ELECTRONIC-STRUCTURE OF ULTRATHIN FE FILMS ON TIO2(110) STUDIED WITH SOFT-X-RAY PHOTOELECTRON-SPECTROSCOPY AND RESONANT PHOTOEMISSION

We report on soft-x-ray photoelectron spectroscopy (SXPS) of a TiO2(11 0) surface during deposition of Fe in the monolayer regime. At low fra ctional monolayer coverages, the adsorbed Fe atoms are oxidized and Ti cations at the interface become reduced due to Fe adsorption. SXPS fr om shallow core levels and valence bands show that Fe starts to exhibi t metallic character at a coverage of approximately 0.7 equivalent mon olayers. Two well separated defect states appear in the band gap of Ti O2 at iron coverages well below one monolayer. We use resonant photoem ission to obtain information on the partial density of states, and we assign these defect states as being Fe-derived and Ti-derived states; located at the Fe and Ti sites, respectively. We suggest that a positi on change of oxygen is involved in the bonding of Fe on the TiO2(110) surface.