Annealing Effects of Co–Cr–Pt–SiO $_2$ Perpendicular Magnetic Recording Media

High coercivity (H c ) and magnetic anisotropy constants (K u ) can be achieved by postannealing in Co-Cr-Pt-SiO 2 /Ru perpendicular magnetic recording media without grain size growth or interdiffusion. Cr oxide formation is promoted by annealing, especially at the interface of the Ru underlayer and Co-Cr-Pt-SiO 2 layer due to oxygen depth profile. Annealing beyond a particular temperature results in grain growth of the Co alloy and enhanced exchange coupling