Magnetic circular dichroism of Fe/Pd(100) ultrathin films

Abstract

In this work, surface magnetic anisotropy and magnetism of ultra-thin bct Fe films epitaxially grown on a fcc Pd(100) substrate (notated Fe/Pd(100)) are studied in the monolayer range. To investigate the relation between the film structure and the magnetic anisotropy we studied the growth by Auger electron spectroscopy and low-energy electron diffraction. The results are compared with recent studies. At room temperature the film grows pseudomorphically with island formation starting before the completion of the first iron layer. The bct structure of the film, in particular the extended interlayer relaxation in the film has been analyzed. These data were compared with the case of low-temperature grown films which display great differences both in the morphology of the thin films and in their crystallographic structure. Magnetic circular X-ray dichroism measurements have been performed on the FeL 2.3 absorption edges. In the case of Fe/Pd(100) ultra-thin films, the high Curie temperature still favours ferromagnetism at room temperature for two equivalent monolayers Fe/Pd(100). The results show a strong in-plane anisotropy and a greatly enhanced magnetic orbital moment in the ultra-thin Fe films grown at room temperature. This surprising anisotropy at room temperature can be related to the growth and the structure of the film.