Berlin 2012 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 83: [TT] Transport: Graphene 2 (jointly with MA, HL, DY, DS, O)
O 83.6: Vortrag
Freitag, 30. März 2012, 10:45–11:00, BH 334
Dielectric properties of graphene in the presence of spin-orbit interactions — •Andreas Scholz1, John Schliemann1, and Tobias Stauber2 — 1Institute for Theoretical Physics, University of Regensburg, 93040 Regensburg, Germany — 2Departamento de Fisica de la Materia Condensada and Instituto Nicolas Cabrera, Universidad Autonoma de Madrid. E-28049 Madrid. Spain
We study the dielectric function of graphene in the presence of pseudo-Rashba and intrinsic spin-orbit interactions (SOI) for arbitrary frequency, wave vector, doping, and spin-orbit coupling (SOC) parameters. In the static limit, the asymptotic behavior of the screened potential due to charged and magnetic impurities is derived. Due to the existence of a sharp Fermi surface in doped graphene, the screened potential exhibits characteristic (Friedel) oscillations. These oscillations are absent in the undoped case. An analytical expression for the plasmon dispersion is derived from the long-wavelength limit of the dielectric function and afterwards compared to the numerical result. For finite SOC parameters we find the existence of several new plasmon modes. Several limiting cases, namely the case of pure Rashba or pure intrinsic SOC, the case of equally large Rasbha and intrinsic coupling and of zero SOC are opposed.