Microstructural and electrical properties of La0.7Ca0.3MnO3 thin films grown on SrTiO3 and LaAlO3 substrates using metal-organic deposition

Abstract

La 0.7 Ca 0.3 MnO 3 (LCMO) thin films have been prepared on LaAlO3 and SrTiO3 (STO) (001) single-crystal substrates by the metal-organic deposition process. These films were characterized by transmission electron microscopy (TEM) and temperature dependence of the resistance R(T). The microstructure of the LCMO films and LCMO/substrate interfaces were investigated through cross-sectional TEM observations. High-resolution TEM (HRTEM) observations and electron-diffraction patterns demonstrate the (001) epitaxial growth on both the LAO and STO substrates. The local structure of the LCMO film depends on the type of substrate. HRTEM observations along the LCMO/STO interface display a good epitaxy throughout the entire film without any microstructural defects. On the contrary, in the LCMO film and in the region close to the LAO substrate, we note the presence of misfit dislocations and twins. The temperature coefficient of resistance (TCR) was calculated from the temperature dependence of the resistance measurements. The LCMO/LAO system exhibits a TCR value of 27.5%∕K compared with the 10%∕K measured for the LCMO/STO system.