Evidence of magnetization-dependent polaron distortion in La{sub 1{minus}{ital x}}{ital A}{sub {ital x}}MnO{sub 3}, {ital A}=Ca, Pb
- Department of Physics, University of California, Santa Cruz, California 95064 (United States)
- Department of Applied Physics, Stanford University, Stanford, California 94305 (United States)
X-ray-absorption fine-structure measurements at the Mn {ital K} edge as a function of temperature were performed on La{sub 1{minus}{ital x}}Ca{sub {ital x}}MnO{sub 3} and La{sub 0.67}Pb{sub 0.33}MnO{sub 3}. All samples have a metal-insulator (MI) transition near the ferromagnetic transition, except the Ca{sub 0.5} sample, which does not have a MI transition. Near {ital T}{sub {ital c}} for the samples exhibiting a MI transition, the Debye-Waller {sigma}{sup 2} for the Mn-O and Mn-Mn atom pairs increases rapidly with temperature. Since the change in {sigma}{sup 2} for the Ca/La atoms is much smaller, this nonthermal disorder must involve mainly the Mn and O atoms. These results strongly suggest that small polarons delocalize as the magnetization increases in materials which exhibit a MI transition. {copyright} {ital 1996 The American Physical Society.}
- OSTI ID:
- 399843
- Journal Information:
- Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 22 Vol. 54; ISSN PRBMDO; ISSN 0163-1829
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CALCIUM OXIDES
CURIE POINT
DEBYE-WALLER FACTOR
LANTHANUM OXIDES
LEAD OXIDES
MAGNETIC MATERIALS
MANGANESE OXIDES
METAL-INSULATOR TRANSFORMATIONS
PHASE STUDIES
POLARONS
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0273-0400 K
TRANSITION TEMPERATURE
X-RAY SPECTRA