Dry-etching damage to magnetic anisotropy of Co-Pt dot arrays characterized using anomalous Hall effect

Using high-resolution e-beam lithography and ion beam etching, dot arrays were formed from Co-Pt alloy films with perpendicular magnetization. Dry-etching damage to uniaxial magnetic anisotropy K u of the fabricated dot arrays was examined. Hcp-Co 75 Pt 25 films and L 1 1 -type Co 50 Pt 50 -ordered alloy films with film thickness δ of 3, 5, and 10 nm were used for this study. Dot diameter D was varied from 10 nm to 400 nm. The effective magnetic anisotropy of the dots, K u eff , was measured using the generalized Sucksmith-Thompson method with anomalous Hall effect (AHE) and an averaged AHE signal over 100-71,000 dots. By compensating the dot shape anisotropy, K u was calculated from K u eff . The K u for a dot array of D = 400 nm was almost equal to that for an original continuous film, but K u decreased gradually for D