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O: Oberflächenphysik
O 6: Struktur und Dynamik reiner Oberflächen
O 6.7: Vortrag
Montag, 8. März 2004, 12:45–13:00, H45
Surface phase diagram of the CoAl(100) surface — •Ole Wieckhorst1, Stefan Müller1, Lutz Hammer1, Klaus Heinz1, Ralph Drautz2 und Manfred Fähnle2 — 1Universität Erlangen-Nürnberg, Lehrstuhl für Festkörperphysik, Staudtstr. 7, 91058 Erlangen — 2Max-Planck-Institut für Metallforschung, Heisenbergstr. 3, 70569 Stuttgart
For ideal bulk stoichiometry, the (100)-surface of B2-ordered Co-Al shows a termination by the Al-sublattice. However, a tiny surplus of Co-atoms in the bulk leads to the segregation of these so called anti-site atoms to the (100)-surface [1]. We use a combination of density functional theory with cluster expansions and Monte-Carlo simulations to study not only the local atomic structure of these antisites, but also temperature dependent short-range order phenomena at the surface. This leads to the construction of a phase diagram of the near surface layers. The stable structures predicted are in excellent agreement with those received from LEED structure determinations. (supported by DFG)
[1] V. Blum et al., Phys. Rev. Lett. 89, 266102 (2002)