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Title: Effect of oxygen isotope substitution and crystal microstructure on magnetic ordering and phase separation in (La{sub 1-y}Pr{sub y}){sub 0.7}Ca{sub 0.3}MnO{sub 3}

Abstract

The crystal and magnetic structures of the specified CMR manganite system have been studied as a function of y=(0.2-1) across the metal-insulator (MI) transition, and of the oxygen mass ({sup 16}O, {sup 18}O). We quantitatively show how the polaronic narrowing of the carrier bandwidth and the crystal lattice microstrains control the volume fractions of the mesoscopic ferromagnetic and antiferromagnetic clusters. A well-defined dip in the transition temperatures and the suppression of all the types of long range ordering seen near the MI transition at y{approx_equal}0.9 indicate a key role of the quenched disorder for the formation of the long-scale phase separated state.

Authors:
; ; ; ;  [1];  [2];  [2];  [3]
  1. Laboratory for Neutron Scattering, ETH Zurich (Switzerland) and Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland)
  2. (Switzerland)
  3. (Russian Federation)
Publication Date:
OSTI Identifier:
20976674
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. B, Condensed Matter and Materials Physics; Journal Volume: 75; Journal Issue: 5; Other Information: DOI: 10.1103/PhysRevB.75.054410; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ANTIFERROMAGNETIC MATERIALS; ANTIFERROMAGNETISM; CALCIUM COMPOUNDS; CRYSTAL LATTICES; CRYSTALS; FERROMAGNETIC MATERIALS; LANTHANUM COMPOUNDS; MAGNETIZATION; MICROSTRUCTURE; OXYGEN; OXYGEN 16; OXYGEN 18; POLARONS; PRASEODYMIUM COMPOUNDS; TRANSITION TEMPERATURE

