Universal relationship between magnetization and changes in the local structure of La1-xCaxMnO3: evidence for magnetic dimers.
We present extensive x-ray absorption fine structure measurements on La(1-x)Ca(x)MnO(3) as a function of the B field (to 11 T) and Ca concentration, chi(21%-45%). These results reveal local structure changes (associated with polaron formation) that depend only on the magnetization for a given sample, irrespective of whether the magnetization is achieved through a decrease in temperature or an applied magnetic field. Furthermore, the relationship between local structure and magnetization depends on the hole doping. A model is proposed in which a filamentary magnetization initially develops via the aggregation of pairs of Mn atoms involving a hole and an electron site. These pairs have little distortion and it is likely that they form at temperature T(*) above T(c).
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Physics Department, University of California, Santa Cruz, 95064, USA.
Bridges
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Bushart
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Neumeier
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Dilley
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Zhou
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