Capping C layer effects on magnetic properties and microstructure of FePt/MoC/CrRu films

High magnetocrystalline anisotropy (Ku) material was required for future heat assisted magnetic recording media. The ordered L1₀ FePt film can be prepared to have high [001] texture which shows high perpendicular magnetic anisotropy. Epitaxial growth of FePt films on MoC/CrRu/glass have been proved to promote chemical ordering and texturing. Dual-segregants such as transition metal-oxide with carbon have been used to obtain FePt granular structure and columnar grains. In this study, the magnetic properties and microstructure of FePt(MoC, C) films were discussed and the segregant materials were MoC and C. The Mo₄₀C₆₀ was co-sputtered with FePt and the carbon was diffused from the MoC intermediate layer. The MoC phase is formed at equal atomic ratio or higher C concentration. The Mo₅₀C₅₀ film with equal atomic ratio has been studied previously and chemical composition of Mo₄₀C₆₀ film was discussed in this study. When the atomic concentration of C is above 50%, the MoC and C phases are co-existed. The excess C was used as one of the segregant to diffuse up to separate FePt grains from intermediate layer.