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

Abstract

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.

Interface magnetic anisotropy in cobalt clusters embedded in a platinum matrix

“…3). The low Curie temperature of CoPt disordered alloys has already been pointed out by Weller et al 21 or Devolder 22 . We further annealed this sample during 10 minutes at T=450 • C under a vacuum of 10 −7 Torr.…”

Ab InitioTheoretical Description of the Interrelation between Magnetocrystalline Anisotropy and Atomic Short-Range Order

“…We also note that thick fcc-Co c Pt 1−c [8][9][10] and fcc-Co c Pd 1−c [8] films exhibit PMA of a size comparable with that of multilayers. Such a large PMA is quite unexpected for systems which should have effectively bulk cubic structure.…”

“…These are also summarised in Table II [8][9][10] which is attributed to the existence of internal interfaces [12], analogous to Co and Pt layers along the [111] direction. Our result is clearly consistent with these observations.…”

Magnetic properties of nanometer-size CoPt particles

“…CoPt alloy thin films have received significant attention as possible magneto-optic recording media owing mainly to the existence of ordered intermetallic phases with exceptional magnetic properties. 4,5 CoPt compounds are known for their hard magnetic properties. In the bulk form, it shows a high magnetocrystalline anisotropy ͑4ϫ10 7 ergs/cm 3 ͒ and a relatively large saturation magnetization M s ϭ800 emu/cm 3 .…”