Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session P51: Graphene: Electronic Structure and Interactions: Moire patterns
2:30 PM–5:30 PM,
Wednesday, March 4, 2020
Room: Mile High Ballroom 1D
Sponsoring
Units:
DCMP DMP
Chair: Emilio Codecido, Ohio State Univ - Columbus
Abstract: P51.00002 : Chiral twist on the high-Tc phase diagram in moiré heterostructures*
Presenter:
Yu-Ping Lin
(Department of Physics, University of Colorado, Boulder)
Authors:
Yu-Ping Lin
(Department of Physics, University of Colorado, Boulder)
Rahul Nandkishore
(Department of Physics, University of Colorado, Boulder)
We show that the large orbital degeneracy inherent in moiré heterostructures naturally gives rise to a 'high-Tc' like phase diagram with a chiral twist - wherein an exotic quantum anomalous Hall insulator is flanked by chiral d+id superconducting domes. Specifically, we analyze repulsively interacting fermions on hexagonal lattices near Van Hove filling, with an SU(4) flavor degeneracy. At this point, a nested Fermi surface and divergent density of states give rise to strong ln2 instabilities to correlated phases, the competition between which can be controllably addressed through a combination of weak coupling parquet renormalization group and Landau-Ginzburg analysis. We uncover an unambiguous and rich behavior, wherein at weak coupling the leading instability is to a Chern insulator, characterized by a spontaneous breaking of time reversal symmetry and a quantized Hall response. Upon doping this phase gives way to a chiral d+id superconductor. We further consider deforming this minimal model by an orbital splitting, and discuss the resulting RG flow and phase diagram. Our analysis thus bridges the minimal model and the practical moiré bands, thereby elucidates transparently how the correlated phases arise.
*Supported by the Army Research Office under Grant No. W911NF-17-1-0482.
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