High-potential magnetic anisotropy of CoPtCr-SiO₂ perpendicular recording media

The magnetic anisotropy of CoPtCr-SiO₂ perpendicular recording media, including higher energy terms, was studied as a function of film composition and seed layer materials. All series of CoPtCr films with various Cr content, deposited on Ru seed layers, show maximum values of total anisotropy K_u at 25-30 at%Pt. The maximum value for CoPt(Cr = 0) films reaches ~ 15 × 10⁶ erg/cm³. The addition of SiO₂ to the CoPtCr films reduces the grain K_u, however the grain K _u maintains a large value of 8 × 10⁶ erg/cm ³ even when 10at%SiO₂ is added to (Co₉₀Cr ₁₀)₈₀Pt₂₀, for instance, which indicates the high-potential thermal stability. Theoretical calculations for media designs of 400 Gbits/in₂ revealed that the ratio of the high-energy anisotropy term K_u2 to K_u1(K_u = K_u1 + K _u2) is required to be 0.2-0.35 to enhance the energy barrier for the remanent state, without a notable change in switching field. The films deposited on Ru seed layers were found to show negligibly small K_u2 values, however, the values of K_u1 and K_u2 vary significantly with the seed layer material used. K_u1 decreases almost linearly as the K_u2 value increases. It is concluded that CoPtCr films have a sufficient potential in the values of K_u1 and K_u2 for high-density perpendicular media.