Selective mass enhancement close to the quantum critical point in BaFe _{2}(As _{1x}P _{x}) _{2}
Abstract
A quantum critical point (QCP) is currently being conjectured for the BaFe _{2}(As _{1x}P _{x}) _{2} system at the critical value x _{c} ≈ 0.3. In the proximity of a QCP, all thermodynamic and transport properties are expected to scale with a single characteristic energy, given by the quantum fluctuations. Such a universal behavior has not, however, been found in the superconducting upper critical field H _{c2}. Here we report H _{c2} data for epitaxial thin films extracted from the electrical resistance measured in very high magnetic fields up to 67 Tesla. Using a multiband analysis we find that H _{c2} is sensitive to the QCP, implying a significant charge carrier effective mass enhancement at the dopinginduced QCP that is essentially banddependent. Our results point to two qualitatively different groups of electrons in BaFe _{2}(As _{1x}P _{x}) _{2}. The first one (possibly associated to hot spots or whole Fermi sheets) has a strong mass enhancement at the QCP, and the second one is insensitive to the QCP. The observed duality could also be present in many other quantum critical systems.
 Authors:
 Dresden Univ. of Technology (Germany); Leibniz Inst. for Solid State and Materials Research (IFW), Dresden (Germany)
 Leibniz Inst. for Solid State and Materials Research (IFW), Dresden (Germany)
 Lomonosov Moscow State Univ. (Russian Federation)
 Leibniz Inst. for Solid State and Materials Research (IFW), Dresden (Germany); Lomonosov Moscow State Univ. (Russian Federation)
 Leibniz Inst. for Solid State and Materials Research (IFW), Dresden (Germany); Karlsruhe Inst. of Technology (KIT) (Germany)
 HelmholtzZentrum DresdenRossendorf, Dresden (Germany)
 Florida State Univ., Tallahassee, FL (United States)
 Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
 Tokyo Univ. of Agriculture and Technology (Japan)
 Nagoya Univ. (Japan)
 Publication Date:
 Research Org.:
 Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
 Sponsoring Org.:
 USDOE Office of Science (SC). Basic Energy Sciences (BES) (SC22)
 OSTI Identifier:
 1396128
 Report Number(s):
 LAUR1723671
Journal ID: ISSN 20452322
 Grant/Contract Number:
 AC5206NA25396
 Resource Type:
 Journal Article: Accepted Manuscript
 Journal Name:
 Scientific Reports
 Additional Journal Information:
 Journal Volume: 7; Journal Issue: 1; Journal ID: ISSN 20452322
 Publisher:
 Nature Publishing Group
 Country of Publication:
 United States
 Language:
 English
 Subject:
 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; High Magnetic Field Science; Superconductor Pnictides quantum critical point
Citation Formats
Grinenko, V., Iida, K., Kurth, F., Efremov, D. V., Drechsler, S. L., Cherniavskii, I., Morozov, I., Hänisch, J., Förster, T., Tarantini, C., Jaroszynski, J., Maiorov, B., Jaime, M., Yamamoto, A., Nakamura, I., Fujimoto, R., Hatano, T., Ikuta, H., and Hühne, R. Selective mass enhancement close to the quantum critical point in BaFe2(As1xPx)2. United States: N. p., 2017.
Web. doi:10.1038/s41598017047243.
Grinenko, V., Iida, K., Kurth, F., Efremov, D. V., Drechsler, S. L., Cherniavskii, I., Morozov, I., Hänisch, J., Förster, T., Tarantini, C., Jaroszynski, J., Maiorov, B., Jaime, M., Yamamoto, A., Nakamura, I., Fujimoto, R., Hatano, T., Ikuta, H., & Hühne, R. Selective mass enhancement close to the quantum critical point in BaFe2(As1xPx)2. United States. doi:10.1038/s41598017047243.
Grinenko, V., Iida, K., Kurth, F., Efremov, D. V., Drechsler, S. L., Cherniavskii, I., Morozov, I., Hänisch, J., Förster, T., Tarantini, C., Jaroszynski, J., Maiorov, B., Jaime, M., Yamamoto, A., Nakamura, I., Fujimoto, R., Hatano, T., Ikuta, H., and Hühne, R. Tue .
"Selective mass enhancement close to the quantum critical point in BaFe2(As1xPx)2". United States.
doi:10.1038/s41598017047243. https://www.osti.gov/servlets/purl/1396128.
