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Does filling-dependent band renormalization aid pairing in twisted bilayer graphene?

Lewandowski, Cyprian and Nadj-Perge, Stevan and Chowdhury, Debanjan (2021) Does filling-dependent band renormalization aid pairing in twisted bilayer graphene? . (Submitted)

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Twisted bilayer graphene exhibits a panoply of many-body phenomena that are intimately tied to the appearance of narrow and well isolated electronic bands near magic-angle. The microscopic ingredients that are responsible for the complex experimental phenomenology include electron-electron (phonon) interactions and non-trivial Bloch wavefunctions associated with the narrow bands. Inspired by recent experiments, we focus here on an interplay of two independent interaction-induced phenomena on superconductivity. We analyze the combined effects of Coulomb interaction driven band-flattening and phonon-mediated attraction due to the exchange of multiple electron-phonon umklapp processes, as a function of filling and twist angle. The former leads to a filling-dependent enhancement of the renormalized density of states, which contributes to a robust increase in the tendency towards pairing in a range of angles near magic-angle. In addition, the minimal spatial extent associated with the Wannier functions develops a non-trivial enhancement as a result of these many-body renormalizations, which can further contribute towards stabilizing the superconducting state over a wider range of fillings and twist-angles.

Item Type:Report or Paper (Discussion Paper)
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URLURL TypeDescription Paper
Lewandowski, Cyprian0000-0002-6944-9805
Nadj-Perge, Stevan0000-0002-2916-360X
Additional Information:Attribution 4.0 International (CC BY 4.0). We thank Jason Alicea, Erez Berg and Johannes Hofmann for useful discussions and Jonathan Ruhman for an earlier collaboration. C.L. acknowledges support from the Gordon and Betty Moore Foundation through Grant GBMF8682. S.N-P. acknowledges support from NSF (DMR-1753306), the Sloan Foundation, and the Institute for Quantum Information and Matter, an NSF Physics Frontiers Center with support of the Gordon and Betty Moore Foundation through Grant GBMF1250. D.C. is supported by a faculty startup grant at Cornell University.
Group:Institute for Quantum Information and Matter
Funding AgencyGrant Number
Gordon and Betty Moore FoundationGBMF8682
Alfred P. Sloan FoundationUNSPECIFIED
Institute for Quantum Information and Matter (IQIM)UNSPECIFIED
Gordon and Betty Moore FoundationGBMF1250
Cornell UniversityUNSPECIFIED
Record Number:CaltechAUTHORS:20210316-084002156
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:108448
Deposited By: Tony Diaz
Deposited On:19 Mar 2021 00:38
Last Modified:19 Mar 2021 00:38

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