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HL: Fachverband Halbleiterphysik
HL 81: Graphene: Transport incl. Spin Physics and Magnetic Fields I
HL 81.3: Talk
Thursday, March 29, 2012, 15:30–15:45, ER 270
Terahertz radiation driven chiral edge currents in graphene — •C. Drexler1, J. Karch1, P. Olbrich1, M. Fehrenbacher1, M. Hirmer1, M. M. Glazov2, S. A. Tarasenko2, B. Birkner1, J. Eroms1, D. Weiss1, R. Yakimova3, S. Lara-Avila4, S. Kubatkin4, M. Ostler5, T. Seyller5, E. L. Ivchenko2, and S. D. Ganichev1 — 1Terahertz Center, Regensburg, Germany — 2Ioffe Institute, St. Petersburg, Russia — 3Linköping University, Linköping, Sweden — 4Chalmers University of Technology, Göteborg, Sweden — 5University of Erlangen-Nürnberg, Erlangen, Germany
Here we report on photocurrents induced in single layer graphene samples by illumination of the graphene edges with circularly polarized terahertz radiation at normal incidence. The photocurrent flows along the sample edges and forms a vortex. Its winding direction reverses by switching the light helicity from left- to right-handed. We demonstrate that the effect is directly coupled to electron scattering at the graphene edge which reduces the spatial symmetry and vanishes in bulk graphene. The developed theory based on Boltzmann’s kinetic equation is in good agreement with the experimental findings. Our results suggest that the circular photocurrents can be effectively used to study edge transport in graphene even at room temperature.
[1] J. Karch et al, Phys. Rev. Lett. (in print); arXiv:1107.3747v1