Magnetic and magneto-optic properties of amorphous Gd-Fe-Co and Gd-Fe-Co-Bi films

Amorphous Gdx(Fe1-yCoy)1-x(0.24<x<0.26, 0<y<1) films, for which an increase of the Kerr rotation with increasing Co content y in the range of 0<y <0.3 at 300K has been reported, have been prepared by rf-sputtering. The average transition metal moment μTMat 4.2K has been measured for these films and it can be seen that μTMremains almost constant in the range of 0<y<0.3, which might be caused by an increase of the Fe moment. The enhancement of the Kerr rotation for the present Gd-Fe-Co films can be explained by this behavior of μTMand the rise of the Curie temperature. Amorphous (Gd.26(Fe.70Co.30).74)1-zBiz(0<z<0.12) films have been prepared by co-evaporation, and a further enhancement of the Kerr rotation has been observed in the composition range of 0<z<0.09 and a wavelength range of λ > 500nm at room temperature.