Epitaxial growth and magnetic/transport properties of La0.7Sr0.3MnO3 thin films grown on SrTiO3 with optimized growth conditions

Abstract

Epitaxial growth of colossal magnetoresistive thin films of La_0.7Sr_0.3MnO₃ (LSMO) has been achieved on TiO₂-terminated (001) SrTiO₃ (STO) single-crystal substrates using PLD (pulsed laser deposition). The temperature dependence of film magnetization and resistance was measured and the characteristics of film surface roughness were studied. Effects of oxygen partial pressure and substrate temperature on the surface topography, Curie temperature (T_C) and metal–insulator transitions (T_MI) were also investigated. It has been found that oxygen partial pressure has more influence on the Curie temperature but less on the surface topography than the substrate temperature does. Meanwhile, at high oxygen partial pressures, Curie temperatures of sample films were affected insignificantly by the substrate temperature, while the surface morphology was affected remarkably. The influence of the substrate temperature on the T_MI is similar to that of the Curie temperature. Finally, thin films were successfully grown with bulk-like Curie temperature of about 360 K, and a relatively high magnetization of about 1.6 ± 0.11 μ_B per Mn atom at room temperature was achieved. The surface roughness of these thin films is about 350 pm, which is close to the thickness of a layer of cells. The high quality of LSMO films was confirmed by a 10 h retention test of ultra-thin BaTiO₃ (BTO) films grown on La_0.7Sr_0.3MnO₃.