Dresden 2009 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 26: Poster II

DY 26.27: Poster

Donnerstag, 26. März 2009, 16:00–18:00, P1A

Semiclassical Theory for Graphene Flakes — •Jürgen Wurm, Klaus Richter, and Inanc Adagideli — Institut für Theoretische Physik, Universität Regensburg, 93040 Regensburg

Motivated by the recently increased experimental activity [1-2], we study graphene quantum dot systems theoretically. In previous work, we explored the effect of boundary conditions on the transport and spectral properties of graphene quantum dots numerically [3]. In this work, we seek an analytic approach. To this end, we derive a multiple reflection expansion for the exact Green function of the effective Dirac equation for a graphene flake with a general boundary. Here we take into account contributions from both valleys, thus dealing with 4x4 (pseudo-)spin matrices. Evaluating this Green function semiclassically, we obtain a sum over classical multiple reflection paths. The advantage of this approach is the natural incorporation of the boundary conditions at the flake's edges. Using the semiclassical graphene Green function, we then investigate quantum transport, e.g. weak localization effects, as well as the semiclassical density of states in terms of a Dirac version of the Gutzwiller trace formula.

[1] L.A. Ponomarenko, F. Schedin, M.I. Katsnelson, R. Yang, E.W. Hill, K.S. Novoselov, A.k. Geim, Science 320, 356 (2008)

[2] C. Stampfer, J. Guettinger, F. Molitor, D. Graf, T. Ihn, K. Ensslin, Appl. Phys. Lett. 92, 012102 (2008)

[3] J. Wurm, Adam Rycerz, Inanc Adagideli, M. Wimmer, K. Richter, H.U. Baranger, arXiv:0808.1008 (2008)