Regensburg 2010 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 62: Graphene III
O 62.5: Vortrag
Donnerstag, 25. März 2010, 11:30–11:45, H31
Graphene on Ir(111): A tensile structure — •Carsten Busse1, Predrag Lazić2, Rabia Djemour1, Johann Coraux3, Timm Gerber1, Nicolae Atodiresei2, Vasile Caciuc2, Alpha T. N’Diaye1, Sven Runte1, Stefan Blügel3, Jörg Zegenhagen4, and Thomas Michely1 — 1II. Physikalisches Institut, Universität zu Köln, Germany — 2Institut für Festkörperforschung, Forschungszentrum Jülich, Germany — 3Institut Néel / CNRS-UJF, Grenoble, France — 4ESRF, Grenoble, France
Epitaxial growth on metal surfaces is an established method to produce highly ordered, extended graphene sheets. Ir(111) stands out from other substrates as the graphene grown on it is of extraordinary structural quality, shows an electronic structure almost equivalent to the one of free graphene, and can serve as a template for the growth of ordered superlattices of metal clusters.
Here we report measurements of the structure of graphene / Ir(111) based on X-ray standing waves (XSW), density functional theory (DFT) and scanning tunneling microscopy (STM). XSW reveals a bonding distance of (3.42 ± 0.02) Å between graphene and the substrate. This height can be accurately confirmed in DFT if Van-der-Waals-interaction is taken into account. STM experiments show that due to the mismatch of graphene and Ir(111) an incommensurate moiré pattern is formed. The chemical interaction between C and Ir as determined by DFT is attractive only in some regions of the superstructure, whereas it is even repulsive for other parts. This is the reason for the significant corrugation of the graphene.