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DF: Fachverband Dielektrische Festkörper

DF 10: Dielectric surfaces and interfaces

DF 10.3: Talk

Wednesday, April 2, 2014, 10:10–10:30, GER 37

Dielectric screening of surface states in a topological insulator — •James LeBlanc¹ and Jules Carbotte² — ¹Max-Planck Institute for the Physics of Complex Systems, Dresden DE — ²McMaster University, Hamilton Canada

Hexagonal warping provides an anisotropy to the dispersion curves of the helical Dirac fermions that exist at the surface of a topological insulator. We show how modifications to the Dirac spectrum by inclusion of hexagonal warping, as well as a Schrödinger and gap term modify the polarization function of the surface states. We derive in the long wavelength limit the plasmon dispersion and show that it obtains a weak dependence on the direction of scattering momentum, q. Further, we show numerically the plasmon dispersions at large q and find considerable directional anisotropy of the plasmon bands in comparison to the pure Dirac plasmons.