Effect of Co Replacement with Fe on Uniaxial Magnetocrystalline Anisotropy in Disordered hcp CoPtRh Alloy Films

The effect of replacing Co with Fe in disordered CoPtRh alloy films was investigated with the aim to increase the spin magnetic moment. The addition of Fe into a pure Co film produced a Co₉₈Fe₂ film with maximum uniaxial magnetocrystalline anisotropy (K_u), because the magnetic moment is increased with the same degree of stacking faults (SFs) induced into the hcp grains as that for a pure Co film. (Co_0.98Fe_0.02)PtRh films were compared with CoPtRh films with the same Pt and Rh contents, which revealed that: 1) the degree of SFs were increased; 2) the magnetic moment was increased; and 3) K_u was decreased for all compositions in the (Co_0.98Fe_0.02)PtRh films. In particular, the (Co_0.98Fe_0.02)PtRh and CoPtRh films with a larger Rh content than Pt have a greater range for increase of the K_u magnitude by enhancement of the magnetic moment with the retention of or further decrease in the degree of SFs.