Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 22: Graphene: Structure and Theory II
HL 22.6: Vortrag
Montag, 26. März 2012, 18:30–18:45, EW 201
Density Oscillations in a Graphene Bilayer — •Nicolas Klier, Sam Shallcross, and Oleg Pankratov — Theoretische Festkörperphysik, Universität Erlangen, Staudtstr. 7B2, 91058 Erlangen
Density oscillations due to an impurity in graphene (Friedel oscillations) show a remarkable 1/r decay due to intervalley interference (1/r2 is the expected envelope form for a two dimensional e-gas) [1]. In this work we describe Friedel oscillations in Bernal, AA, and twist graphene bilayers. We consider an ideal δ-function impurity in conjunction with a low energy Green’s function of the bilayer system, and solve the Dyson equation exactly. We find that in addition to the Friedel oscilations in the local density of states, there is an additional long period modulation resulting from the interlayer coupling. Furthermore, we find the magnitude of such density oscillations are substantially increased near the Dirac point in Bernal stacked graphene as compared to single layer graphene.
[1] C. Bena, Phys. Rev. Lett., 100, 076601 (2008)