Magnetic and Magneto-Optic Properties of Amorphous Dy-Fe-Co and Tb-Fe-Co Films

Abstract

The magnetic and magneto-optic properties of amorphous Tb.₁₇ (Fe_1-yCo_y).₈₃ and Dy.₂₀ (Fe_1-yCo_y).₈₀ films have been investigated.
As in the case of Gd.₂₆ (Fe_1-yCo_y).₇₄ films, an increase of the Kerr rotation θ_K. with increasing Co content y has been found for Tb-(Fe_1-yCo_y) and Dy-(Fe_1-yCo_y) films in the range of 0<y<0.3, measured at room temperature with a wavelength of 633 nm. The enhancement of θ_K is considered to be mainly due to the rise of the Curie temperature T_C caused by the Co substitution. Another reason might be the increase of the Fe-Co moment at 0 K.
The dependence of θ_K 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/θ_K)·(dθ_K/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-(Fe_1-yDo_y) 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 T_C.