Magnetic and Magneto-Optical Properties of Amorphous TbFeCoBi Thin Films

Bi was added to TbFeCo and its effects on the TM sublattice magnetization (M_TM) were studied. The Kerr rotation angle (θ_K) was low at all Co concentrations. The addition of Bi increases μ_TM, but has comparatively little effect on M_TM. Bi increases θ_K in Gd-TM films, but decreases θ_K in Tb-TM films. This can be attributed to RE-Bi interactions. When both Tb and Gd were used (TbGdFeCoBi films), increasing the amount of Gd made θ_K rise at three times the rate of increase in TbGdFeCo films.