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