Detailed relationship between local structure, polarons, and magnetization for La 1?xCa xMnO 3 (0.21≥x≥0.45)

Document Type

Article

Publication Date

5-3-2010

Abstract

We present detailed local structure measurements (using the extended x-ray absorption fine structure technique) for the colossal magnetoresistive material La 1-x Ca x MnO 3(0.21T, the slope is low and the distortion removed as the sample becomes magnetized is small-we argue this arises from polarons which have a low distortion around two (or possibly three) Mn sites. At high magnetizations large distortions per Mn site are removed as these sites become magnetized. The data are also analyzed in terms of a two Mn-O peak distribution using experimental standards for Mn-O. The results agree well with recent neutron PDF results but not with some earlier results. We discuss the limitations of assuming a two peak distribution in view of the two distortions needed to describe the Mn-O distortions as a function of T and B for B≤T. It is likely that there is a distribution of longer bonds. Finally we show that with increasing B field, the Mn-Mn peak also has a small B -field-induced change-a measure at the unit cell level of magnetostriction but find that there is no observable B -field-induced change in the Mn-La/Ca pair distribution for fields up to ∼10 T. © 2010 The American Physical Society.

Identifier

77955435467 (Scopus)

Publication Title

Physical Review B Condensed Matter and Materials Physics

External Full Text Location

https://doi.org/10.1103/PhysRevB.81.184401

e-ISSN

1550235X

ISSN

10980121

Issue

18

Volume

81

Grant

0907036

Fund Ref

National Science Foundation

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