Microstructure-dependent magnetoresistance in La sub(1-x)MnO sub(3) thin films

We have prepared thin La sub(1-x)MnO sub(3) films by metal organic chemical vapour deposition. The films were grown at deposition temperature T sub(D) identical with 700 degree C on various types of substrates; polycrystalline Al sub(2)O sub(3), polycrystalline SrTiO sub(3) having various grain size, and single-crystalline SrTiO sub(3) slices. The films 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 Omega cm for the small grain size polycrystalline films to 100 and 300 m Omega cm for the large grain size polycrystalline and epitaxial film on the SrTiO sub(3) single-crystalline substrate, respectively. We discuss magnetoresistance in the La sub(1-x)MnO sub(3) films in correlation with their microstructure, studied by transmission electron microscopy.