Abstract-Edge currents driven by terahertz radiation in graphene in quantum Hall regime

Helene Plank, M V Durnev, Susanne Candussio, Johanna Pernul, Kathrin-Maria Dantscher, Erwin Mönch, Andreas Sandner, Jonathan Eroms, Dieter Weiss, Vasily V Belkov

http://iopscience.iop.org/article/10.1088/2053-1583/aae39c

We observe that the illumination of  graphene in the quantum Hall regime with polarized terahertz laser radiation results in a direct edge current. This photocurrent is caused by an imbalance of persistent edge currents, which are driven out of thermal equilibrium by indirect transitions within the chiral edge channel. The direction of the edge photocurrent is determined by the polarity of the external magnetic field, while its magnitude depends on the radiation polarization. The microscopic theory developed in this paper describes well the experimental data.

Abstract-Terahertz electric field driven electric currents and ratchet effects in graphene

Sergey D. Ganichev, Dieter Weiss, Jonathan Eroms

(Submitted on 17 Oct 2017)

https://arxiv.org/abs/1710.06243#

Terahertz field induced photocurrents in graphene were studied experimentally and by microscopic modeling. Currents were generated by cw and pulsed laser radiation in large area as well as small-size exfoliated graphene samples. We review general symmetry considerations leading to photocurrents depending on linear and circular polarized radiation and then present a number of situations where photocurrents were detected. Starting with the photon drag effect under oblique incidence, we proceed to the photogalvanic effect enhancement in the reststrahlen band of SiC and edge-generated currents in graphene. Ratchet effects were considered for in-plane magnetic fields and a structure inversion asymmetry as well as ratchets by non-symmetric patterned top gates. Lastly, we demonstrate that graphene can be used as a fast, broadband detector of terahertz radiation.