Perpendicular Magnetic Anisotropy of CoOx Films Prepared by Targets Facing Type of Sputtering

CoOx thin films with perpendicular magnetic anisotropy (PMA) were prepared at room temperature by the reactive facing-target sputtering technique. We investigated the PMA, coercivity and static magnetization process of the film samples, with the following results. (1) CoOx films with a columnar structure are composed of hep Co and fcc CoO. (2) The highest perpendicular anisotropy energy Ku was 2.3×10⁶ erg/cm³. Ku increases with increasing Ms; the PMA of CoOx thin films is attributed to the magnetocrystalline anisotropy of Co. (3) Hca increases with decreasing diameter of columnar grains in CoOx thin films. (4) The dependence of Hc¿ on the direction of the applied magnetic field is similar to that expected from the Stoner-Wohlfarth model. The static magnetization process in CoOx thin films is mainly the rotational type.