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HL: Fachverband Halbleiterphysik

HL 81: Graphene: Transport

HL 81.4: Vortrag

Donnerstag, 17. März 2011, 15:15–15:30, POT 151

Dynamic Hall effect driven by circularly polarized light in graphene — •J. Karch¹, P. Olbrich¹, M. Schmalzbauer¹, C. Zoth¹, C. Brinsteiner¹, M. Fehrenbacher¹, U. Wurstbauer¹, M. M. Glazov², S. A. Tarasenko², E. L. Ivchenko², D. Weiss¹, J. Eroms¹, R. Yakimova³, S. Lara-Avila⁴, S. Kubatkin⁴, and S. D. Ganichev¹ — ¹Terahertz Center, Regensburg, Germany — ²Ioffe Institute, St. Petersburg, Russia — ³Linköping University, Linköping, Sweden — ⁴Chalmers University of Technology, Göteborg, Sweden

We report the observation of the circular ac Hall effect where the current is solely driven by the crossed ac electric and magnetic fields of circularly polarized radiation [1]. To demonstrate the existence of this effect we studied monolayer graphene sheets. We show that illuminating an unbiased sample with circularly polarized terahertz radiation at room temperature generates - under oblique incidence - an electric current perpendicular to the plane of incidence, whose sign is reversed by switching the radiation helicity. Alike the classical dc Hall effect, the voltage is caused by crossed electric and magnetic fields which are, however, rotating with the light’s frequency. The effect is studied in both exfoliated graphene on SiO₂ substrates and epitaxial samples thermally grown on SiC. The photocurrent experiments are carried out using a cw and a high power pulsed terahertz laser. Besides the circular ac Hall effect we observe helicity dependent currents at normal incidence stemming from the illumination of the graphene edges.

[1] J. Karch et al., Phys. Rev. Lett. 105, 227402 (2010).