Unconventional Superconductivity and Density Waves in Twisted Bilayer Graphene

By H. Isobe, N. Yuan, Liang Fu. Physical Review X, 2018

302 citations recorded by the source corpus.

We study electronic ordering instabilities of twisted bilayer graphene with $n=2$ electrons per supercell, where correlated insulator state and superconductivity are 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 renormalization group method, we find $d$/$p$-wave superconductivity and charge/spin density wave emerge as the two types of leading instabilities driven by Coulomb repulsion. The density wave state has a gapped energy spectrum at $n=2$ 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.

Subfields: Atomic and Molecular Physics, and Optics, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/24e0d78a27b813e9e1a9b40e0c8bc1f101ce24c0

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In Atomic and Molecular Physics, and Optics

In Materials Chemistry

Citations in the corpus

Symmetry-broken Chern insulators and Rashba-like Landau-level crossings in magic-angle bilayer graphene (2020, background): “1° (MATBG), ultra-flat moiré bands (1-6) host strongly interacting electrons which give rise to a plethora of phases including correlated insulators (CI)(1, 7-10), superconductors (SC)(2, 7, 11-21) and orbital magnets (OM)(7, 22-24).”