Citation Formats

Pomjakushin, V. Yu., Sheptyakov, D. V., Conder, K., Pomjakushina, E. V., Balagurov, A. M., Laboratory for Developments and Methods, PSI, CH-5232 Villigen PSI, Laboratory for Developments and Methods, PSI, CH-5232 Villigen PSI, Switzerland and Laboratory for Neutron Scattering, ETH Zurich and Paul Scherrer Institut, CH-5232 Villigen PSI, and Frank Laboratory of Neutron Physics, JINR, 141980, Dubna. Effect of oxygen isotope substitution and crystal microstructure on magnetic ordering and phase separation in (La{sub 1-y}Pr{sub y}){sub 0.7}Ca{sub 0.3}MnO{sub 3}. United States: N. p., 2007. Web. doi:10.1103/PHYSREVB.75.054410.
Pomjakushin, V. Yu., Sheptyakov, D. V., Conder, K., Pomjakushina, E. V., Balagurov, A. M., Laboratory for Developments and Methods, PSI, CH-5232 Villigen PSI, Laboratory for Developments and Methods, PSI, CH-5232 Villigen PSI, Switzerland and Laboratory for Neutron Scattering, ETH Zurich and Paul Scherrer Institut, CH-5232 Villigen PSI, & Frank Laboratory of Neutron Physics, JINR, 141980, Dubna. Effect of oxygen isotope substitution and crystal microstructure on magnetic ordering and phase separation in (La{sub 1-y}Pr{sub y}){sub 0.7}Ca{sub 0.3}MnO{sub 3}. United States. doi:10.1103/PHYSREVB.75.054410.
Pomjakushin, V. Yu., Sheptyakov, D. V., Conder, K., Pomjakushina, E. V., Balagurov, A. M., Laboratory for Developments and Methods, PSI, CH-5232 Villigen PSI, Laboratory for Developments and Methods, PSI, CH-5232 Villigen PSI, Switzerland and Laboratory for Neutron Scattering, ETH Zurich and Paul Scherrer Institut, CH-5232 Villigen PSI, and Frank Laboratory of Neutron Physics, JINR, 141980, Dubna. Thu . "Effect of oxygen isotope substitution and crystal microstructure on magnetic ordering and phase separation in (La{sub 1-y}Pr{sub y}){sub 0.7}Ca{sub 0.3}MnO{sub 3}". United States. doi:10.1103/PHYSREVB.75.054410.
@article{osti_20976674,
title = {Effect of oxygen isotope substitution and crystal microstructure on magnetic ordering and phase separation in (La{sub 1-y}Pr{sub y}){sub 0.7}Ca{sub 0.3}MnO{sub 3}},
author = {Pomjakushin, V. Yu. and Sheptyakov, D. V. and Conder, K. and Pomjakushina, E. V. and Balagurov, A. M. and Laboratory for Developments and Methods, PSI, CH-5232 Villigen PSI and Laboratory for Developments and Methods, PSI, CH-5232 Villigen PSI, Switzerland and Laboratory for Neutron Scattering, ETH Zurich and Paul Scherrer Institut, CH-5232 Villigen PSI and Frank Laboratory of Neutron Physics, JINR, 141980, Dubna},
abstractNote = {The crystal and magnetic structures of the specified CMR manganite system have been studied as a function of y=(0.2-1) across the metal-insulator (MI) transition, and of the oxygen mass ({sup 16}O, {sup 18}O). We quantitatively show how the polaronic narrowing of the carrier bandwidth and the crystal lattice microstrains control the volume fractions of the mesoscopic ferromagnetic and antiferromagnetic clusters. A well-defined dip in the transition temperatures and the suppression of all the types of long range ordering seen near the MI transition at y{approx_equal}0.9 indicate a key role of the quenched disorder for the formation of the long-scale phase separated state.},
doi = {10.1103/PHYSREVB.75.054410},
journal = {Physical Review. B, Condensed Matter and Materials Physics},
number = 5,
volume = 75,
place = {United States},
year = {Thu Feb 01 00:00:00 EST 2007},
month = {Thu Feb 01 00:00:00 EST 2007}
}
  • We present a detailed magnetic study of the perovskite manganite Pr{sub 0.7}Ca{sub 0.3}MnO{sub 3} at low temperatures including magnetization and ac susceptibility measurements. The data appear to exclude a conventional spin glass phase at low fields, suggesting instead the presence of correlated ferromagnetic clusters embedded in a charge-ordered matrix. We examine the growth of the ferromagnetic clusters with increasing magnetic field as they expand to occupy almost the entire sample at H{approx}0.5T. Since this is well below the field required to induce a metallic state, our results point to the existence of a field-induced ferromagnetic insulating state in this material.
  • We prepared orthorhombic La{sub 0.7−x}Y{sub x}Ca{sub 0.3}MnO{sub 3} samples (x = 0, 0.04, 0.06, and 0.08) by conventional solid-state reaction and then studied their magnetic properties and magnetocaloric (MC) effect based on magnetization versus temperature and magnetic-field measurements, M(T, H). The experimental results revealed that an x increase in La{sub 0.7−x}Y{sub x}Ca{sub 0.3}MnO{sub 3} reduced the ferromagnetic-paramagnetic transition temperature (T{sub C}) from 260 K (for x = 0) to ∼126 K (for x = 0.08). Around the T{sub C}, maximum magnetic-entropy changes for a magnetic-field variation interval H = 50 kOe are about 10.7, 8.5, 7.4, and 5.8 J·kg{sup −1}·K{sup −1} for x = 0, 0.04, 0.06, and 0.08, respectively, corresponding to refrigerantmore » capacities RC = 250–280 J·kg{sup −1}. These values are comparable to those of some conventional MC materials, revealing the applicability of La{sub 0.7−x}Y{sub x}Ca{sub 0.3}MnO{sub 3} in magnetic refrigeration. Using the Arrott method and scaling hypothesis as analyzing high-field M(H, T) data, and the universal-curve construction of the magnetic entropy change, we found a magnetic-phase separation. While the samples x = 0−0.06 exhibit a first-order magnetic phase transition, x = 0.08 exhibits the crossover of the first-to-second-order phase transformation (with its critical-exponent values close to those expected for the tricritical mean-field theory) and has the presence of ferromagnetic clusters even above the T{sub C}. Such the variations in the magnetism and MC effect are related to the changes in structural parameters caused by the Y substitution for La because Y doping does not change the concentration ratio of Mn{sup 3+}/Mn{sup 4+}.« less
  • We report a memory concept utilizing ferromagnet/superconductor/ferromagnet La{sub 0.7}Ca{sub 0.3}MnO{sub 3}/YBa{sub 2}Cu{sub 3}O{sub 7}/La{sub 0.7}Ca{sub 0.3}MnO{sub 3} thin film hybrid structures. The orientation of the magnetic field with respect to the ferromagnetic easy axis has a strong effect on superconductivity as indicated by a strong variation in the magnetoresistance (MR). MR can be controlled by rotating a small magnetic field applied in the plane of the film in a way that is determined by the in-plane biaxial magnetic anisotropy. The proposed memory device has the advantages of superconducting detection elements (fast response and low dissipation), small (100-150 Oe) writing fields,more » and resistance read-out without need for applied field.« less
  • Thin films of La{sub 5/8−y}Pr{sub y}Ca{sub 3/8}MnO{sub 3} (y≈0.4) have been grown on single crystal SrTiO{sub 3} (001) by RF sputtering. The structural and surface characterizations confirm the epitaxial nature of these film. However, the difference between the ω-scan of the (002) and (110) peaks and the presence of pits/holes in the step-terrace type surface morphology suggests high density of defect in these films. Pronounced hysteresis between the field cooled cooling (FCC) and field cooled warming (FCW) magnetization measurements suggest towards the non-ergodic magnetic state. The origin of this nonergodicity could be traced to the magnetic liquid like state arisingmore » from the delicacy of the coexisting magnetic phases, viz., ferromagnetic and antiferromagnetic-charge ordered (FM/AFM-CO). The large difference between the insulator metal transitions during cooling and warming cycles (T{sub IM}{sup C} ∼ 64 K and T{sub IM}{sup W} ∼ 123 K) could be regarded as a manifestation of the nonergodicity leading to supercooling of the magnetic liquid while cooling. The nonergodicity and supercooling are weakened by the AFM-FM phase transition induced by an external magnetic field. T{sub IM} and small polaron activation energy corresponding the magnetic liquid state (cooling cycle) vary nonlinearly with the applied magnetic field but become linear in the crystalline solid state (warming cycle). The analysis of the low temperature resistivity data shows that electron-phonon interaction is drastically reduced by the applied magnetic field. The resistivity minimum in the lower temperature region of the self-field warming curve has been explained in terms of the Kondo like scattering in the magnetically inhomogeneous regime.« less
  • We have studied the magneto-transport and magnetic properties of LSMO/YBCO/LSMO trilayers on LaAlO{sub 3} (001) substrate, deposited using pulsed laser deposition technique. From x-ray diffraction measurements, it is confirmed that the grown trilayer films are single phase natured. The temperature dependent resistivity shows a metallic behavior below 350 K. At low temperature from resistivity fitted data, we observe that electron-electron, electron-phonon, and electron-magnon interactions are the main factors for scattering of carriers. The ferromagnetic LSMO layers suppress the critical temperature of YBCO spacer layer. We observe maximum magnetoresistance value ∼49% at 250 K for LSMO(200 nm)/YBCO(50 nm)/LSMO(200 nm) trilayer. Magnetization measurements reveal that at roommore » temperature the YBCO spacer layer is allowing the LSMO layers to interact antiferromagnetically.« less