Study of colossal magnetoresistance material La–Sn–Mn–O epitaxial films

La–Sn–Mn–O (LSMO) thin films have been first epitaxially grown on (100) LaAlO3 single-crystal substrates by pulsed laser deposition (PLD). X-ray diffraction analyses showed that the structure of the film was perovskitelike with a uniaxial orientation. The temperature dependence of resistivity showed that an insulator-metal transition took place at the temperature Tp, which was a function of the film thickness and the tin concentration. The calculated magnetoresistance ratio MR% indicates that the maximum MR%max is as high as 103% at 6 Tesla and 233 K, and there still exist 60% values of MR% at room temperature and 6 Tesla. All these results reveal that the present film is a novel colossal magnetoresistance material with the potential in the technological applications. The investigation of the magnetic properties indicated that the Curie temperature Tc systematically varied with the tin concentration. At low temperatures, the samples were spin-glass-like with the freezing temperature affected by the film thickness and the tin concentration. The study of the electronic structure showed that the tin concentration had significant influence on the core level and structure of valence electron distribution.