Fabrication and magnetic properties of metal/cobalt ferrite composite thin films

Abstract

To improve the saturation magnetization (M(s)) of cobalt ferrite thin films, metal/cobalt ferrite composite thin films were prepared by controlling the sputtering conditions such as oxygen concentration in sputtering gas, substrate temperature, composition of the thin films. With decreasing the oxygen ratio from 50% to 5% in sputtering gas and increasing the substrate temperature from room temperature to 400 degrees C, the M(s) of the thin films was increased and the coercivity (H-c) decreased. The result was attributed to deposition of the metal/cobalt ferrite thin films. With increasing the metal ratio in the thin films, preferred orientation of (111) of cobalt ferrite was worsened in the thin films. The metal deposited in the thin films was identified as cobalt with (002) preferred orientation. In higher cobalt content than the stoichiometric composition of CoFe2O4, the thin films with high M(s) and H-c could be deposited in the wide substrate temperature range of 200-400 degrees C. We can prepare the metal/cobalt ferrite composite thin films with M(s) about 580 emu/cm(3) and H-c 1700 Oe by controlled the sputtering conditions. The thin films are thought to be applicable to the magnetic recording media with high recording density. (C) 1996 American Institute of Physics.