Influence of Cu Insertion Layer on Magnetic Properties of Co-Tb/Cu/Co-Tb Thin Films

Abstract

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)/Co_1−xTb_x (20 nm)/Cu (3 nm)/Co_1−xTb_x (20 nm)/Ta (5 nm) as well as Ta (5 nm)/Co_1−xTb_x (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)/Co_1−xTb_x (20 nm) and Co_0.85Tb_0.15 (20 nm)/Cu (3 nm)/Co_0.85Tb_0.15 (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/Co_1−xTb_x (40 nm)/Ta films (i.e., without any IL) exhibit nearly magnetic isotropic behavior. However, Ta/Co_1−xTb_x (20 nm)/Cu (3 nm)/Co_1−xTb_x (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 (K_eff). 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 M_S and K_eff but it reduces the H_C and the squareness of the hysteresis curve.