Year: 2018
Type: article
Abstract: We study electronic ordering instabilities of twisted bilayer graphene around the filling of n ¼ 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 ¼ 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.
Source: Physical Review X
Authors: Hiroki Isobe, Noah F. Q. Yuan, Liang Fu
Institution: Massachusetts Institute of Technology
Language: English
Subfield: Condensed Matter Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $4,200
OpenAlex ID: W2822844445