Magnetic Properties of Co-Pt Thin Films Prepared by Sputtering Method and Application to MFM tips

Abstract

CoxPt₁₀₀-x (33 ≤ x ≤ 97) thin films were fabricated by RF sputtering method with various sputtering Ar gas pressure P_Ar and film thickness t and applied to hard magnetic tips for Magnetic Force Microscopy (MFM). The coercivity Hc of Co-Pt films, which were fabricated under high P_Ar, increased in the Co concentration range beyond 60at. % Co. The maximum value of μ₀Hc, 0.27T was obtained for the Co₇₉Pt₂₁ films with P_Ar=10.7Pa and t=40nm. X-ray diffraction analysis revealed that hcp phase exists in the films with high coercivity. The anisotropy field μ₀Ha of the hcp phase was estimated about 1.0T by singular point detection technique. The high coercivity of the films is attributed to domain wall pinning from the minor loop behavior. The MFM tips with Co₇₉Pt₂₁ films on Si cantilevers gave finer contrast in MFM images than commercial CoCr MFM tips for magnetic recording media.