Soft X-ray Fluorescence Study of Buried Silicides in Antiferromagnetically Coupled Fe/Si Multilayer

Soft x-ray fluorescence spectroscopy has been employed to obtain information about the Si-derived valence band states of Fe/Si multilayers. The valence band spectra are quite different for films with and without antiferromagnetic interlayer exchange coupling, demonstrating that these multilayers have different silicide phases in their spacer layers. Comparison with previously published fluorescence data on bulk iron silicides shows that the Fe concentration in the silicide spacer layers is substantial. Near-edge x-ray absorption data on antiferromagnetically coupled multilayers in combination with the fluorescence data demonstrate unambiguously that the silicide spacer layer in these films is metallic. These results on the electronic structure of buried layers in a multilayer film exemplify the wide range of experiments made possible by new high-brightness synchrotron sources.