Magnetic and magneto-optical properties of cobalt-platinum alloys with perpendicular magnetic anisotropy

Co1-xPtx alloys with Pt contents in the range 0.45≤x≤0.9 show sizable perpendicular magnetic anisotropy, 100% perpendicular remanence and coercivities in the range 160 kA/m. Thin films of this material are grown by electron beam evaporation onto fused silica or Si, at substrate temperatures between 150 and 350°C. Spectroscopic investigations of the polar Kerr rotation show a significant enhancement of the Pt related UV peak. A comparison of the static signal levels R×(θk2+εk2)1/2 of Co/Pt multilayers and alloys shows an overall 50% enhancement in the case of alloys. Curie temperatures around 200°C are observed for Co∼22Pt ∼78 compositions. These properties, together with the potentially high chemical stability and ease of manufacturing make Co1-xPt x alloys very attractive materials for short wavelength magneto-optic recording.