFLO state

    SciTech Connect (OSTI)

    Agosta, C. C.; Jin, J.; Coniglio, W. A.; Smith, B. E.; Cho, K.; Mihut, I.; Martin, C.; Tozer, S. W.; Murphy, T. P.; Palm, E. C.; Schlueter, J. A.; Kurmoo, M.

    2012-01-01

    We present upper critical field data for {kappa}-(BEDT-TTF){sub 2}Cu(NCS){sub 2} with the magnetic field close to parallel and parallel to the conducting layers. We show that we can eliminate the effect of vortex dynamics in these layered materials if the layers are oriented within 0.3-inch of parallel to the applied magnetic field. Eliminating vortex effects leaves one remaining feature in the data that corresponds to the Pauli paramagnetic limit (H{sub p}). We propose a semiempirical method to calculate the H{sub p} in quasi-2D superconductors. This method takes into account the energy gap of each of the quasi-2D superconductors, which is calculated from specific-heat data, and the influence of many-body effects. The calculated Pauli paramagnetic limits are then compared to critical field data for the title compound and other organic conductors. Many of the examined quasi-2D superconductors, including the above organic superconductors and CeCoIn{sub 5}, exhibit upper critical fields that exceed their calculated H{sub p} suggesting unconventional superconductivity. We show that the high-field low-temperature state in {kappa}-(BEDT-TTF){sub 2}Cu(NCS){sub 2} is consistent with the Fulde-Ferrell-Larkin-Ovchinnikov state.

  16. United States Department of

    E-Print Network [OSTI]

    United States Department of Agriculture Forest Service Pacific Northwest Research Station Research, and export from 1997 to 2010, for main world regions and the United States. Detailed tables by country

  17. United States Department of

    E-Print Network [OSTI]

    United States Department of Agriculture Forest Service Northeastern Research Station Research Paper-Central United States (Monserud and Ek 1977; Monserud 1987). This model was used within the framework of FOREST

  18. United States Department of

    E-Print Network [OSTI]

    United States Department of Agriculture Usual Planting and Harvesting Dates for U.S. Field Crops million acres of barley were harvested in the United States (U.S.) during 1996. After reaching a peak

  19. United States Department of

    E-Print Network [OSTI]

    United States Department of Agriculture Forest Service Pacific Northwest Research Station Research, import, and export from 1997 to 2010, for main world regions and the United States. Detailed tables

  20. States & Emerging Energy Technologies

    Office of Energy Efficiency and Renewable Energy (EERE)

    This presentation, given through the DOE's Technical Assitance Program (TAP), provides information on States & Emerging Energy Technologies.

  1. AASG STATE GDR

    Energy Science and Technology Software Center (OSTI)

    003198MLTPL00 AASG State Geothermal Data Repository for the National Geothermal Data System.  http://repository.stategeothermaldata.org/repository/ 

  2. Sustainability Cal State Fullerton

    E-Print Network [OSTI]

    de Lijser, Peter

    Sustainability at Cal State Fullerton A Report from the Sustainability Initiative Study Group October 28, 2008 #12;Sustainability at Cal State Fullerton A Report from the Sustainability Initiative Safety Sally Yassine Contracts & Procurement #12;Sustainability at Cal State Fullerton A Report from

  3. FISHERY STATISTICS UNITED STATES

    E-Print Network [OSTI]

    FISHERY STATISTICS OF THE UNITED STATES 1972 STATISTICAL DIGEST NO. 66 Prepared by STATISTICS;ACKNOWLEDGMENTS The data in this edition of "Fishery Statistics of the United States" were collected in co- operation with the various States and tabulated by the staff of the Statistics and Market News Division

  4. Engineering United States

    E-Print Network [OSTI]

