Electron-phonon coupling in the topological heavy fermion model of twisted bilayer graphene

Abstract

Plentiful strongly correlated electronic phases have been identified in magic-angle twisted bilayer graphene, yet the microscopic ingredients that stabilize them have remained elusive. This study demonstrates that the electron-phonon coupling (EPC), by introducing a significant multiplet splitting to the moir\'e-scale local orbitals, plays a vital role in determining these phases. The splitting not only selects the competing symmetry-breaking insulators, but also triggers the unconventional superconducting phase, and provides an alternative explanation to the semimetallic behavior at the charge neutrality point.