Influence of Al 2O 3 on low-temperature resistivity minima in (1 − x)La 0.7Ca 0.3MnO 3 + xAl 2O 3 composites

Abstract

The unusual low-temperature resistivity upturn of composites (1 − x)La 0.7Ca 0.3MnO 3 + xAl 2O 3 (LCMO/Al 2O 3) is presented in this paper. The depth of the resistance minima was found to increase with an increased Al 2O 3 content. We have fitted the resistivity versus temperature data from 5 to 50 K for all samples by an expression containing three terms, namely, inelastic scattering, and electron–electron (e–e) interaction and Kondo effects. We conclude that the e–e interaction effect is the dominant mechanism of LCMO/Al 2O 3 composites at low-temperature.