A SPECIAL ELECTRICAL TRANSPORT BEHAVIOR IN La0.67Sr0.33MnO3/CeO2 COMPOSITES

摘要

The composites with the nominal composition of (1 - x)La0.67Sr0.33MnO3 (LSMO)/xCeO(2) were fabricated by the sol-gel method. A special electrical transport behavior is observed in the rho/rho(Tp) versus temperature curves, where rho(Tp) is the peak resistivity at the insulator-metal transition temperature (T-p). The curves for all samples with different CeO2 content are parallel in the high-T insulator regime and in a certain temperature range below T-p. Furthermore, a series of parallel straight lines can be found in the root-ln(rho/rho(Tp)) versus temperature curves for the samples with different CeO2 content. By considering the surface magnetization at the grain boundary, we obtain a simple expression for the temperature dependence of resistivity that can reproduce the experimental data in the high-T insulator regime and in a certain temperature range below T-p.