Transport behavior of yttrium substituted polycrystalline La0.7Pb0.3MnO3

Abstract The transport properties in La0.7−xYxPb0.3MnO3 (0.0 ⩽ x ⩽ 0.2) is investigated. The substitution of La3+ ions by smaller nonmagnetic Y3+ leads to greater spin disorder and induces variations in the magnetotransport behavior. From resistivity versus temperature curves a metal–insulator transition phenomenon is observed at the transition temperature, TP, decreases as the Y content increases. The resistivity is well fitted using the equation ρ(T) = ρnexp[(T∗/T)n] with n = 1/4 and n = 1/2 at high and intermediate temperatures, respectively. The characteristic temperature T∗ varies with Y content in a manner consistent with the localization model of variable range hopping. Below TP, resistivity varies as a function of power law contributions, ρ = ρ0 + ρ2T2 + ρ5/2T5/2, corresponding to the electron scattering processes in the ferromagnetic phase.