    Bledsoe, Brian

    Schultze, State Biologist, SCS, Davis, CA Arthur Sherman, Wetland Ecologist, ManTech Env. Technology, Inc., EPA Environmental Research Laboratory, Corvallis, OR Bob Snieckus, Landscape Architect, SCS, Davis, CA Wayne Talbot, Assistant State Conservation Engineer, SCS, Alexandria, LA Bill Welker, State Biologist

  5. United States Department of

    E-Print Network [OSTI]

    United States Department of Agriculture Forest Service Northeastern Research Station General Estimates for Forest Types of the United States James E. Smith Linda S. Heath Kenneth E. Skog Richard A forest types within 10 regions of the United States. Separate tables were developed for afforestation

  6. United States of Agriculture

    E-Print Network [OSTI]

    United States Department of Agriculture Forest Service Pacific Southwest Research Station General,000 xylem resin samples of pine (Pinus) species and hybrids--largely from the western United States locations in the eastern and southern United States. Cover Image: Chapter 6, Figure 6-2. #12;Xylem

  7. United States Department of

    E-Print Network [OSTI]

    Holberton, Rebecca L.

    United States Department of Agriculture Forest Service Northeastern Research Station General Technical Report NE-318 Atlas of Climate Change Effects in 150 Bird Species of the Eastern United States Service 359 Main Road Delaware, OH 43015 USA #12;United States Department of Agriculture Forest Service

  8. United States Department of

    E-Print Network [OSTI]

    United States Department of Agriculture Forest Service Northeastern Research Station Research Paper NE-722 James E. Smith Linda S. Heath A Model of Forest Floor Carbon Mass for United States Forest contiguous United States. Manuscript received for publication 22 April 2002 #12;A Model of Forest Floor

  9. United States Department of

    E-Print Network [OSTI]

    United States Department of Agriculture Forest Service Southern Research Station General Technical United States. In: Rauscher, H. Michael, and Kurt Johnsen, eds. Southern forest science: past, present Trends in the Southern United States Robert A. Mickler, James E. Smith, and Linda S. Heath1 Abstract

  10. United States Department of

    E-Print Network [OSTI]

    United States Department of Agriculture Forest Service Northeastern Research Station General reported in USDA Forest Service surveys for forests of the conterminous United States. Developed for use estimates are provided for regional tree-mass totals using summary forest statistics for the United States

  11. United States Nuclear Regulatory

    E-Print Network [OSTI]

    United States Nuclear Regulatory Commission United States Department of Energy United States.S. Nuclear Regulatory Commission Washington, DC 20555-0001 E-mail: DISTRIBUTION@nrc.gov Facsimile: 301; and Commission papers and their attachments. NRC publications in the NUREG series, NRC regulations, and Title 10

  12. Fourth Generation Bound States

    E-Print Network [OSTI]

    Koji Ishiwata; Mark B. Wise

    2011-05-25

    We investigate the spectrum and wave functions of {\\bar q}'q' bound states for heavy fourth generation quarks (q') that have a very small mixing with the three observed generations of standard model quarks. Such bound states come with different color, spin and flavor quantum numbers. Since the fourth generation Yukawa coupling, \\lambda_{q'}, is large we include all perturbative corrections to the potential between the heavy quark and antiquark of order \\lambda_{q'}^2N_c/16\\pi^2 where N_c is the number of colors, as well as relativistic corrections suppressed by (v/c)^2. We find that the lightest fourth generation quark masses for which a bound state exists for color octet states. For the the color singlet states, which always have a bound state, we analyze the influence that the Higgs couplings have on the size and binding energy of the bound states.

  13. State Opportunities for Action: Update of States' CHP Activities...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Opportunities for Action: Update of States' CHP Activities (ACEEE), October 2003 State Opportunities for Action: Update of States' CHP Activities (ACEEE), October 2003 This 2003...

  14. State Clean Energy Policies Analysis (SCEPA): State Policy and...

    Open Energy Info (EERE)

    State Clean Energy Policies Analysis (SCEPA): State Policy and the Pursuit of Renewable Energy Manufacturing Jump to: navigation, search Tool Summary LAUNCH TOOL Name: State Clean...

