Characterization of Metal / Cobalt Ferrite Magnetic Thin Films

Metal/cobalt ferrite composite thin films with the saturation magnetization (Ms) of ~580 emu/㎤ and the coercivity (Hc) of 1700 Oe were prepared by the reactive sputtering. With increasing substrate temperature, Ms of the thin films increased, while Hc of the thin films decreased. This is attributed to the precipitation of COxFe_(1-x) (x?0.62) metal phase in the thin films. The metal phase showed the BCC structure (a_0=2.89 Å) and Im3m space group. Also, the cobalt ferrite phase was identified as CoFe₂O₄ with a cubic structure (a_0=8.39 Å) and a space group of Fd3m. For the higher cobalt content than the stoichiometric composition, Co_(37.8)Fe_(62.2), the thin films with high Ms and Hc could be obtained in the wide substrate temperature range (200-400℃).