Condensed Matter Physics Seminar
Dr Carsten Busse, University of Cologne
Friday 14 June 2013, 1300-1400
C1 Physics Building
Geometric and electronic structure of graphene on Ir(111)
Graphene (gr) grown epitaxially on metal surfaces can be used as a model system to study fundamental properties of this new material using surface science methods. Here, the system of gr/Ir(111) is of special importance as the interaction between the carbon atoms and the substrate is weak , leaving the electronic structure largely identical to the one of free graphene. Furthermore, the carbon sheet can be grown as an extended layer of high structural quality.
In this talk, I will present a detailed study on the binding mechanism between graphene and its substrate based on x-ray standing wave (XSW) measurements corroborated with extended density functional theory calculations (DFT). In addition, I will present two strategies to modify the interaction of graphene with its substrate: The embedding (intercalation) of additional species between the carbon sheet and the metal surface weakens the binding significantly and potentially leads to a complete electronic decoupling for the case of gr/O/Ir(111) and allows mechanical exfoliation for the case of gr/Br/Ir(111) . Purposefully creating defects in the graphene sheet using ion bombardment leads to funnel-shape vacancy clusters where the broken C-C bonds saturate by binding to the metal. By tuning the balance between defect creation, annihilation, and migration, we were able to create a periodic pattern of holes in the graphene (nanomesh) .
 C. Busse, P. Lazi?, R. Djemour, J. Coraux, T. Gerber, N. Atodiresei, V. Caciuc, R. Brako, A. T. N'Diaye, S. Blügel, J. Zegenhagen, T. Michely, Phys. Rev. Lett. 107, 036101 (2011)
 C. Herbig, M. Kaiser, N. Bendiab, J. Coraux, S. Schumacher, D. F. Förster, K. Meerholz, T. Michely, C. Busse, J. Phys. Condens. Mat. 24, 314208 (2012)
 S. Standop, O. Lehtinen, C. Herbig, G. Lewes-Malandrakis, F. Craes, J. Kotakoski, T. Michely, A. V. Krasheninnikov, C. Busse, Nano Lett., DOI: 10.1021/nl304569n (2013)