Surface etching effect of Co80Pt20-SiO2 granular media

We have fabricated Co-Pt alloy-SiO₂/Cr granular media and etched by RF biasing the magnetic layer surface to reduce the effect of isolation and finer Co-Pt grains. The magnetization decreased slightly with film thickness reduction. The in-plane coercivity H_c was maintained down to a magnetic layer thickness of 11 nm. Meanwhile, the perpendicular H_c decreased with reduced film thickness. This indicates that the magnetization easy axes orientations of the grains in the etched layer were 3D-random and that epitaxial growth occurs on the Cr under layer. Signal at high linear densities was increased with film etching presumably due to the good easy axes orientation of the remaining layer. The signal to media noise ratio was improved by 1 dB but the thermal stability of magnetization was slightly lessened