Magnetic surface state becomes nonmagnetic by oxygen adsorption

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Abstract
The influence of oxygen adsorption on a partly occupied spin-split surface state at Ni(111) has been studied by spin-resolved inverse photoemission. With increasing oxygen exposure the surface state shifts to higher energy, thereby becoming totally unoccupied and no longer contributing to the surface magnetic moment. Moreover, its exchange splitting of about 100 meV on the clean surface is reduced to less than 25 meV for the ordered p(2×2) oxygen overlayer, whereas the splitting of an sp bulk band transition remains unaffected. The data demonstrate on a microscopic level the oxygen-induced reduction of the magnetic moment at the surface of Ni(111).