Preparation of Co Ferrite Thin Films for Magnetic Recording Media by the Ferrite-Plating Method

Abstract

Perpendicular anisotropic Co_xFe_3-xO₄ films 25-200 nm in thickness for perpendicular magnetic recording media were successfully obtained by the spin-spray ferrite-plating method at 90°C. The perpendicular coercivity H_c⊥of the films took a maximum at around 0.5, and the value of H_c⊥ was over 2000 Oe even for a film thickness of 25 nm. By optimizing the concentration of NaNO₂ in the oxidizing solution, the in-plane coercivity H_c// was reduced to 300 Oe, while H_c⊥ was kept at over 2000 Oe. Mössbauer analyses show that the films have excellent perpendicular magnetic anisotropy. The angular dependence of the coercivity shows that a reversal of the magnetization takes place in the rotation mode as in Co-Cr sputter-deposited films.