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Dresden 2009 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 46: Electronic Properties II

MM 46.5: Vortrag

Donnerstag, 26. März 2009, 17:45–18:00, IFW B

Quantum effects on the Elasticity of Graphene: An ab-initio and tight binding study — •Soumya Bera1, Andreas Arnold1, and Ferdinand Evers1,21Institut für Nanotechnologie, Forschungszentrum Karlsruhe, D-76021 Karlsruhe, Germany — 2Institut für Theorie der Kondensierten Materie, Universität Karlsruhe, D-76128 Karlsruhe, Germany

One of the most interesting aspect of single layer graphene is its surface corrugation (ripples), which can either be intrinsic or induced by surface roughness of the substrate. The long wavelength elastic properties of this novel material are also of great interest and we investigate them here. Our focus is on elasticity in the presence of ripples. We are going to employ two distinct methods namely ab-initio and tight binding calculations, in order to study the effect of ripples together with there associated zero modes on elasticity.

Our ab-initio study supports the exceptional quadratic dispersion relation of flexural(out-of-plane) phonons which is imposed by the spatial symmetries in the long wavelength limit of elastic theory. While short wavelength optical phonons have been studied in the past, to the best of our knowledge our work is the first ab-initio study on the long wave-length context. This DFT analysis also suggests a considerable amount(∼ 4%) of change in elastic constants due to zero point motion of phonons originated from the in-plane strain in the system. Using a tight binding model with nearest neighbor hopping we are now exploring the impact of zero energy states on elasticity. Here the source of these zero energy states is strain, induced by ripples.

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