Twisted Bilayer Graphene: A Phonon-Driven Superconductor

Biao Lian; Zhijun Wang; B. Andrei Bernevig

doi:10.1103/PhysRevLett.122.257002

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Twisted Bilayer Graphene: A Phonon-Driven Superconductor

Biao Lian, Zhijun Wang, B. Andrei Bernevig

DOI 10.1103/PhysRevLett.122.257002 · Physical Review Letters

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Abstract

We study the electron-phonon coupling in twisted bilayer graphene (TBG), which was recently experimentally observed to exhibit superconductivity around the magic twist angle θ≈1.05°. We show that phonon-mediated electron attraction at the magic angle is strong enough to induce a conventional intervalley pairing between graphene valleys K and K′ with a superconducting critical temperature Tc∼1 K, in agreement with the experiment. We predict that superconductivity can also be observed in TBG at many other angles θ and higher electron densities in higher moiré bands, which may also explain the possible granular superconductivity of highly oriented pyrolytic graphite. We support our conclusions by ab initio calculations.