The possibility to change magnetic anisotropy of amorphous TbCo films from out-of-plane to in-plane has been investigated. The effects of TbCo film's thickness and composition on the magnetic anisotropy were investigated together with the effects of growing the TbCo films on a SmCo seed layer. This was studied by sputtering TbCo films of composition Tb_xCo_(100-x) x=16,18,20,22 and 24, with thickness ranging between 2-20 nm, with and without the presence of a 20 nmSm_15Co_85 seed layer. All films were grown in a 130 mT magnetic in-plain field to imprint an in-plane anisotropy. The structure and composition of the films were examined with Rutherford backscattering spectrometry, X-ray reflectivity, and Grazing incidence X-ray diffraction. The magnetic properties of the films were studied with magneto-optic Kerr effect measurement, vibrating sample magnetometer, Kerr microscopy and magnetic force microscopy. The magneto-optic Kerr effect measurement showed that it was possible to change TbCo film's preferred magnetization direction from out-of-plane to in-plane by reducing the film thickness. The SmCo layer made it easier for theTbCo films to change preferred magnetization direction from out-of-plane to in-plane.

Thin films of terbium-cobalt alloy have been deposited by magnetron sputtering. They exhibit an out-of-plane magnetic anisotropy that may result in elongated domains. The effect of thicknesses and compositions on the domain structure has been studied systematically. The composition and thickness of the films have been verified by Rutherford backscattering spectrometry and x-ray reflectivity. The domain structure was imaged by magnetic force microscopy and hysteresis loops were measured by MOKE (Magneto-optical Kerr effect). Very long and contrasted domains are obtained on the as-grown film with a thickness of 290 Å containing 8.1\% of terbium. Similar very elongated domains are obtained for other thicknesses and compositions if the films are demagnetized.