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O: Fachverband Oberflächenphysik
O 89: Metal Substrates: Epitaxy and Growth
O 89.11: Talk
Friday, February 29, 2008, 12:00–12:15, MA 041
DFT study of epitaxial graphene on Ru(0001) — •bin wang1, marie-laure bocquet1, stefano marchini2, sebastian günther2, and joost wintterlin2 — 1Laboratoire de Chimie, Ecole Normale Supérieure de Lyon, Lyon, France — 2Department Chemie, Ludwig-Maximilians-Universität München, München, Germany
Graphene is a flat monolayer of carbon atoms with a honeycomb lattice, which has been a rising star in materials science for its unique electronic structure. It can also grow on surfaces if the lattice constants of the surface and of graphene match. In case of lattice mismatch, as in the case of metal surfaces like Ru(0001) [1] or Ir(111) [2], epitaxial growth leads to a moiré structure. We have investigated epitaxial graphene on a Ru(0001) substrate by means of large-scale density functional theory (DFT) calculations. We show that, contrary to other substrates, the graphene electronic structure displays massive local changes, alternatingly varying between a zero gap and a band gap of 2 eV. This result is caused by alternating weak and strong contact areas of the graphene on the Ru surface, correlated with a large geometric buckling of 1.5 Å over the 30 Å periodic moiré superstructure. The mismatching lattice between graphene and the substrate thus leads to a changing symmetry and electronic structure that both vary regularly on the nanometer scale. The results are in good agreement with recent STM experiments [1].
[1] Marchini S., Günther S. & Wintterlin J., Phys. Rev. B. 76, 075429 (2007) [2] N'Diaye A.T., Bleikamp S., Feibelman P. J. & Michely T., Phys. Rev. Lett. 97, 216501 (2006)