Direct observation of oscillatory behavior in the surface magnetization of Fe thin films grown on a Ni/Cu(100) film

The surface and interface magnetic structures of Fe thin films (4-11 ML) grown on a 6 ML Ni/Cu(100) film have been directly investigated with the depth-resolved x-ray magnetic circular dichroism technique. An oscillatory behavior in the Fe surface magnetization as a function of Fe thickness is found. The spectra were analyzed with a simple magnetic model, in which only surface two layers and interface (bottom) single layer are magnetically active. The analysis clearly shows existence of an oscillatory or rotational interlayer magnetic coupling between the surface and interface of the Fe film via the inner layers with the interface magnetization essentially unchanged. Temperature dependent experiments showed that the surface magnetization vanishes with increasing temperature, while the interface one stays unchanged.