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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 (2021) Shift-current response as a probe of quantum geometry and electron-electron interactions in twisted bilayer graphene. . (Unpublished)

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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 non-linear 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 wavefunctions 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: the mean energy of direct transitions between the hole and electron flat bands, and the gap between flat and dispersive bands. Including electron-electron interactions, both enhance the response at the non-interacting characteristic frequencies as well as produce new resonances. We attribute these changes to the filling-dependent band renormalization in TBG. Our results highlight the connection between non-trivial geometric properties of TBG and its optical response, as well as demonstrate how optical probes can access the role of interactions in moiŕe materials.

Item Type:Report or Paper (Discussion Paper)
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URLURL TypeDescription Paper
Lewandowski, Cyprian0000-0002-6944-9805
Additional Information:Attribution 4.0 International (CC BY 4.0) 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 desc0019166. GR is also grateful to the NSF DMR grant number 1839271. C.L. acknowledges support from the Gordon and Betty Moore Foundation through Grant GBMF8682.
Group:Institute for Quantum Information and Matter
Funding AgencyGrant Number
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
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:30 Aug 2021 17:23

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