  15. State and Local Code Implementation: State Energy Officials ...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    State Energy Officials - 2014 BTO Peer Review State and Local Code Implementation: State Energy Officials - 2014 BTO Peer Review Presenter: Chris Wagner, National Association of...

  16. State Technologies Advancement Collaborative

    SciTech Connect (OSTI)

    David S. Terry

    2012-01-30

    The U. S. Department of Energy (DOE), National Association of State Energy Officials (NASEO), and Association of State Energy Research and Technology Transfer Institutions (ASERTTI) signed an intergovernmental agreement on November 14, 2002, that allowed states and territories and the Federal Government to better collaborate on energy research, development, demonstration and deployment (RDD&D) projects. The agreement established the State Technologies Advancement Collaborative (STAC) which allowed the states and DOE to move RDD&D forward using an innovative competitive project selection and funding process. A cooperative agreement between DOE and NASEO served as the contracting instrument for this innovative federal-state partnership obligating funds from DOE's Office of Energy Efficiency and Renewable Energy and Office of Fossil Energy to plan, fund, and implement RDD&D projects that were consistent with the common priorities of the states and DOE. DOE's Golden Field Office provided Federal oversight and guidance for the STAC cooperative agreement. The STAC program was built on the foundation of prior Federal-State efforts to collaborate on and engage in joint planning for RDD&D. Although STAC builds on existing, successful programs, it is important to note that it was not intended to replace other successful joint DOE/State initiatives such as the State Energy Program or EERE Special Projects. Overall the STAC process was used to fund, through three competitive solicitations, 35 successful multi-state research, development, deployment, and demonstration projects with an overall average non-federal cost share of 43%. Twenty-two states were awarded at least one prime contract, and organizations in all 50 states and some territories were involved as subcontractors in at least one STAC project. Projects were funded in seven program areas: (1) Building Technologies, (2) Industrial Technologies, (3) Transportation Technologies, (4) Distributed Energy Resources, (5) Hydrogen Technology Learning Centers, (6) Fossil Energy, and (7) Rebuild America.

  17. Correlation between magnetic spin structure and the three-dimensional geometry in chemically synthesized nanoscale magnetite rings

    E-Print Network [OSTI]

    Dunin-Borkowski, Rafal E.

    yielding an intermediate magnetic state between the vortex state and the tube state is found closure vortex states but in rings with thickness variations, an effective stray field occurs. Using. The interaction between exchange coupled rings leads to antiparallel vortex states and extended onion states

  18. Multiferroic tunnel junctions and ferroelectric control of magnetic state at interface (invited)

    SciTech Connect (OSTI)

    Yin, Y. W.; Raju, M.; Li, Qi; Hu, W. J.; Burton, J. D.; Gruverman, A.; Tsymbal, E. Y.; Kim, Y.-M.; Borisevich, A. Y.; Pennycook, S. J.; Yang, S. M.; Noh, T. W.; Li, X. G.; Zhang, Z. D.

    2015-05-07

    As semiconductor devices reach ever smaller dimensions, the challenge of power dissipation and quantum effect place a serious limit on the future device scaling. Recently, a multiferroic tunnel junction (MFTJ) with a ferroelectric barrier sandwiched between two ferromagnetic electrodes has drawn enormous interest due to its potential applications not only in multi-level data storage but also in electric field controlled spintronics and nanoferronics. Here, we present our investigations on four-level resistance states, giant tunneling electroresistance (TER) due to interfacial magnetoelectric coupling, and ferroelectric control of spin polarized tunneling in MFTJs. Coexistence of large tunneling magnetoresistance and TER has been observed in manganite/(Ba, Sr)TiO{sub 3}/manganite MFTJs at low temperatures and room temperature four-resistance state devices were also obtained. To enhance the TER for potential logic operation with a magnetic memory, La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/BaTiO{sub 3}/La{sub 0.5}Ca{sub 0.5}MnO{sub 3} /La{sub 0.7}Sr{sub 0.3}MnO{sub 3} MFTJs were designed by utilizing a bilayer tunneling barrier in which BaTiO{sub 3} is ferroelectric and La{sub 0.5}Ca{sub 0.5}MnO{sub 3} is close to ferromagnetic metal to antiferromagnetic insulator phase transition. The phase transition occurs when the ferroelectric polarization is reversed, resulting in an increase of TER by two orders of magnitude. Tunneling magnetoresistance can also be controlled by the ferroelectric polarization reversal, indicating strong magnetoelectric coupling at the interface.

