Interface properties and electronic structure of ultrathin manganese oxide films on Ag(0 0 1)

Ultrathin manganese monoxide films on silver single crystal substrates are studied as a function of the thickness using X-ray absorption spectroscopy (XAS) and X-ray photoemission spectroscopy (XPS). It was found that electronic and geometric properties in ultrathin films differ from the bulk. A tetragonal distortion of the oxide films is revealed by polarisation-dependent X-ray absorption measurements: the extent decreases with increasing film thickness. A structural relaxation of epitaxial oxide layers induced by heating also leads to a decrease of the tetragonal interface strain. The electronic structure of ultrathin manganese oxide films in the valence band region is very similar to that in the bulk oxide.