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First-principles strategy for electron-phonon coupling in twisted bilayer graphene

ORAL

Abstract

Twisted bilayer graphene (tBLG) systems at certain twisted angles host exotic phenomena such as superconductivity and correlated insulator state. One key question is whether the superconductivity in such systems is phonon-driven or not. However, a moiré unit cell at small twisted angles usually contains over ten thousand of atoms, limiting any quantitative first-principles investigations on the electron-phonon (e-ph) coupling in tBLG. Here we propose a first-principles strategy to accurately compute the e-ph coupling in tBLG where the e-ph matrix elements in the moiré cells are mapped to those in few-atom unit-cells, with controlled approximations. The e-ph coupling is computed using density-functional perturbation theory and GW perturbation theory [1], with the latter includes electron correlation effects in the e-ph matrix elements. This strategy can be generalized to other interactions in different moiré systems while incorporating both intralayer and interlayer effects.

[1] Z. Li, G. Antonius, M. Wu, F. H. da Jornada, and S. G. Louie, Phys. Rev. Lett. 122, 186402 (2019).

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Presenters

  • Zhenglu Li

    Department of Physics, University of California, Berkeley, UC Berkeley & Lawrence Berkeley National Laboratory, University of California at Berkeley, and Lawrence Berkeley National Laboratory, University of California at Berkeley and Lawrence Berkeley National Laboratory, Lawrence Berkeley National Laboratory, University of California, Berkeley, Lawrence Berkeley National Laboratory and University of California at Berkeley, Department of physics, University of California at Berkeley, Berkeley, California

Authors

  • Zhenglu Li

    Department of Physics, University of California, Berkeley, UC Berkeley & Lawrence Berkeley National Laboratory, University of California at Berkeley, and Lawrence Berkeley National Laboratory, University of California at Berkeley and Lawrence Berkeley National Laboratory, Lawrence Berkeley National Laboratory, University of California, Berkeley, Lawrence Berkeley National Laboratory and University of California at Berkeley, Department of physics, University of California at Berkeley, Berkeley, California

  • Mit Naik

    Department of Physics, University of California at Berkeley, University of California at Berkeley and Lawrence Berkeley National Laboratory, Department of physics, University of California at Berkeley, Berkeley, California

  • Yang-hao Chan

    Lawrence Berkeley National Laboratory, University of California at Berkeley and Lawrence Berkeley National Laboratory, University of California, Berkeley, Department of physics, University of California at Berkeley, Berkeley, California

  • Meng Wu

    University of California at Berkeley and Lawrence Berkeley National Laboratory, University of California, Berkeley

  • Steven G Louie

    University of California, Berkeley, Department of Physics, University of California, Berkeley, University of California at Berkeley and Lawrence Berkeley National Laboratory, UC Berkeley & Lawrence Berkeley National Laboratory, University of California at Berkeley, and Lawrence Berkeley National Laboratory, Lawrence Berkeley National Laboratory, Department of physics, University of California at Berkeley, Berkeley, California