  19. Painlevé IV Coherent States

    E-Print Network [OSTI]

    David Bermudez; Alonso Contreras-Astorga; David J. Fernández C

    2014-02-24

    A simple way to find solutions of the Painlev\\'e IV equation is by identifying Hamiltonian systems with third-order differential ladder operators. Some of these systems can be obtained by applying supersymmetric quantum mechanics (SUSY QM) to the harmonic oscillator. In this work, we will construct families of coherent states for such subset of SUSY partner Hamiltonians which are connected with the Painlev\\'e IV equation. First, these coherent states are built up as eigenstates of the annihilation operator, then as displaced versions of the extremal states, both involving the third-order ladder operators, and finally as extremal states which are also displaced but now using the so called linearized ladder operators. To each SUSY partner Hamiltonian corresponds two families of coherent states: one inside the infinite subspace associated with the isospectral part of the spectrum and another one in the finite subspace generated by the states created through the SUSY technique.

  20. Energy Standards for State Agencies

    Broader source: Energy.gov [DOE]

    State departments and agencies are encouraged to employ the latest energy-conservation practices in the design, construction, renovation, operation and maintenance of state facilities. All state ...

  1. Hadronic Final States

    E-Print Network [OSTI]

    B. R. Webber

    1995-10-12

    The following aspects of hadronic final states in deep inelastic lepton scattering are reviewed: measuring $alpha_s$ from multi-jet production rates and event shapes; alternative jet algorithms for DIS; power-suppressed corrections to event shapes; comparing jet fragmentation in $e^+e^-$ annihilation and DIS; final states in the BFKL and CCFM formulations of small-$x$ dynamics; exotic (instanton-induced) final states.

  2. State of the States: Fuel Cells in America 2012 | Department...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    State of the States: Fuel Cells in America 2012 State of the States: Fuel Cells in America 2012 This report, written by Fuel Cells 2000 and partially funded by the U.S. Department...

  3. United States Department of

    E-Print Network [OSTI]

    ..............................................................................2 Solid Waste Management .........................................................................3 ....................................................................................4 Solid Waste ManagementUnited States Department of Returns on InvestmentsAgriculture Forest Service in Management Sciences

  4. State Energy Strategic Planning

    Office of Energy Efficiency and Renewable Energy (EERE)

    U.S. Department of Energy (DOE) Technical Assistance Program (TAP) presentation at a TAP webinar held on April 3, 2013 and dealing with state energy strategic planning.

  5. United States Department of

    E-Print Network [OSTI]

    United States Department of Agriculture Forest Service Pacific Southwest Research Station General assigned to the Station's research unit studying the regeneration of California forests

  6. United States Department of

    E-Print Network [OSTI]

    United States Department of Agriculture MIX: A Computer Program to Evaluate Forest Service, a research entomologist, is in charge of the unit developing improved technology for integrated management

  7. United States Department of

    E-Print Network [OSTI]

    United States Department of Agriculture Forest Service Pacific Southwest Research Station General Programs: A Review of Cognitive and Behavioral Studies Introduction Recent wildfires in the Western United

  8. United States Department of

    E-Print Network [OSTI]

