Effect of oxygen nonstoichiometry on electrotransport and low-field magnetotransport property of polycrystalline La0.5Sr0.5MnO3-δ thin films

Abstract

Polycrystalline La0.5Sr0.5MnO3-δ thin films deposited on quartz wafers at 680°C and various oxygen pressures P by pulsed laser deposition are prepared. The effects of oxygen nonstoichiometry on the microstructural, electrotransport and low-field magnetotransport property of the thin films are investigated in details. A structural distortion from the stoichiometric lattice is identified for the samples deposited at P 0.1 mbar. Oxygen overdeficiency at P≤0.1 mbar essentially prohibits the spin reordering. The temperature dependence of the electro- and magnetotransport properties is explained by the two-channel model where the insulating channels and metallic ones coexist in parallel.