F55.00011. SU(3) fermions in a three-band graphene-like model

Presented by: Ankur Das


Two-dimensional graphene is fascinating because of its unique electronic properties. From a fundamental perspective, one among them is the geometric phase structure near the Dirac points in the Brillouin zone, owing to the SU(2) nature of the Dirac cone wave functions. We ask if there are geometric phase structures in two dimensions that go beyond that of a Dirac cone. Here we write down a family of three-band continuum models of noninteracting fermions that have more intricate geometric phase structures. This is connected to the SU(3) nature of the wave functions near threefold degeneracies. We also give a tight-binding free fermion model on a two-dimensional graphene-like lattice where the threefold degeneracies are realized at fine-tuned points. Away from them, we obtain new “three-band” Dirac cone structures with associated nonstandard Landau level quantization, whose organization is strongly affected by the non-SU(2) or beyond-Dirac geometric phase structure of the fine-tuned points.\r\n*NSF DMR1056536\r\nIRCC, IIT Bombay (17IRCCSG011)\r\nNSF DMR-1611161\r\nNSF DMR-1306897\r\nInternational Center for Theoretical Sciences (ICTS) during a visit for participating in the program The 2nd Asia Pacific Workshop on Quantum Magnetism (Code: ICTS/apfm2018/11)


  • Ankur Das
  • Sumiran Pujari


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