    United States Department of Agriculture Forest Service Pacific Southwest Forest and Range to the Chaparral Prescribed Fire Research Unit, headquartered at Riverside, California. Publisher: Pacific

  9. United States Department of

    E-Print Network [OSTI]

    United States Department of Agriculture Forest Service Pacific Southwest Research Station General is a Research Ecologist at the Station's Timber Management/Wildlife Habitat Interactions Unit, Redwood Sciences

  10. United States of Agriculture

    E-Print Network [OSTI]

    United States Department of Agriculture Forest Service Pacific Southwest Research Station General scientist with the Station's Wildland Recreation and Urban Cultures Research Unit, 4955 Canyon Crest Drive

  11. United States Department of

    E-Print Network [OSTI]

    94701 United States Department of Agriculture Forest Service Pacific Southwest Forest and Range of California, Berkeley, and a cooperator with the Research Unit. #12;Acknowledgments We especially acknowledge

  12. United States Department of

    E-Print Network [OSTI]

    United States Department of Agriculture Forest Service Pacific Southwest Forest and Range to the Station's chaparral and related ecosystems research unit, with headquarters at Riverside, California. He

  13. United States Department of

    E-Print Network [OSTI]

    United States Department of California Oaks: A Bibliography Agriculture Forest Service Pacific forester in the Station's Forest Regeneration Research Unit, at Redding, California. He holds bachelor

  14. United States Department of

    E-Print Network [OSTI]

    United States Department of Agriculture Forest Service Pacific Southwest Research Station General is a supervisory research entomologist in the Station's Regeneration Insect Research Unit in Berkeley. W. WAYNE

  15. dynamo_double_vortex.pdf

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    of triggering. * During a VDE, the gas jet is triggered when the vertical position of the plasma center drops by a set distance. * There is no straightforward way for a proper...

  16. Vortex Energy | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QA J-E-1 SECTION J APPENDIX ECoop IncIowa (Utility Company)Idaho)

  17. Oklahoma State University Purchasing Card

    E-Print Network [OSTI]

    Veiga, Pedro Manuel Barbosa

    Oklahoma State University Purchasing Card Guidelines Oklahoma State University Fiscal and Administrative Compliance 306 Whitehurst Stillwater, OK 74078 http://faac.okstate.edu August 2011 Oklahoma State University Purchasing Card Guidelines Fiscal and Administrative Compliance Oklahoma State University #12;Page

  18. OKLAHOMA STATE June 30, 2009

    E-Print Network [OSTI]

    Veiga, Pedro Manuel Barbosa

    OKLAHOMA STATE UNIVERSITY June 30, 2009 #12;OKLAHOMA STATE UNIVERSITY June 30, 2009 AUDITED ..........................................................................................................56 Discretely Presented Component Units Oklahoma State University Foundation..............................................................................................71 OKLAHOMA STATE UNIVERSITY DETAILED SCHEDULE OF EXPENDITURES OF FEDERAL AWARDS General University

  19. OKLAHOMA STATE June 30, 2011

    E-Print Network [OSTI]

    Veiga, Pedro Manuel Barbosa

    OKLAHOMA STATE UNIVERSITY June 30, 2011 #12;OKLAHOMA STATE UNIVERSITY June 30, 2011 AUDITED.................................................................................................59 Discretely Presented Component Units Oklahoma State University Foundation..............................................................................................76 OKLAHOMA STATE UNIVERSITY DETAILED SCHEDULE OF EXPENDITURES OF FEDERAL AWARDS General University

  20. OKLAHOMA STATE UNIVERSITY MEDICAL AUTHORITY

    E-Print Network [OSTI]

    Veiga, Pedro Manuel Barbosa

    OKLAHOMA STATE UNIVERSITY MEDICAL AUTHORITY June 30, 2010 #12;OKLAHOMA STATE UNIVERSITY MEDICAL Authority Members Oklahoma State University Medical Authority Tulsa, Oklahoma We have audited the accompanying statements of financial position of the Oklahoma State University Medical Authority (the

