Surface magnetism of oxygen adsorbed on a Fe/Ag(100) film

The influence on surface magnetism of oxygen adsorption at T=120 K on an iron film grown on Ag(100) has been analysed by spin polarized metastable deexcitation spectroscopy. The low temperature has been chosen in order to reduce the segregation of silver at surface. SPMDS data have been interpreted by a model that provides the effective charge and magnetization densities. At 120 K, oxygen chemisorbs atomically, the O-2p slates are spin polarized and show a ferromagnetic coupling with the substrate. The energy shift between the majority and the minority density of states is a function of exposure as it decreases from 0.24 eV at 0.25 L to zero for exposures higher than 1.6 L. At exposures of about 1 L, oxygen starts a process that leads, at 3-4 L, to the formation of a layer that is magnetically dead as observed by He*.