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Correlation-driven super Van Hove singularity in slow graphene

ORAL

Abstract

High-order Van Hove singularities (VHSs) provide a novel mechanism for driving strong electron correlation effects in materials such as the super-metallic state. We show how such VHSs emerge in the paradigmatic family of slow graphenes to produce the excitonic insulator (EI) state. Our systematic analysis reveals a crossover from a weak to a strong electron-correlation regime, which is triggered when velocity of the Dirac carriers is reduced through a renormalization of their bandwidth. The resulting flattening of the edges of the conduction and valence bands yields QΓ = (0, 0) and QM = (π, 0) excitons and produces correlation-driven high-order VHSs with power-law divergences in the density-of-states. Our study indicates that a variety of 2D materials beyond the twisted bilayer graphene would provide viable single-phase material platforms for exploring the physics of high-order VHSs and how these VHSs drive exciting correlation-driven phenomena in quantum matter.

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Presenters

  • Baokai Wang

    Department of Physics, Northeastern University, Northeastern University, Department of Physics, Northeastern University, USA

Authors

  • Baokai Wang

    Department of Physics, Northeastern University, Northeastern University, Department of Physics, Northeastern University, USA

  • Bahadur Singh

    Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Department of Condensed Matter Physics and Material Science, Tata Institute of Fundamental Research, Tata Institute of Fundamental Research, Tata Institute for Fundamental Research, DCMPMS, Tata Institute of Fundamental Research, India, Condensed Matter Physics and Material Science, Tata Institute of Fundamental Research, Department of Condensed Matter Physics & Materials Science, Tata Institute of Fundamental Research

  • Hsin Lin

    Institute of Physics, Academia Sinica, Academia Sinica, Institute of Physics, Academia Sinica, Taipei, Institute of Physics, Academia Sinica, Taiwan, Physics, Academia Sinica

  • Robert Markiewicz

    Northeastern University, NU, Northeastern U

  • Arun Bansil

    Department of Physics, Northeastern University, Northeastern University, NU, Department of Physics, Northeastern University, USA