Kohn-Luttinger Superconductivity in Twisted Bilayer Graphene

J. González and T. Stauber
Phys. Rev. Lett. 122, 026801 – Published 18 January 2019
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Abstract

We show that the recently observed superconductivity in twisted bilayer graphene (TBG) can be explained as a consequence of the Kohn-Luttinger (KL) instability which leads to an effective attraction between electrons with originally repulsive interaction. Usually, the KL instability takes place at extremely low energy scales, but in TBG, a doubling and subsequent strong coupling of the van Hove singularities (vHS) in the electronic spectrum occurs as the magic angle is approached, leading to extended saddle points in the highest valence band with almost perfect nesting between states belonging to different valleys. The highly anisotropic screening induces an effective attraction in a p-wave channel with odd parity under the exchange of the two disjoined patches of the Fermi line. We also predict the appearance of a spin-density wave instability, adjacent to the superconducting phase, and the opening of a gap in the electronic spectrum from the condensation of spins with wave vector corresponding to the nesting vector close to the vHS.

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  • Received 2 July 2018

DOI:https://doi.org/10.1103/PhysRevLett.122.026801

© 2019 American Physical Society

Physics Subject Headings (PhySH)

  1. Physical Systems
  1. Techniques
Condensed Matter, Materials & Applied Physics

Authors & Affiliations

J. González1 and T. Stauber2

  • 1Instituto de Estructura de la Materia, CSIC, E-28006 Madrid, Spain
  • 2Materials Science Factory, Instituto de Ciencia de Materiales de Madrid, CSIC, E-28049 Madrid, Spain

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Issue

Vol. 122, Iss. 2 — 18 January 2019

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