Co ferrite films with excellent perpendicular magnetic anisotropy and high coercivity deposited at low temperature

Abstract

The present article describes CoxFe3−xO4 films, which were fabricated at 90 °C by the ferrite-plating method and have the excellent perpendicular magnetic anisotropy and the perpendicular coercivity Hc⊥ above 2 kOe. The films were composed of Co ferrite and Fe3O4 grains. The highest Hc⊥ reached 3 kOe at the composition of Co0.43Fe2.57O4 and the saturation magnetization Ms was 500–550 emu/cc. Hc⊥ was over 2 kOe even for a film thickness of 35 nm without any underlayers. ΔM⊥ evaluation that is measured in the perpendicular direction to the film plane showed that the interactions in the films supported the magnetized state, stabilizing the direct current remanent state. The Mössbauer analyses revealed that the Co0.43Fe2.57O4 films have excellent perpendicular magnetic anisotropy and the magnetization direction inclined from the perpendicular axis due to the demagnetization field. This achievement will open the way to develop the high-density perpendicular recording media even when plastic disks and sheets are used as substrates.