CoPtCr-SiO2 perpendicular media for high density recording with a high order magnetic anisotropy energy term

The first and second order energy terms of uniaxial magnetic anisotropy, K_u1 and K_u2, of CoPtCr-SiO₂ perpendicular recording media were studied as a function of film composition and film structure. Moreover, the fabrication of CoPtCr-SiO₂ media having adequate values of K_u1 and K_u2 for high recording density was preliminarily studied. An analysis of CoPtCr films with various kinds of seed layer materials revealed that the values of K_u1 and K_u2 varied significantly with the seed layer material used, probably due to epitaxial growth of CoPtCr on the seed layers. K_u2 increased, accompanied by a reduction in K_u1 as the c/a ratio of the hcp-CoPtCr lattice increased. Moreover, experimental results suggest that a high stacking-fault density enhances the K_u2 values, especially in the high Pt content region. The addition of SiO₂ reduces the total anisotropy, K_u1+K_u2, but no significant change in the ratio of K_u2/K_u1 was observed. The fabrication of CoPtCr-SiO₂ media with adequate values of K_u1 and K_u2 was successfully demonstrated, although more intensive efforts to enhance grain isolation are required to confirm the advantages conferred by the K_u2 term.