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−xPtx alloys very attractive materials for short wavelength magneto-optic recording.

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CoPt alloy films with large perpendicular magnetic anisotropy, perpendicular coercivity, and saturated perpendicular remanence are reported. These films were fabricated by e-beam evaporation at substrate temperatures near 200 °C and above. Well-(111)-textured Pt underlayers are shown to dramatically increase the perpendicular magnetic anisotropy of CoPt alloy films. The large perpendicular magnetic anisotropy is shown to be strongly related to good CoPt(111) texture, and not to the ordered tetragonal Co50Pt50 phase.

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Electron beam patterned permalloy circular dots of 700 nm diameter with small separations were studied by magnetic force microscopy (MFM) in the presence of an in situ magnetic field. Images in the demagnetized state show that the dot is in a vortex state with a vortex core (singularity) in the center. Local hysteresis loops, measured by cantilever frequency shift in an external field, indicate that the magnetization reversal of individual disks is a vortex nucleation and annihilation process. By carefully doing MFM, nucleation and annihilation fields without MFM tip stray field distortions are obtained. Configurational anisotropy originated from magnetostatic coupling is found through hysteresis loops. © 2002 American Institute of Physics

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