Electrical and magnetic properties of La0.5Sr0.5CoO3 thin films

Highly conductive perovskite La0.5Sr0.5CoO3 thin films were grown on (012) LaAlO3 by pulsed-laser deposition at different substrate temperatures. Magnetoresistance (MR) measurements show only a negative effect for the films grown at a temperature of 800 degrees C. However, a positive MR effect was found for the films grown at lower temperatures of 400 and 500 degrees C. The sign of the magnetoresistance changed from positive to negative near 150 K under an applied magnetic field of 5.0 T, and the largest positive MR of 2.6% was obtained at a temperature of 4.2 K for the film grown at 500 degrees C. Low-temperature magnetic hysteresis of the films was also studied, and it is suggested that the scattering of the carrier at the domain boundary may lead to the positive-MR effect. (C) 2000 American Institute of Physics. [S0003-6951(00)02314-7].