Magneto-optical response of ferrimagnetic Tb-Fe thin films in the visible and ultraviolet range

We present wavelength-dependent measurements of Kerr rotation and ellipticity for ferrimagnetic Tb₃₀Fe₇₀ thin films in the optical range of 225 nm–726 nm (1.7 eV to 5.5 eV). The thicknesses of the magnetic layers vary from 19 nm to 83 nm. Strong optical interference effects in the magneto-optical spectra are observed for films grown on commonly used SiO₂/Si substrates, which may easily be misinterpreted as spectral signatures of Tb. This strong optical interference feature can be fully suppressed by depositing magnetic Tb-Fe films on glass substrates. (paper)