Adsorbate-induced demagnetization and restructuring of ultrathin magnetic films: CO chemisorbed on gamma-Fe/Cu(100) - art. no. 094418

First-principles local-spin-density (LSD) investigations of the structural. magnetic, and electronic properties of clean and CO-adsorbed ultrathin gam ma -iron films epitaxially grown on Cu(100) surfaces demonstrate that both the geometrical and the magnetic structures of the films are profoundly mod ified by the adsorption of CO. The enhanced magnetic moments of the top-lav er atoms are strongly quenched by the presence of the adsorbate. Due to the pronounced magnetovolume effect, this leads also to a correlated change in the interlayer relaxations. Strikingly, the adsorbate-induced demagnetizat ion is primarily limited to those surface atoms directly bonded to the adso rbate. This leads to the formation of an in-plane magnetic pattern in a par tially adsorbate-covered film. The comparison of the calculated vibrational eigenfrequencies of the CO adsorbate with experiment confirms the picture based on the LSD calculations.