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The structure and magnetic property of as prepared and post-annealed thin films of CoTbNi ternary alloy have been investigated. (Co0.85Tb0.15)1-xNix 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 Co0.85Tb0.15 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. [ABSTRACT FROM AUTHOR]

This work focuses on the study of the influence of the insertion layer (IL) on the magnetic properties of thin films of Co-Tb. Thin films of Ta (5 nm)/Co1−xTbx (20 nm)/Cu (3 nm)/Co1−xTbx (20 nm)/Ta (5 nm) as well as Ta (5 nm)/Co1−xTbx (40 nm)/Ta (5 nm) with x = 0.10 and 0.15 were grown on a silicon substrate using DC magnetron sputtering. The X-ray diffraction patterns indicate the amorphous nature of all prepared films. The measurement of surface roughness of Ta (5 nm)/Co1−xTbx (20 nm) and Co0.85Tb0.15 (20 nm)/Cu (3 nm)/Co0.85Tb0.15 (20 nm) films using 3D optical profilometer indicates a high surface roughness. The measured out-plane and in-plane magnetic hysteresis (M-H) curves indicate that Ta/Co1−xTbx (40 nm)/Ta films (i.e., without any IL) exhibit nearly magnetic isotropic behavior. However, Ta/Co1−xTbx (20 nm)/Cu (3 nm)/Co1−xTbx (20 nm)/Ta films exhibit in-plane magnetic anisotropy. The in-plane anisotropy was found to be significant for the case of x = 0.10 film with larger effective anisotropy constant (Keff). The values of saturation magnetization and squareness (Sq) of films are found to decrease with Cu insertion layer and it is likely due to the worsening of the Co-Tb/Cu interface. The post-annealing of the Co-Tb films with Cu IL helps to improve the value of MS and Keff but it reduces the HC and the squareness of the hysteresis curve. [ABSTRACT FROM AUTHOR]

Recently, search for novel materials for bit patterned media (BPM) has been very intense due to their potential application in ultra-high-density hard disk drive. In a quest of finding new materials for BPM, we have taken up to study ordered array of nanostructured Co-Tb alloy. Thin films of Ta (1 nm)/Co1−xTbx (24 nm)/Ta (4 nm) (x = 0.10, 0.15, 0.18 and 0.33) alloys were deposited on the barrier layer of auto-assembled anodic alumina template using dc magnetron sputtering to form a nanostructured array, the so-called nanobump. Similar array of compounds on a flat Si substrate was also deposited for comparison (reference sample). The measurement of room temperature magnetization (M) versus field (H) curve indicates that the coercivity and the squareness [Mr/Ms] of nanobumps as well as reference samples were found to increase with increase of Tb content. However, the values of HC and Mr/MS for nanobumps were found to be higher than those of reference samples. The measurements of in-plane and out-plane M-H curves reveal that Co1−xTbx (x = 0.15, 0.20 and 0.33) nanobumps exhibit magnetic isotropy behaviour. The measurements of temperature variation of magnetization demonstrate that these films exhibit ferrimagnetism with a compensation temperature much above the room temperature. [ABSTRACT FROM AUTHOR]