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 nanostructure (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: M-s = 420, H-cll = 49, H-perpendicular to = 118, H-k = 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. (C) 2002 Elsevier Science B.V. All rights reserved.