  1. OKLAHOMA STATE UNIVERSITY MEDICAL AUTHORITY

    E-Print Network [OSTI]

    Veiga, Pedro Manuel Barbosa

    OKLAHOMA STATE UNIVERSITY MEDICAL AUTHORITY June 30, 2009 #12;OKLAHOMA STATE UNIVERSITY MEDICAL Authority Members Oklahoma State University Medical Authority Tulsa, Oklahoma We have audited the accompanying statements of financial position of the Oklahoma State University Medical Authority (the

  2. Qubit State Discrimination

    E-Print Network [OSTI]

    M. E. Deconinck; B. M. Terhal

    2010-03-01

    We show how one can solve the problem of discriminating between qubit states. We use the quantum state discrimination duality theorem and the Bloch sphere representation of qubits which allows for an easy geometric and analytical representation of the optimal guessing strategies.

  3. United States Department of

    E-Print Network [OSTI]

    Liebhold, Andrew

    United States Department of Agriculture Forest Service Northeastern Research Station Research Paper of the Eastern United States have been devastated by invasive pests. We used existing data to predict-quarter in total host density. Gypsy moth occupies only 23 percent of its potential range in the Eastern United

  4. United States Department of

    E-Print Network [OSTI]

    United States Department of Agriculture Forest Service Pacific Southwest Forest and Range Thomas J. Mills Frederick W. Bratten #12;The Authors: are with the Station's research unit studying fire J. MILLS, a forest economist, is in charge of the unit. He earned degrees at Michigan State

  5. UNITED STATES PARTMENT OF

    E-Print Network [OSTI]

    UNITED STATES PARTMENT OF lMMERCE J8l1CATION SEATTLE, WA IOVEMBER 1973 FISHERY FACTS-6 U. S of foreign fishing off United States coastal waters, and the aevelopment and enforce- ment of international;ABSTRACT Dungeness crabs, Cancer magister, occur in the inshore waters of t he west coast of the United

  6. Iowa State University Engineering

    E-Print Network [OSTI]

    Lin, Zhiqun

    1 Iowa State University Engineering Student Clubs Engineering Student CouncilIowa State University #12;2 AirISU Pg. 4 Alpha Pi Mu Industrial Engineering Honor Society (APM) Pg. 4 American Institute of Aeronautics and Astronautics (AIAA) Pg. 5 American Society of Agricultural and Biological Engineers (ASABE) Pg

  7. Solid State Division

    SciTech Connect (OSTI)

    Green, P.H.; Watson, D.M.

    1989-08-01

    This report contains brief discussions on work done in the Solid State Division of Oak Ridge National Laboratory. The topics covered are: Theoretical Solid State Physics; Neutron scattering; Physical properties of materials; The synthesis and characterization of materials; Ion beam and laser processing; and Structure of solids and surfaces. (LSP)

  8. Hard (State) Problems

    E-Print Network [OSTI]

    John A. Tomsick

    2008-12-16

    For microquasars, the one time when these systems exhibit steady and powerful jets is when they are in the hard state. Thus, our understanding of this state is key to learning about the disk/jet connection. Recent observational and theoretical results have led to questions about whether we really understand the physical properties of this state, and even our basic picture of this state is uncertain. Here, I discuss some of the recent developments and possible problems with our understanding of this state. Overall, it appears that the strongest challenge to the standard truncated disk picture is the detection of broad iron features in the X-ray spectra, and it seems that either there is a problem with the truncated disk picture or there is a problem with the relativistic reflection models used to explain the broad iron features.

