Fe-Co-B/[Ni-Fe/Si] soft magnetic underlayer with high anisotropy field along cross-track direction on disk substrate

The origin of high anisotropy field Hk and low coercivity Hc of Fe-Co-B/Ni-Fe double-layered films with high saturation magnetization 4πMs was investigated. In-plane and out-of-plane X-ray diffractometry studies clarified that the lattice spacing of crystallites along the easy axis direction was expanded compared to that along the hard axis direction. It was confirmed that such an anisotropic residual stress caused the magnetic anisotropy energy of the double-layered film through magnetoelastic effect. Investigation of Ar gas pressure dependence of Hk suggested that the origin of the residual stress was due to the oblique incidence of sputtered particles. In order to align the orientation of magnetic anisotropy field along the cross-track direction, a Fe-Co-B/Ni-Fe double-layered soft magnetic underlayer was deposited on a rotating disk. The Fe-Co-B/Ni-Fe double-layered films on the rotating disk exhibited Hk values above 200 Oe along the radial direction of the disk in the whole area of the disk.