Insulator-metal transitions, giant magnetoresistance, and related aspects of the cation-deficient LaMnO₃ compositions La_1−δMnO₃ and LaMn_1−δ'O₃

Abstract

Electron transport and magnetic properties of the cation-deficient compositions of LaMnO₃ with the nominal formulae La_1−δMnO₃(0.0≤δ≤0.2) and LaM_1−δ'O₃(0.0≤δ'≤0.2) were investigated after their defect structures were examined. La_1−δMnO₃(δ=0.1) contains more than one defect structure involving both La and Mn vacancies. La_1−δMnO₃(0.0≤δ≤0.2) compositions are all ferromagnetic and show insulator-metal (I-M) transition, with the resistivity decreasing with increasing δ. LaMn_1−δ'O₃compositions show ferromagnetism and the I-M transition only up to δ'=0.05, with the resistivity increasing with δ'. All compositions showing the I-M transitions exhibit giant magnetoresistance.