Abstract
We investigate the effect of Sb5+ doping at Mn-site in La0.67Ba0.33Mn1-xSbxO3 (LBMO-Sb-x) on the magnetic and magneto-electrical properties. The variation of the magnetization M versus temperature T, under an applied magnetic field of 0.05 T, reveals a ferromagnetic-paramagnetic transition for all samples. The resistivity and magneto-transport measurements are performed using standard four-probe assembly with and without magnetic fields. The temperature dependence of electrical resistivity shows that all samples undergo a sharp metal-semiconductor (M-SC) transition at a temperature (TM-SC), accompanying the ferromagnetic-paramagnetic transition. The peak resistivity rho(max) is noted at the metal-semiconductor transition temperature (TM-SC) and lowering in TM-SC is observed for higher concentrations of Sb5+. The resistivity data have been analyzed in two parts. Firstly, in the metallic region below TM-SC the resistivity data is fitted with three degree polynomial. Secondly, in the semiconducting region above TM-SC data have been fitted with Small Polaron Hopping models. Above all, the magnetoresistance study showed a peak which has a high value around the M-SC transition temperature. The dependence of resistivity on the temperature and magnetic field data is used to deduce the magnetic entropy change.