Dresden 2014 – scientific programme
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O: Fachverband Oberflächenphysik
O 36: Posters: Bio/organic Molecules on Surfaces, Graphene, Solid/liquid interfaces, Metal Substrates, Electronic Structure Theory
O 36.55: Poster
Tuesday, April 1, 2014, 18:30–22:00, P1
many-body interactions in the sigma band of graphene — •federico mazzola1, justin wells1, rositza yakimova2, soren ulstrup3, jill miwa3, richard balog3, marco bianchi3, mats leandersson4, johan adell4, philip hofmann3, and thiagarajan balasubramanian4 — 1Department of Physics, Norwegian University of Science and Technology (NTNU), N-7491 Trondheim, Norway — 2Department of Physics, Chemistry, and Biology, Linkoping University, S-581 83 Linkoping, Sweden — 3Department of Physics and Astronomy, Interdisciplinary Nanoscience Center (iNANO), Aarhus University, 8000 Aarhus C, Denmark — 4MAX IV Laboratory, Lund University, P.O. Box 118, 221 00 Lund, Sweden
Contrary to the case of Graphene's pi band structure, the deeper lying sigma bands have attracted little attention. Here we present a detailed study of the sigma band structure using angle resolved photoemission spectroscopy (ARPES). Graphene is prepared on different substrates and it is compared with graphite and quasi free standing graphene (graphene which is lifted up by oxygen intercalation after growth on Ir(111)). We find that such bands hide an unexpected large interaction close to the Gamma-bar point. A 'kink' deviates the band from the expected dispersion of a non-interacting band, and a corresponding broadening of the line width is seen. The experiment is supported by a numerical simulation of the many-body interaction, such that the nature of the kink can be probed. We conclude that electron phonon coupling plays a significant role and can satisfactorily account for the observed strong kink.