Evolution of superconductor pairing interactions from weak to strong coupling on a honeycomb lattice
Shi-Quan Su, Ka-Ming Tam, Hai-Qing Lin
We study the evolution of the pairing from weak to strong coupling on a honeycomb lattice by quantum Monte Carlo. We show numerical evidence of the BCS-Bose-Einstein condensation (BEC) crossover as the coupling strength increases on a honeycomb lattice with small Fermi surface by measuring a wide range of observables: double occupancy, spin susceptibility, local pair correlation, and kinetic energy. Although at low energy, the model sustains Dirac fermions, we do not find significant qualitative difference in the BCS-BEC crossover as compared to those with an extended Fermi surface, except at weak-coupling, BCS regime.
arXiv:0902.3242•Physical Review B•Sep 29, 2009•7 citations