Comparison of chlorine and oxygen adsorption on the ferromagnetic Fe(0 0 1) surface: Density-functional theory study

We compare chemisorption of Cl and O on the ferromagnetic Fe(0 0 1) surface by using density-functional theory calculation. p( 2 × 2 ) and p( 1 × 1 ) adsorbate overlayers are considered. The chlorine adsorption resembles in most respects the previously thoroughly studied oxygen deposition, although the Cl atom is well separated from the subsurface-layer Fe atom and, at low coverage, its induced magnetic moment is very small: 0.06 μ B . For the p( 2 × 2 ) structure, the spin-resolved local density of electronic states is dominated by exchange-splitted peaks of O(2p) or Cl(3p) character. The calculations are employed to discuss the data obtained recently by the new spin-polarized ion-scattering experimental technique [T.T. Suzuki et al., Surf. Sci. 602 (2008) 1688] for oxygen and chlorine adsorption on Fe(0 0 1). It remains to show whether the experimentally found significant difference between the signal from oxygen and chlorine, respectively, can be explained by the comparatively little differing electronic properties of the two adsorbates, or whether the signal from O does not rather reflect partly properties of the surface iron atoms. For chlorine, the latter mechanism might be suppressed due to its large atomic radius.