Influence of substrate temperature on magnetotransport properties of thin films of La0.7Sr0.3MnO3

Abstract La 0.7 Sr 0.3 MnO 3 thin films have been synthesised on MgO (001) substrates using the pulsed laser deposition method. Polycrystalline or epitaxial films are obtained depending on the substrate temperature. Epitaxial films show magnetic and magnetotransport properties similar to those of single crystals. The main contribution to resistivity of polycrystalline films is due to intergrain conduction. They show an extra low field magnetoresistance regime, which, contrary to the usual colossal magnetoresistance, varies on the coercive field scale (mT). Its temperature dependence is discussed within the framework of spin dependent tunneling and half metallic ferromagnets.