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arXiv · 2402.11824

Moir\'{e} optical phonons dancing with heavy electrons in magic-angle twisted bilayer graphene

Hao Shi·Wangqian Miao·Xi Dai
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Abstract

Electron-phonon coupling in magic-angle twisted bilayer graphene is an important but difficult topic. We propose a scheme to simplify and understand this problem. Weighted by the coupling strength with the low-energy heavy electrons ($f$ orbitals), several moir\'{e} optical phonons are singled out which strongly couple to the flat bands. These modes have localized envelopes in the moir\'{e} scale, while in the atomic scale they inherit the monolayer oscillations like the Kekul\'{e} pattern. They flip the flavor of $f$ orbitals, helping stabilize some symmetry-breaking orders. Such electron-phonon couplings are incorporated into an effective extended Holstein model, where both phonons and electrons are written as moir\'{e} scale basis. We hope this model will inspire some insights guiding further studies about the superconductivity and other correlated effects in this system.

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Hao Shi, Wangqian Miao, Xi Dai. 2024-02-19. Moir\'{e} optical phonons dancing with heavy electrons in magic-angle twisted bilayer graphene. https://doi.org/10.1103/physrevb.111.155126

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