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

Journal Article · Sun Dec 01 04:00:00 EST 1996 · Physical Review, B: Condensed Matter

DOI:https://doi.org/10.1103/PhysRevB.54.R15606· OSTI ID:399843

Booth, C H; Bridges, F ^[1]; Snyder, G J; Geballe, T H ^[2]

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1. Department of Physics, University of California, Santa Cruz, California 95064 (United States)
2. 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

Related Subjects

36 MATERIALS SCIENCE
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