Berlin 2005 – scientific programme
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O: Oberflächenphysik
O 52: Elektronische Struktur IV
O 52.6: Talk
Wednesday, March 9, 2005, 12:00–12:15, TU EB301
Electrons in the competing potentials of a Moiré-type — •Christian R. Ast1, Daniela Pacilé1, Marco Papagno1, Gero Wittich2, Klaus Kern1,2, and Marco Grioni1 — 1Ecole Polytechnique Fédérale de Lausanne, Lausanne — 2Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany
The effects of weak changes in the periodic potential on the electronic structure can be nicely studied in overlayer structures showing a Moiré-type superlattice. Angular resolved photoemission spectroscopy is used to study the valence bands of Pb on Ag(111), which produces a hexagonal Moiré superlattice at monolayer coverage having a lattice constant incommensurate with the surface. The measured electronic structure of the Pb monolayer is hardly influenced by the substrate due to the mismatch in lattice constants. However, within the monolayer the electrons feel the presence of two competing periodicities: The hexagonal primitive cell in the plane of the monolayer as well as the characteristic modulation of the Moiré structure normal to the monolayer plane with a much larger unit cell. A scenario will be proposed in which the superimposed modulation is not strong enough to change the Brillouin zone but does influence the overlap of orbitals normal to the monolayer plane.