Otteneder, Maximilian and Hubmann, Stefan and Lu, Xiaobo and Kozlov, Dmitry A. and Golub, Leonid E. and Watanabe, Kenji and Taniguchi, Takashi and Efetov, Dmitri K. and Ganichev, Sergey D. (2020) Terahertz Photogalvanics in Twisted Bilayer Graphene Close to the Second Magic Angle. NANO LETTERS, 20 (10). pp. 7152-7158. ISSN 1530-6984, 1530-6992
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We report on the observation of photogalvanic effects in tBLG with a twist angle of 0.6 degrees. We show that excitation of the tBLG bulk causes a photocurrent, whose sign and magnitude are controlled by the orientation of the radiation electric field and the photon helicity. The observed photocurrent provides evidence for the reduction of the point group symmetry in low twist-angle tBLG to the lowest possible one. The developed theory shows that the current is formed by asymmetric scattering in gyrotropic tBLG. We also detected the photogalvanic current formed in the vicinity of the edges. For both bulk and edge photocurrents, we demonstrate the emergence of pronounced oscillations upon variation of the gate voltage. The gate voltages associated with the oscillations correlate with peaks in resistance measurements. These are well explained by interband transitions between a multitude of isolated bands in tBLG.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | ; twisted graphene; terahertz radiation; photogalvanics |
| Subjects: | 500 Science > 530 Physics |
| Divisions: | Physics > Institute of Experimental and Applied Physics > Professor Ganichev > Group Sergey Ganichev |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 09 Mar 2021 06:18 |
| Last Modified: | 09 Mar 2021 06:18 |
| URI: | https://pred.uni-regensburg.de/id/eprint/43562 |
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