Surface magnetism of iron films following the adsorption of oxygen: a comparison between Fe/Ag(100) and Fe/MgO(100)

The correlation between crystallographic order and surface magnetism has be en investigated by studying the chemisorption of oxygen on iron films grown on Ag(100) and MgO(100). The exchange splitting of O 2p states depends str ongly on surface order as it decreases from Delta E-o (2p) similar or equal to 0.5 eV for the O(1 x 1) phase to Delta E-o (2p) similar or equal to 0.2 eV for the O/Fe/MgO disordered phase. Even smaller values of Delta E-o (2p ) are obtained for the highly disordered O/Fe/Ag system, demonstrating that the coupling of oxygen states with the magnetic film underneath is strongl y affected by crystallographic order. (C) 1999 Elsevier Science B.V. All ri ghts reserved.