Co-Pt multilayers perpendicular magnetic recording media with thin Pt layer and high perpendicular anisotropy

It was found that Co-Pt multilayer films had high perpendicular magnetic anisotropy when the thickness of the Co layer was greater than that of Pt. Hc increased with decreasing Pt layer thickness and had a maximum at 0.13 nm for samples of Pt underlayer/[Co(0.44 nm)/Pt(0 ∼ 1.2 nm)]₂₀ deposited by sputtering at 4 Pa Ar gas pressure. K_⊥ also increased with decreasing Pt layer thickness, 3 × 10⁶ to 10 × 10⁶ erg/cm³. Hc increased with Co-Pt multilayer deposition Ar gas pressure, and α(dM/dH_{at Hc}) decreased with Pt underlayer deposition Ar gas pressure. By increasing deposition pressures of Co-Pt multilayers and Pt underlayer to 7.5 Pa, the characteristics of Hc: 4.7 kOe, S: 0.96, α: 4, and K_⊥: 10 × 10⁶ erg/cm³ were obtained. By inserting FeTaC soft magnetic layers between the glass substrate and Pt underlayer, Hc: 5.8 kOe, S: 0.87, and α: 1.8 were obtained. These characteristics imply that Co-Pt multilayers with thin Pt layers have potential for perpendicular magnetic recording media at high recording density because of the high K_⊥ and thin recording layer (less than 10 nm).