← Back to search

Unconventional Superconductivity and Density Waves in Twisted Bilayer Graphene

Hiroki Isobe, Noah F. Q. Yuan, Liang Fu

DOI 10.1103/PhysRevX.8.041041 · Physical Review X

T1

Active bibliographic source — not scientific approval

Bibliographic access preserves source history; it does not approve extracted materials or validate reported claims. Review warnings on each occurrence separately.

Abstract

We study electronic ordering instabilities of twisted bilayer graphene around the filling of n=2 electrons per supercell, where correlated insulator state and superconductivity have been recently observed. Motivated by the Fermi surface nesting and the proximity to Van Hove singularity, we introduce a hot-spot model to study the effect of various electron interactions systematically. Using the renormalization group method, we find that d or p-wave superconductivity and charge or spin density wave emerge as the two types of leading instabilities driven by Coulomb repulsion. The density-wave state has a gapped energy spectrum around n=2 and yields a single doubly degenerate pocket upon doping to n>2. The intertwinement of density wave and superconductivity and the quasiparticle spectrum in the density-wave state are consistent with experimental observations.

Similar papers