Dresden 2003 – wissenschaftliches Programm

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O: Oberflächenphysik

O 21: Adsorption an Oberfl
ächen II

O 21.9: Vortrag

Dienstag, 25. März 2003, 17:00–17:15, HSZ/03

Long-range interactions between magnetic 3d adatoms on Cu(111) — •L. Niebegrall¹, V.S. Stepanyuk², A.N. Baranov¹, W. Hergert¹, and P. Bruno² — ¹Fachbereich Physik, Martin-Luther-Universität, Halle-Wittenberg — ²Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle, Germany

Surface-state electrons on the (111) surfaces of noble metals form a two-dimensional nearly free electron gas. The quantum interference between the electron wave traveling towards the scattering defect and the backscattered one leads to standing waves in the electronic local density of states (LDOS) around the defect. Oscillations of the electron density around adsorbates on a metal surface lead to a long-range oscillatory Friedel-type adsorbate-adsorbate interaction [1]. Such interactions can significantly influence surface diffusion and the growth morphology. In the case of magnetic adatoms indirect exchange coupling between spins of adatoms is involved in the interactions. We apply density functional theory and Korringa-Kohn-Rostoker Green’s function method [1] for calculations of long-range interactions between magnetic 3d adatoms on Cu(111). Ferromagnetic and antiferromagnetic pairs of the 3d adatoms at different separations are considered and the exchange energies are calculated. Comparison of our results with recent experiments shows very good agreement [2].

[1] V.S. Stepanyuk, A.N. Baranov, W. Hergert, P. Bruno, N. Knorr, M.A. Schneider, and K. Kern, Phys. Rev. Lett. subm.

[2] N. Knorr, H. Brune, M. Epple, A. Hirstein, M.A. Schneider, and K. Kern, Phys. Rev. B 65, 115420 (2002).