Growing and characterization of La 0.8Sr 0.2MnO 3 thin films on single crystal oxide substrate

Abstract

La 0.8Sr 0.2MnO 3 (LSMO) displays a transition from a low temperature metallic phase to an insulator high temperature phase. Depending on Sr concentration, the transition temperature may occur above room temperature. This property may be used for integrated microelectronic devices like limiter of current and/or voltage. The weak lattice mismatch between the LSMO and different substrates like LaAlO 3 (0 0 1) or SrTiO 3 (1 0 0) favors an epitaxial growth of LSMO deposited by pulsed laser ablation techniques. Analyses by X-ray diffraction, infrared reflectivity spectroscopy and temperature dependence of the resistivity allow the optimization of growing condition. The aim is to reach or at least to approach the crystal properties. The target was elaborated by organic gel-assisted citrate process. The X-ray diffractograms show that the films have a c-axis orientation. The film thicknesses have been deduced from the interferences observed in infrared spectra in the semi-transparent regime at high frequencies. The measurements of resistivity versus temperature show that the transition temperature reaches 325 K for optimized growing conditions. The conductivity of the film approaches that of the crystal at the transition temperature.