Dresden 2014 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 61: Graphene: Transport (organized by HL)
TT 61.1: Talk
Wednesday, April 2, 2014, 09:30–09:45, POT 051
Ratchet effects in graphene with a lateral potential — •Josef Kamann1, Leonid Golub2, Matthias König1, Jonathan Eroms1, Felix Fromm3, Thomas Seyller3, Dieter Weiss1, and Sergey Ganichev1 — 1University of Regensburg, Germany — 2Ioffe Physical-Technical Institute of the RAS, St. Petersburg, Russia — 3Technical University of Chemnitz, Germany
We report on the observation of terahertz radiation induced ratchet effects in graphene with a lateral periodic potential. These effects generate a dc electric current from an ac electric field. To probe ratchet effects, a metal grating has been deposited on top of epitaxially grown graphene. This lattice contains periodically deposited stripes with different widths and spaces and, therefore, has no inversion symmetry.
We demonstrate that the ratchet effect is generated only in the modulated area and does not arise in unpatterned graphene. This proves the symmetry breaking induced by the asymmetric lateral potential. Additional effects like edge currents or the circular ac Hall effect are excluded by the geometry of the samples and by illumination under normal incidence. The ratchet signal is studied with respect to the polarization and the wavelength of the radiation. We show that the ratchet effect is sensitive to both linear and circular polarization and conducted calculations for different elastic-scattering processes to compare them to our experimental findings.