Spin-reorientation transition of Ni/Cu(100) and CO/Ni/Cu(100): Separation of the surface and bulk components of the x-ray magnetic circular dichroism spectrum

The spin-reorientation transition of Ni/Cu(100) and CO/Ni/Cu(100) films was investigated with the depth-resolved x-ray magnetic circular dichroism (XMCD) technique. The XMCD spectra from the surface and inner layers were separately extracted. As for the bare Ni films, the in-plane orbital magnetic moment in the surface layer is significantly enhanced. In contrast, the inner layers exhibit larger perpendicular orbital magnetic moment than the in-plane one. Upon CO adsorption, the surface magnetization is drastically reduced, while the inner layers are unaffected. These results directly explain the spin-reorientation transition in Ni/Cu(100) and CO/Ni/Cu(100)