Berlin 2012 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 53: Graphene IV
O 53.3: Vortrag
Mittwoch, 28. März 2012, 17:15–17:30, MA 041
Theory of graphene-boron nitride heterostructures — •Burkhard Sachs1, Tim Wehling1, Mikhail Katsnelson2, and Alexander Lichtenstein1 — 11. Institut für Theoretische Physik, Universität Hamburg, Jungiusstraße 9, D-20355 Hamburg, Germany — 2Institute for Molecules and Materials, Radboud University Nijmegen, NL-6525 AJ Nijmegen, The Netherlands
We report theoretical investigations of graphene-boron nitride heterostructures [1]. In detail, we investigate the adsorption of graphene sheets on hexagonal boron nitride substrates by means of first-principles calculations in the framework of adiabatic connection fluctuation-dissipation theory in the random-phase approximation. We obtain adhesion energies for different crystallographic stacking configurations and show that the interlayer bonding is due to long-range van der Waals forces. The interplay of elastic and adhesion energies is shown to lead to stacking disorder and moiré structures. Band-structure calculations reveal substrate induced mass terms in graphene, which change their sign with the stacking configuration. The dispersion, absolute band gaps, and the real-space shape of the low-energy electronic states in the moiré structures are discussed. We find that the absolute band gaps in the moiré structures are at least an order of magnitude smaller than the maximum local values of the mass term. Our results are in agreement with recent scanning tunneling microscopy experiments.
[1] B. Sachs, T. O. Wehling, M. I. Katsnelson, and A. I. Lichtenstein, Phys. Rev. B 84, 195414 (2011)