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Shift-current response as a probe of quantum geometry and electron-electron interactions in twisted bilayer graphene

Chaudhary, Swati and Lewandowski, Cyprian and Refael, Gil (2022) Shift-current response as a probe of quantum geometry and electron-electron interactions in twisted bilayer graphene. Physical Review Research, 4 (1). Art. No. 013164. ISSN 2643-1564. doi:10.1103/PhysRevResearch.4.013164.

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Moiré materials, and in particular twisted bilayer graphene (TBG), exhibit a range of fascinating phenomena that emerge from the interplay of band topology and interactions. We show that the nonlinear second-order photoresponse is an appealing probe of this rich interplay. A dominant part of the photoresponse is the shift current, which is determined by the geometry of the electronic wave functions and carrier properties and thus becomes strongly modified by electron-electron interactions. We analyze its dependence on the twist angle and doping and investigate the role of interactions. In the absence of interactions, the response of the system is dictated by two energy scales: (i) the mean energy of direct transitions between the hole and electron flat bands and (ii) the gap between flat and dispersive bands. Including electron-electron interactions both enhances the response at the noninteracting characteristic frequencies and produces new resonances. We attribute these changes to the filling-dependent band renormalization in TBG. Our results highlight the connection between nontrivial geometric properties of TBG and its optical response, as well as demonstrate how optical probes can access the role of interactions in moiré materials.

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Lewandowski, Cyprian0000-0002-6944-9805
Additional Information:© 2022 Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Received 2 August 2021; revised 10 January 2022; accepted 27 January 2022; published 28 February 2022. We thank Stevan Nadj-Perge for an earlier collaboration and useful discussions. We acknowledge support from the Institute of Quantum Information and Matter, an NSF Physics Frontiers Center funded by the Gordon and Betty Moore Foundation, the Packard Foundation, and the Simons Foundation. G.R. and S.C. are grateful for support from the U.S. Department of Energy, Office of Science, Basic Energy Sciences, under Award No. desc0019166. G.R. is also grateful to NSF DMR Grant No. 1839271. C.L. acknowledges support from the Gordon and Betty Moore Foundation through Grant No. GBMF8682.
Group:Institute for Quantum Information and Matter
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Institute for Quantum Information and Matter (IQIM)UNSPECIFIED
Gordon and Betty Moore FoundationGBMF8682
David and Lucile Packard FoundationUNSPECIFIED
Simons FoundationUNSPECIFIED
Department of Energy (DOE)DE-SC0019166
Issue or Number:1
Record Number:CaltechAUTHORS:20210825-184647720
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:110563
Deposited By: George Porter
Deposited On:30 Aug 2021 17:23
Last Modified:19 Apr 2022 18:20

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