  9. Fourth generation bound states

    SciTech Connect (OSTI)

    Ishiwata, Koji; Wise, Mark B. [California Institute of Technology, Pasadena, California, 91125 (United States)

    2011-04-01

    We investigate the spectrum and wave functions of q{sup '}q{sup '} bound states for heavy fourth generation quarks (q{sup '}) that have a very small mixing with the three observed generations of standard model quarks. Such bound states come with different color, spin and flavor quantum numbers. Since the fourth generation Yukawa coupling, {lambda}{sub q}{sup '}, is large we include all perturbative corrections to the potential between the heavy quark and antiquark of order {lambda}{sub q}{sup '2}N{sub c}/16{pi}{sup 2} where N{sub c} is the number of colors, as well as relativistic corrections suppressed by (v/c){sup 2}. We find that the lightest fourth generation quark masses for which a bound state exists for color octet states. For the color singlet states, which always have a bound state, we analyze the influence that the Higgs couplings have on the size and binding energy of the bound states.

  10. United States Conservation Plan

    E-Print Network [OSTI]

    Gray, Matthew

    United States Shorebird Conservation Plan M A N O M E T C E N T E R F O R C O N S E R V A T I O N T I O N #12;United States Shorebird Conservation Plan Council Organizations #12;1 U n i t e d S t a t e s S h o r e b i r d C o n s e r v a t i o n P l a n 2 0 0 1 The United States Shorebird

  11. Michigan State University Press

    E-Print Network [OSTI]

    Liu, Taosheng

    Michigan State University Press FALL/ WINTER 2013 #12;MICHIGANSTATEUNIVERSITYPRESS This symbol MSU PRESS TITLES American Literature ........................................................... 2 .............................................................................. 7 UNIVERSITY OF CALGARY PRESS .............................. 22­24 UNIVERSITY OF MANITOBA PRESS

  12. Solid State Lighting Reliability

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Solid State Lighting Reliability 2015Building Technologies Office Peer Review Lynn Davis, PhD RTI International ldavis@rti.org --- 919-316-3325 Project Summary Timeline: Start...

  13. United States Government

    Office of Environmental Management (EM)

    States Government Department of Energy memorandum Carlsbad Field Office Carlsbad, New Mexico 88221 DATE: REPLY TO ATTN OF: SUBJECT: JAN 1 7 2014 CBFO:OESH:GTB:MN:14-1404:UFC...

  14. United States of Agriculture

    E-Print Network [OSTI]

    United States Department of Agriculture DESIGN: A Program to Create Data Forest Service Entry Research Work Unit at the Station's Forest Fire Laboratory, 4955 Canyon Crest Drive, Riverside, CA 92507

  15. United States of Agriculture

    E-Print Network [OSTI]

    United States Department of Agriculture Forest Service Pacific Southwest Research Station General Observatory in Stinson Beach, Calif. Thomas E. Martin is Assistant Unit Leader--Wildlife at the U.S. Fish

  16. United States Department of

    E-Print Network [OSTI]

    United States Department of Agriculture Forest Service Pacific Southwest Forest and Range, objectives, and targets and specific work plans for the field units--the National Forests and their Ranger

  17. United States Department of

    E-Print Network [OSTI]

    United States Department of Agriculture Forest Service Northeastern Forest Experiment Station research unit in New Hampshirein 1957, where he studied problemsof regenerationandthinning research unit at Warren, Pennsylvania, where he headed a program of research on problems related

  18. United States Department of

    E-Print Network [OSTI]

    United States Department of Agriculture Forest Service Peelflc Southwest Forest and Range that are expressed in tems familim to the user. Theboard footand cubic footare mdiriond units of measure, altlnough

  19. United States Department of

    E-Print Network [OSTI]

    #12;United States Department of Agriculture Forest Service Pacific Southwest Research Station for the Station's Wildland Recreation and the Urban Culture Research Work Unit, located at the Forest Fire

  20. Quantum Physics: Altered States 

    E-Print Network [OSTI]

    Haw, Mark

    2002-06-27

    Stand by for a new state of matter — according to some predictions, it could be created in the next few months. In a handful of laboratories around the world, physicists are trying to persuade antisocial atoms to pair ...