Magneto-optical recording media of GD based amorphous alloy systems with high kerr rotation

To obtain practical magnetooptical materials having large Kerr rotation Θk, high perpendicular coercivity Hc and relatively low Curie temperature Tc(
\sim200\deg
C), rare-earth elements having a one-ion anisotropy were added to Gd-Fe-Co amorphous alloy system, which has a large intrinsic Kerr rotation but an in-plain anisotropy. As a result, replacing Gd by Tb,Dy,Ho, a large perpendicular anisotropy Ku is induced associating with the increase of Hc. With the optimization of their compositions, Gd-R-Fe-Co (R=Tb,Dy,Ho) amorphous films with Θk= 0.42-0.45° (at the wavelength of 822nm), Tc
\sim200\deg
C, and Hc=160-400 kA/m(2-5 kOe) were obtained.