@article{osti_1396128,
title = {Selective mass enhancement close to the quantum critical point in BaFe2(As1xPx)2},
author = {Grinenko, V. and Iida, K. and Kurth, F. and Efremov, D. V. and Drechsler, S. L. and Cherniavskii, I. and Morozov, I. and Hänisch, J. and Förster, T. and Tarantini, C. and Jaroszynski, J. and Maiorov, B. and Jaime, M. and Yamamoto, A. and Nakamura, I. and Fujimoto, R. and Hatano, T. and Ikuta, H. and Hühne, R.},
abstractNote = {A quantum critical point (QCP) is currently being conjectured for the BaFe2(As1xPx)2 system at the critical value xc ≈ 0.3. In the proximity of a QCP, all thermodynamic and transport properties are expected to scale with a single characteristic energy, given by the quantum fluctuations. Such a universal behavior has not, however, been found in the superconducting upper critical field Hc2. Here we report Hc2 data for epitaxial thin films extracted from the electrical resistance measured in very high magnetic fields up to 67 Tesla. Using a multiband analysis we find that Hc2 is sensitive to the QCP, implying a significant charge carrier effective mass enhancement at the dopinginduced QCP that is essentially banddependent. Our results point to two qualitatively different groups of electrons in BaFe2(As1xPx)2. The first one (possibly associated to hot spots or whole Fermi sheets) has a strong mass enhancement at the QCP, and the second one is insensitive to the QCP. The observed duality could also be present in many other quantum critical systems.},
doi = {10.1038/s41598017047243},
journal = {Scientific Reports},
number = 1,
volume = 7,
place = {United States},
year = {Tue Jul 04 00:00:00 EDT 2017},
month = {Tue Jul 04 00:00:00 EDT 2017}
}

In contrast to classical phase transitions driven by temperature, a quantum critical point (QCP) defines a transition at zero temperature that is driven by nonthermal parameters. In the known quantum critical delectron systems, tuning the electronic bandwidth by means of changing the applied pressure or unitcell dimensions, or tuning the dstate population, is used to drive the criticality. Here we describe how a novel chemical parameter, the breaking of bonds in GeGe dimers that occurs within the intermetallic framework in SrCo{sub 2}(Ge{sub 1x}P{sub x}){sub 2}, results in the appearance of a ferromagnetic (FM) QCP. Although both SrCo{sub 2}P{sub 2} andmore »

J{sub 1}J{sub 2} Heisenberg model at and close to its z=4 quantum critical point
We study the frustrated J{sub 1}J{sub 2} Heisenberg model with ferromagnetic nearestneighbor coupling J{sub 1}<0 and antiferromagnetic nextnearestneighbor coupling J{sub 2}>0 at and close to the z=4 quantum critical point (QCP) at J{sub 1}/J{sub 2}=4. The J{sub 1}J{sub 2} model plays an important role for recently synthesized chain cuprates as well as in supersymmetric YangMills theories. We study the thermodynamic properties using field theory, a modified spinwave theory, as well as numerical densitymatrix renormalization group calculations. Furthermore, we compare with results for the classical model obtained by analytical methods and Monte Carlo simulations. As one of our main results, wemore » 
Structural and magnetic phase transitions near optimal superconductivity in BaFe _{2}(As _{1x}P _{x}) _{2}
In this study, we use nuclear magnetic resonance (NMR), highresolution xray and neutron scattering to study structural and magnetic phase transitions in phosphorusdoped BaFe _{2}(As _{1x}P _{x}) _{2}. Thus, previous transport, NMR, specific heat, and magnetic penetration depth measurements have provided compelling evidence for the presence of a quantum critical point (QCP) near optimal superconductivity at x = 0.3. However, we show that the tetragonaltoorthorhombic structural (T _{s}) and paramagnetic to antiferromagnetic (AF, T _{N}) transitions in BaFe _{2}(As _{1x}P _{x}) _{2} are always coupled and approach to T _{N} ≈ T _{s} ≥ T _{c} (≈ 29 K) formore »Cited by 22 
NMR evidence for inhomogeneous nematic fluctuations in BaFe _{2}(As _{1x}P _{x}) _{2}
We present evidence for nuclear spinlattice relaxation driven by glassy nematic fluctuations in isovalent Pdoped BaFe _{2}As _{2} single crystals. Both the ^{75}As and ^{31}P sites exhibit a stretchedexponential relaxation similar to the electrondoped systems. By comparing the hyperfine fields and the relaxation rates at these sites we find that the As relaxation cannot be explained solely in terms of magnetic spin fluctuations. We demonstrate that nematic fluctuations couple to the As nuclear quadrupolar moment and can explain the excess relaxation. Lastly, these results suggest that glassy nematic dynamics are a common phenomenon in the ironbased superconductors.Cited by 8