Thermal properties of La2/3Ba1/3(Mn1−xSbx)O3 manganites

Effects of Sb doping on thermal properties like thermoelectric power (S), thermal conductivity (κ), and specific heat (Cp) of La2/3Ba1/3(Mn1−xSbx)O3 (x=0.00–0.05) perovskite manganites are reported. It has been found that S is positive at low temperature and becomes negative at higher temperatures. A pronounced peak was observed in S at the insulator–metal transition for the pristine sample La2/3Ba1/3MnO3, which gets suppressed with Sb-doping. In addition, electron to hole-like crossover temperature seen in the S(T) is also found to move towards lower temperatures with increasing Sb content. The anomalous behavior in thermal conductivity (κ) at the transition is ascribed to the local anharmonic distortions associated with small polarons. The observed reduction of the total κ(T) due to Sb-doping is discussed with various thermal scattering mechanisms. From the specific heat results, broadening of observed sharp peak in the pristine LBMO data on substitution of Sb at Mn site was recognized as the enhancement of magnetic inhomogeneity in these manganites.