Thickness dependence of the microstructure and magnetic anisotropy of sputtered Fe50Ni50 films.

Fe₅₀Ni₅₀ thin films were prepared by dc magnetron sputtering with a field of ∼40 mT applied parallel to the plane of the film. The microstructure and magnetic anisotropy of the films have been studied as a function of film thickness, which was varied from 13–1100 nm. Vibrating sample magnetometer and magnetic force microscope measurements show that only the very thinnest films (13 nm) showed an out-of-plane magnetic component. The in-plane anisotropy strongly depended on the thickness of the film: films with thickness of <=20 nm were magnetically isotropic with perfectly square B-H loops; when the thickness increased to 30 nm, the film began to show in-plane anisotropy with the magnetic easy axis parallel to the direction of the magnetic field applied during sputtering. The easy axis direction was confirmed by both magneto-optic Kerr effect and B-H loop tracer measurements. [ABSTRACT FROM AUTHOR]