Berlin 2015 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 93: Graphen (organized by DS)
TT 93.4: Talk
Thursday, March 19, 2015, 10:15–10:30, H 0111
Investigation of atomic-scale strain variations in graphene as a function of applied strain — •Stefan E. Huber1, Gerard Verbiest2, Christoph Stampfer2, and Karsten Reuter1 — 1Technische Universität München — 2RWTH Aachen
Graphene exhibits unique electronic and mechanical properties. The very high electron mobilities that can be reached in state-of-the-art devices suggest this material to revolutionize present-day electronics. The demand for high mobilities raises the question what actually limits these in graphene. Recent experiments provide evidence that most likely nanometer-scale strain variations are the mechanism responsible for the limitation of the charge carrier mobility [1,2].
Homogeneously straining graphene is expected to reduce local strain fluctuations and thus to increase the electron mobility. We address this issue with atomistic simulations of two distinct mechanisms that may give rise to nanometer-scale strain variations in the presence of overall strain. Using (and comparing) a series of interatomic potentials to describe graphene, we study (i) the effect of surface defects in a hexagonal boron-nitride substrate deduced from first-principles DFT calculations as well as (ii) thermally induced fluctuations. In both respects, we discuss the effective suppression of out-of-plane distortions already at moderate global strains of a few per cent. In stark contrast, in-plane deformations are enhanced upon the application of global strain, a result clearly beyond the limitations of linear elasticity theory.
[1] N.J.G. Couto et al., Phys. Rev. X 4, 041019 (2014)
[2] S. Engels et al., Phys. Rev. Lett. 113, 126801 (2014)