The effect of oxygen partial pressure on the electron-magnetic properties of La0.67Sr0.33MnO3-δ epitaxial films with different orientations

Crystalline structure, electronic transport and magnetic properties were systematically studied for La0.67Sr0.33MnO3-delta epitaxial films fabricated through direct current magnetron sputtering method on LaAlO3 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 (111), (001), and (110) orientations, respectively. As P increases to 9 Pa, Tp changes to 177.27, 235.65 and 259.78 K for (111), (110) and (001) 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 Mn3+ to Mn4+ ions in the films prepared under different oxygen partial pressures. (C) 2002 Elsevier Science B.V. All rights reserved.