Temperature dependence of non-Debye disorder in doped manganites

Abstract

Ca-doped manganite ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}$MnO${}_{3}$ samples with $x$=0.2 and 0.4 were investigated by extended x-ray absorption fine structure (EXAFS) as a function of temperature and preparation method. The samples exhibit characteristic resistivity change across the metal-insulator (MI) transition temperature whose shape and position depend on Ca-doping concentration and sample thermal treatment. EXAFS results evidenced an increase of nonthermal disorder at the MI transition temperature which is significantly correlated with the resistivity behavior.