SPIN-RESOLVED PHOTOEMISSION-STUDY OF OXYGEN ON THIN COBALT FILMS

Investigations concerning the magnetic interactions and dispersion eff ects of oxygen adsorbed on thin cobalt films have been carried out by angle and spin resolving photoelectron spectroscopy. Cobalt evaporated on W(110), showing the surface of a h.c.p. (0001) crystal, served as ferromagnetic substrate. Photoelectron spin analysis allows the distin ction between chemisorbed oxygen and cobalt oxide in its different oxi dation states (antiferromagnetic CoO and Co3O4) at different substrate temperatures. The exchange splittings of the adsorbate derived bands of chemisorbed oxygen are investigated as a function of excitation ene rgy, coverage, temperature, and emission angle. The non-vanishing spli ttings give evidence for an induced magnetic moment within the adsorba te layer.