Unconventional Superconductivity and Density Waves in Twisted Bilayer Graphene
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...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
American Physical Society,
2018-12-20T20:13:12Z.
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| Subjects: | |
| Online Access: | Get fulltext |
| Summary: | 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. Subject Areas: Condensed Matter Physics, Superconductivity United States. Department of Energy. Division of Materials Sciences and Engineering (Award DE-SC0010526) David & Lucile Packard Foundation |
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