Effect of annealing on Curie temperature and phase transition in La0.55Sr0.08Mn0.37O3 epitaxial films grown on SrTiO3 (100) substrates by reactive radio frequency magnetron sputtering

Abstract Mn-poor LaSrMnO 3 (LSMO) epitaxial films were grown on SrTiO 3 (100) substrates by radio frequency magnetron sputtering in an argon and oxygen gas mix, and then the samples were annealed in air at various temperatures ( T a ). 2 theta-chi X-ray diffraction mapping, nano-beam diffraction analysis through transmission electron microscopy, and electron back scatter diffraction through scanning electron microscopy revealed that the crystal symmetry of the LSMO films changed from monoclinic/orthorhombic to rhombohedral on annealing in air. Curie temperature ( T C ) of the LSMO films was found to increase with increasing T a , and become higher than the room temperature at T a  ≥ 861 °C, indicating that the cause of these changes was the filling of oxygen and the transition of the crystal symmetry into rhombohedral.