Development of a depth-resolved x-ray magnetic circular dichroism: application toFe/Cu(100) ultrathin films

Abstract

A depth-resolved technique is applied in the x-ray magnetic circular dichroism(XMCD) method by controlling the probing depth of the electron yield XMCDspectra. The usefulness of this technique is demonstrated for the study ofmagnetic structures of 4 and 8 ML Fe films grown on Cu(100), whichare known to exhibit peculiar magnetic depth profiles. It was directlyshown that the 4 ML film is uniformly magnetized, while the magneticmoment is localized at the surface in the case of the 8 ML film. The XMCDspectrum for each layer of the 4 ML film was separately extracted. All theextracted spectra were almost identical to each other, confirming theferromagnetic coupling over the whole film. As for the 8 ML film, it wassuggested that the surface two layers are ferromagnetically coupled, while theinner layers are in a spin density wave state with a wavenumber q = 2π/2.4d.