Microstructure-dependent magnetoresistance in La1-xMnO3 thin films

We have prepared thin La1-xMnO3 films by metal organic chemical vapour depo sition. The films were grown at deposition temperature T-D = 700 degrees C on various types of substrates; polycrystalline Al2O3, polycrystalline SrTi O3 having various grain size, and single-crystalline SrTiO3 slices. The fil ms exhibited transition to metallic state at temperatures from 200 to 260 K , depending on the substrate. Resistivity at the transition ranged from the value of 10 Ohm cm for the small grain size polycrystalline films to 100 a nd 300 m Ohm cm for the large grain size polycrystalline and epitaxial film on the SrTiO3 single-crystalline substrate, respectively. We discuss magne toresistance in the La1-xMnO3 films in correlation with their microstructur e, studied by transmission electron microscopy. (C) 2000 Elsevier Science B .V. All rights reserved.