The effect of oxygen partial pressure on the electron–magnetic properties of La 0.67Sr 0.33MnO 3− δ epitaxial films with different orientations

Abstract

Crystalline structure, electronic transport and magnetic properties were systematically studied for La 0.67Sr 0.33MnO 3− δ epitaxial films fabricated through direct current magnetron sputtering method on LaAlO 3 single crystal substrates with different orientations and sputtering pressures ( P). It is shown that the physical properties strongly depend on the orientation of substrates and oxygen partial pressure. For P=5 Pa, T p below which the transition to metallic state occurs, shows to be 112.55, 173 and 220 K for (1 1 1), (0 0 1), and (1 1 0) orientations, respectively. As P increases to 9 Pa, T p changes to 177.27, 235.65 and 259.78 K for (1 1 1), (1 1 0) and (0 0 1) orientations, respectively. A spin glass-like behavior is observed and the freezing temperature varies with P. The observed phenomena may be discussed by considering the different ratio of Mn 3+ to Mn 4+ ions in the films prepared under different oxygen partial pressures.