Dresden 2014 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 61: Graphene: Transport (organized by HL)
TT 61.2: Vortrag
Mittwoch, 2. April 2014, 09:45–10:00, POT 051
Magnetic quantum ratchet effect in graphene — •Christoph Drexler1, Sergey Tarasenko2, Peter Olbrich1, Johannes Karch1, Marion Hirmer1, Florian Müller1, Martin Gmitra1, Jaroslav Fabian1, Rositza Yakimova3, Samuel Lara-Avila4, Sergey Kubatkin4, Minjie Wang5, Junichiro Kono5, and Sergey Ganichev5 — 1THz Center, University of Regensburg, Germany — 2Ioffe Physical-Technical Institute, St. Petersburg, Russia — 3Linköping University, Sweden — 4Chalmers University, Göteborg, Sweden — 5Rice University, Houston, USA
We report on the experimental observation of the magnetic quantum ratchet effect in epitaxial- and CVD- grown graphene layers excited by pulsed terahertz (THz ) - laser radiation [1]. Our experimental findings can be well understood in terms of asymmetric carrier scattering in graphene in presence of an in-plane magnetic field yielding strong structure inversion asymmetry (SIA) in graphene. The SIA stems from the fact that graphene is deposited on a substrate and/or is sensitive to chemical bonding of adatoms on the surface. Considering hydrogen atoms on top of carbon we calculated the magnitude of the photocurrent being in good agreement with the data obtained from the experiments. The amplitudes of the current differ significantly for the used material systems whereas its sign can be influenced by the post-groth treatment of the samples. The ratchet current can be calibrated to measure the strength of the SIA, which plays an important role in graphene ferromagnetism and spintronics.
[1] C. Drexler et al, Nat. Nano. 8 104-107, 2013.