Dependence of the magnetic properties of nanocrystalline nickel films on grain size and surface morphology

Nickel films prepared by direct-current, pulse-current, and pulse reverse-current electrodeposition are studied. Scanning electron microscopy and atomic force microscopy show that the films consist of fine grains. The electrodeposition conditions are varied to prepare films with different grain sizes and surface roughness. All the films are magnetically isotropic. In films with a grain size comparable to the width of Bloch domain walls, the magnetization reversal occurs owing to the incoherent rotation of magnetization. In films with a grain size of more than 350 nm, the magnetization reversal occurs not only through the incoherent rotation of magnetization, but also owing to the nucleation and displacement of the domain walls.