Contesting results for magnetic moments in nickel thin films

We report on Korringa-Kohn-Rostoker Green's function calculations for the ground-state moments of ultrathin Ni films on Cu(001) and on four monolayers (ML) Co/Cu(001). The calculations for Ni/Cu(001) show a slight enhancement of the Ni magnetic moment at the surface but a large reduction of the Ni magnetic moment at the Cu interface. The number of d holes at the surface and interface shows a small reduction. However, for Co/Cu(001) the calculation gave only a slightly decreased interface magnetic moment. For Ni on a ferromagnetic substrate, such as 4 ML Co/Cu(001), no reduction of the magnetic moment occurs, so that Ni at the interface retains its bulk value. These results are in contradiction with recent experimental results obtained using x-ray magnetic circular dichroism on ferromagnetic Ni films grown epitaxially on ultrathin films of Co. For decreasing film thickness, the number of holes and the magnetic moment show a gradual decrease.