Berlin 2012 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 81: Graphene: Transport incl. Spin Physics and Magnetic Fields I

HL 81.3: Vortrag

Donnerstag, 29. März 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