Dresden 2014 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 36: Posters: Bio/organic Molecules on Surfaces, Graphene, Solid/liquid interfaces, Metal Substrates, Electronic Structure Theory
O 36.47: Poster
Dienstag, 1. April 2014, 18:30–22:00, P1
Plasmons in graphene bilayers — •Phillipp Reck1, Sam Shallcross2, and Oleg Pankratov2 — 1Institut für Theoretische Physik, Universität Regensburg — 2Lehrstuhl für Theoretische Festkörperphysik, FAU Erlangen
Plasmons are the fundamental collective excitations in the electron system which underlie various many-body phenomena. In two dimensions, plasmons have a square root dispersion. For a double layer system an additional linear branch arises which features a finite gap at q=0 which is due to the interlayer tunneling [1]. Multilayer graphene stacks offer an interesting possibility for realizing such systems. Moreover, stacks with mutually rotated layers present a novel 2D system which is periodically modulated due to the moiré pattern [2]. It was found [3] that the moiré potential alters the one particle spectrum and induces Anderson-type localization at certain energies.
Our work aims at exploring the many-particle effects in these moiré systems, where at first we investigate plasmons in the RPA, using the low energy, homogeneous Mele Hamiltonians [4]. We find qualitatively the same results as in 2DEG. To include the inhomogeneity effects of the moiré potential we shall accordingly adopt the RPA scheme by including the most important coupling reciprocal vectors of the moiré periodicity [3].
[1] S. Das Sarma and E. H. Hwang, Phys. Rev. Lett. 81, 4216 (1998)
[2] S. Shallcross et al, PRB 81, 165105 (2010)
[3] S. Shallcross et al, PRB 87, 245403 (2013)
[4] E. J. Mele, PRB 81, 161405(R) (2010)