Electrochemical deposition of novel nanostructured magnetic thin films for advanced applications

Nanostructured NiW films (140 nm) containing from zero to 18-wt.% W have been electrolytically processed and analyzed. XRD, SEM and TEM investigations revealed that films consist of Ni columnar nanoparticles of fcc-type whose [111] axis is oriented perpendicular to the film plane and have 140 nm tall and d=6–27 nm in diameter. Depending on film composition, two types of nanostructures were observed; (a) single-phase nanostructure (<7-wt.% W, d=14–27 nm), and (b) two-phase nanostrueture (7–18-wt.%, d=6–14 nm). The particle size dependence of saturation magnetization, in-plane and, respectively, perpendicular coercivity is typical for a single-domain Ni particle system, and can be controlled by W content. Typical film containing 13-wt.% W behaves that a system of perpendicular Ni columns 12–13 nm in diameter embedded in an amorphous NiW matrix with perpendicular magnetic anisotropy. Such film has the following magnetic parameters: Ms=420, Hc//=49, H⊥=118, Hk=455 kA m−1, quite high squareness ratio S=0.6 and very high coercivity squareness S*=0.83. It is conclude that such a film may be used as a perpendicular magnetic recording media with ultrahigh density.