Magnetoresistance in LaNi1−xCoxO3 (0.3≤x≤0.6)

We report on a detailed study of the electrical resistivity and the magnetoresistance of the metallic members of the LaNi1−xCoxO3 series with 0.3≤x≤0.6. The low-temperature resistivity of the compounds with 0.3≤x≤0.5 exhibits a logarithmic temperature dependence that is characteristic of systems with enhanced spin disorder. We attribute the decreasing contribution of the −ln T term to resistivity with increasing magnetic field to the suppression of spin disorder in an electronically phase separated matrix by the application of magnetic field, and suggest that this mechanism is primarily responsible for the magnetoresistive behavior of these compounds. We propose two models that are based on inter-cluster scattering which could explain the observed effects.