Magneto-optical properties of (Pr,Nd)-(Tb,Dy)-FeCo amorphous films

A systematic study of magnetooptical properties for four different varieties of the (Pr,Nd)-(Tb,Dy)-FeCo system, focusing on temperature and wavelength dependences of Kerr rotation theta /sub k/ for alloy films and multilayered films, was made. The same relation between Curie temperature T/sub c/ and theta /sub k/ at a 830-nm wavelength was obtained for (Pr,Nd)-(Tb,Dy)-FeCo and (Tb,Dy,GdTb)-FeCo alloy films where the Co to FeCo ratio was less than 20 at.%. It was found that in the range of 500 nm to 900 nm the absolute magnitude of theta /sub k/ for all quaternary systems was always less than that for Dy-FeCo. These results suggest that amorphous rare-earth-FeCo alloy films containing Nd or Pr are not superior to (Tb,Dy)-FeCo films in regard to recording sensitivity and recording density in magnetooptical disks. On the other hand, theta /sub k/ enhancement was observed for Nd-Dy-FeCo multilayered films. This theta /sub k/ enhancement is not caused by the addition of Nd, but is due to the effect of film microstructure on theta /sub k/. >