The magnetic and magneto-optic properties of amorphous Tb.17 (Fe1-yCoy).83 and Dy.20 (Fe1-yCoy).80 films have been investigated.
As in the case of Gd.26 (Fe1-yCoy).74 films, an increase of the Kerr rotation θK. with increasing Co content y has been found for Tb-(Fe1-yCoy) and Dy-(Fe1-yCoy) films in the range of 0<y<0.3, measured at room temperature with a wavelength of 633 nm. The enhancement of θK is considered to be mainly due to the rise of the Curie temperature TC caused by the Co substitution. Another reason might be the increase of the Fe-Co moment at 0 K.
The dependence of θK on wavelength λ in the range of 400 nm<λ<800 nm has also been measured for these films. The results show that the slope of the normalized spectrum ((1/θK)·(dθK/dλ)) decreases with increasing y, approaching the spectrum for pure Co metal. In addition, a dependence of the spectra on the type of rare earth atoms could be seen for short wavelength (λ∼400 nm).
The product of magnetization and coercivity of Tb-(Fe1-yDoy) films increases with increasing y at room temperature in the range of 0≤y≤0.3. This may also be attributed to the rise of TC.
