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 been 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 strongly on surface order as it decreases from Δ E O 2p ≃0.5 eV for the O(1×1) phase to Δ E O 2p ≃0.2 eV for the O/Fe/MgO disordered phase. Even smaller values of Δ 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 strongly affected by crystallographic order.