Magnetic Property of CoTbNi Ternary Alloy Thin Films

The structure and magnetic property of as prepared and post-annealed thin films of CoTbNi ternary alloy have been investigated. (Co_0.85Tb_0.15)_1-xNi_x alloy thin films with x = (0.54, 0.63, 0.72, 0.81) were grown on Si-substrate by co-sputtering of Ni element and Co_0.85Tb_0.15 alloy using dc magnetron sputtering. These films have been crystallized in amorphous form, as confirmed by X-ray diffraction (XRD) measurement. The magnetization versus field measurements shows that these films exhibit room temperature ferromagnetism. The magnetic properties of these alloy films have a strong dependency on the Ni concentrations. It is observed that the saturation magnetization and coercivity of these alloy thin films decreases with increase of Ni content of the films. One of the striking features was the observation of perpendicular magnetic anisotropy (PMA) for x = 0.63 and 0.72 thin films. However, the observed PMA disappears upon post-annealing of the films. The M-T measurement shows that the ferromagnetic transition temperatures of these materials are much higher than the room temperature.