Attractive Hubbard Model on a Honeycomb Lattice
Abstract
We study the attractive fermionic Hubbard model on a honeycomb lattice using determinantal quantum Monte Carlo simulations. By increasing the interaction strength U (relative to the hopping parameter t) at half-filling and zero temperature, the system undergoes a quantum phase transition at 5.0 < U_c/t < 5.1 from a semi-metal to a phase displaying simultaneously superfluid behavior and density order. Doping away from half-filling, and increasing the interaction strength at finite but low temperature T, the system always appears to be a superfluid exhibiting a crossover between a BCS and a molecular regime. These different regimes are analyzed by studying the spectral function. The formation of pairs and the emergence of phase coherence throughout the sample are studied as U is increased and T is lowered.
Keywords
Cite
@article{arxiv.0909.2987,
title = {Attractive Hubbard Model on a Honeycomb Lattice},
author = {K. L. Lee and K. Bouadim and G. G. Batrouni and F. Hebert and R. T. Scalettar and C. Miniatura and B. Gremaud},
journal= {arXiv preprint arXiv:0909.2987},
year = {2009}
}