Abstract-Observation of terahertz-induced magnetooscillations in graphene

Erwin Mönch, Denis A. Bandurin, Ivan A. Dmitriev, Isabelle Y. Phinney, Ivan Yahniuk, Takashi Taniguchi, Kenji Watanabe, Pablo Jarillo-Herrero, Sergey D. Ganichev

https://pubs.acs.org/doi/pdf/10.1021/acs.nanolett.0c01918#

When high-frequency radiation is incident upon graphene subjected to a perpendicular magnetic field, graphene absorbs incident photons by allowing transitions between nearest LLs that follow strict selection rules dictated by angular momentum conservation. Here we show a qualitative deviation from this behavior in high-quality graphene devices exposed to terahertz (THz) radiation. We demonstrate the emergence of a pronounced THz-driven photoresponse, which exhibits low-field magnetooscillations governed by the ratio of the frequency of the incoming radiation and the quasiclassical cyclotron frequency. We analyze the modifications of generated photovoltage with the radiation frequency and carrier density and demonstrate that the observed photoresponse shares a common origin with microwave-induced resistance oscillations previously observed in GaAs-based heterostructures, yet in graphene, it appears at much higher frequencies and persists above liquid nitrogen temperatures. Our observations expand the family of radiation-driven phenomena in graphene, paving the way for future studies of nonequilibrium electron transport.

Abstract-Observation of terahertz-induced magnetooscillations in graphene

Erwin Mönch, Denis A. Bandurin, Ivan A. Dmitriev, Isabelle Y. Phinney, Ivan Yahniuk, Takashi Taniguchi, Kenji Watanabe, Pablo Jarillo-Herrero, Sergey D. Ganichev

https://arxiv.org/abs/2005.01118

When high-frequency radiation is incident upon graphene subjected to a perpendicular magnetic field, graphene absorbs incident photons by allowing transitions between nearest LLs that follow strict selection rules dictated by angular momentum conservation. Here we show a qualitative deviation from this behavior in high-quality graphene devices exposed to terahertz (THz) radiation. We demonstrate the emergence of a pronounced THz-driven photoresponse, which exhibits low-field magnetooscillations governed by the ratio of the frequency of the incoming radiation and the quasiclassical cyclotron frequency. We analyze the modifications of generated photovoltage with the radiation frequency and carrier density and demonstrate that the observed photoresponse shares a common origin with microwave-induced resistance oscillations previously observed in GaAs-based heterostructures, yet in graphene, it appears at much higher frequencies and persists above liquid nitrogen temperatures. Our observations expand the family of radiation-driven phenomena in graphene and offer potential for the development of novel optoelectronic devices.

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.