Influence of substrate temperature on magnetotransport properties of thin films of La Sr MnO 0.7 0.3 3

La0.7Sr0.3MnO3 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. q1999 Elsevier Science B.V. All rights reserved.