Evolution from weak to strong coupling pairing of Dirac Fermions

ORAL

Abstract

We study the pairing of Dirac Fermions with attractive interaction from weak to strong coupling regime, highlighting the differences and resemblances with that of the BCS-BEC crossover in the systems with extended Fermi surface. Dirac Fermions model at low doping limit is solved by mean field approximation. Exact Quantum Monte Carlo method, auxiliary field Quantum Monte Carlo, is used to simulate the single band attractive Hubbard model on a honeycomb lattice. Quantities for probing the crossover, double occupancy, spin susceptibility, on-site pair correlation, and kinetic energy are obtained impartially. We find that these quantities indicate the BCS-BEC crossover of the model. This can be interpreted as a competition between Fermionic modes and Bosonic modes which coexist in the single band Hubbard model on a honeycomb lattice with attractive interaction.

–

Authors

  • Shi-Quan Su

    Department of Physics and Institue of Theoretical Physics, The Chinese University of Hong, Hong Kong, China

  • Ka-Ming Tam

    Department of Physics and Astronomy, University of Waterloo, Canada, University of Waterloo

  • Lin Haiqing

    Department of Physics and Institue of Theoretical Physics, The Chinese University of Hong, Hong Kong, China, Department of Physics and Institute of Theoretical Physics, The Chinese University of Hong Kong, Shatin, NT, Hong Kong, China, Department of Physics and ITP, The Chinese University of Hong Kong, Hong Kong, China, Chinese University of Hong Kong, Department of Physics, The Chinese University of Hong Kong, Shatin, N. T., Hong Kong