Abstract
We observed the microstructure of perovskite thin films, and compared the results with their colossal magnetoresistance (CMR) properties. Epitaxial or textured films of La1-xSrxMnyO3-δwere prepared by rf sputtering on (100)SrTiO3 and (110)sapphire single crystal substrates. The films were investigated by X-ray diffraction, magnetoresistance measurement, and transmission electron microscopy (TEM). The magnetoresistance of the films deposited on SrTiO3 substrate shows similar temperature dependence to that of bulk single crystals. The temperature dependence of the magnetresistance in the films on a sapphire substrate is different from that in bulk single crystals, that is, the magnetoresistance decrease monotonously with increasing temperature. We revealed by TEM observations that the films on SrTiO3 substrate grew epitaxially with a number of defects, however, the films on sapphire substrate grew with a columnar structure and showed no epitaxy. Therefore, the difference in the MR properties is attributed to the lattice mismatch between films and substrates.
