Effects of preferred orientation on electrical properties of Mn1.56Co0.96Ni0.48O4±δ spinel films

Mn1.56Co0.96Ni0.48O4±δ thin films are fabricated by Pulsed Laser Deposition process at different oxygen partial pressure. The X-ray diffraction shows that the preferential orientation of the films changes from (4 0 0) plane to (1 1 3) as the oxygen pressure increases. The resistance of the (1 1 3)-oriented films is found to decrease compared to those of the (4 0 0)-oriented ones. Meanwhile, the activation energy Ea increases dramatically. A detailed X-ray photoemission spectroscopy study of the lattice oxygen content and Mn cation distribution is performed. The results reveal that higher oxygen partial pressure during deposition should be responsible for the preferred (1 1 3) plane growth and the greatly elevated amount of Mn3+ and Mn4+, which can result in significantly different electrical properties of Mn1.56Co0.96Ni0.48O4±δ spinel films.