A comparative study of local magnetic properties of vanadium and chromium adsorbed on graphite

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Abstract
Recently vanadium 3s core-level X-ray photoemission of freshly evaporated V clusters on graphite exhibited a satellite structure, which has been assigned to magnetic moments of V adatoms. More generally the condition for the appearance of local magnetism in the case of 3d metal atoms adsorbed on a graphite surface is still an open question. In this paper we extend a previous extra-orbital tight-binding electronic-structure model to the cases of V and Cr isolated adatoms upon graphite. The equilibrium position of an adsorbed atom is found with a Born-Mayer repulsive term and the energy levels are chosen so as to satisfy Friedel's screening rule. The Hartree-Fock approximation has been used for the determination of the onset of local magnetism on a V or a Cr adatom. We discuss our results for two closely related cases of early 3d transition metals on graphite, i.e. V and Cr.