3s photoemission spectra of Fe/Cu(100) films.

A simple cluster model calculation scheme which successfully describes the line shape and intensity ratio of recent spin resolved Fe 3s spectra of metallic Fe has been developed. From fitting the 3s spectra of bcc-bulk Fe, we found that the configuration interaction effect is important to the understanding of the 3s spectra. This model was applied to the Fe 3s spectra obtained from the ultrathin @0.7, 1.7, and 2 monolayer ~ML!# Fe overlayers on Cu~100!, and the 3s spectra of thin films were described well within our cluster model framework. Indeed the difference between the Fe 3s spectra of ultrathin films and bulk-bcc Fe was found to be consistent with the fact that the local magnetic moment of ultrathin films is smaller than that of the bcc bulk in our model. However, we did not find significant changes of the experimental 3s spectra between 0.7-, 1.7-, and 2-ML-thin films, which means that local magnetic moments of thin films do not change much below 2 ML.