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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 [1], 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) [2]. 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) [3].

[1] C. Busse, P. Lazić, 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)

[2] 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)

[3] 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)