ELECTRONIC-STRUCTURE OF SAMARIUM ATOMS ADSORBED ON THE GAAS(110) SURFACE

The electronic structure of samarium atoms adsorbed on a GaAs(110) surface is calculated in the tight-binding approximation. It is shown that in the ground state, this adatom is divalent at low coverage when it is adsorbed on Ga surface atoms. The adsorption unrelaxes the surface atoms close to the adatom. Charge transfer from the adatom leads to a strong Coulomb potential and to a bonding state localized close to the conduction band minimum. Comparison is made with surface atom core-level shifts and valence and conduction band states measured by photoemission spectroscopy.