The Ground State of Monolayer Graphene in a Strong Magnetic Field

• Published in: Scientific reports Vol. 6; no. 1; p. 22423
• Main Authors: Wu, Lian-Ao, Guidry, Mike
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 01.03.2016
• Subjects: Conductivity; Physics; Symmetry
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep22423

Experiments indicate that the ground state of graphene in a strong magnetic field exhibits spontaneous breaking of SU(4) symmetry. However, the nature of the corresponding emergent state is unclear because existing theoretical methods approximate the broken-symmetry solutions, yielding nearly-degenerate candidate ground states having different emergent orders. Resolving this ambiguity in the nature of the strong-field ground state is highly desirable, given the importance of graphene for both fundamental physics and technical applications. We have discovered a new SO(8) symmetry that recovers standard graphene SU(4) quantum Hall physics, but predicts two new broken-SU(4) phases and new properties for potential ground states. Our solutions are analytical; thus we capture the essential physics of spontaneously-broken SU(4) states in a powerful yet solvable model useful both in correlating existing data and in suggesting new experiments.