Pairing properties of cold fermions in the honeycomb lattice

TL;DR

This paper investigates the pairing behavior of ultracold fermions in a honeycomb optical lattice, highlighting how the linear dispersion of Dirac fermions influences superfluid properties and critical temperatures.

Contribution

It provides a mean-field analysis of pairing in honeycomb lattices, emphasizing signatures of Dirac fermions and estimating critical temperatures beyond mean-field theory.

Findings

Linear dispersion signatures in local order parameter

Response of the system to external perturbations

Estimated critical temperature for pair condensation

Abstract

The pairing properties of ultracold fermions, with an attractive interaction, loaded in a honeycomb (graphene-like) optical lattice are studied in a mean-field approach. We emphasize, in the presence of a harmonic trap, the unambiguous signatures of the linear dispersion relation of the band structure around half-filling (i.e. the massless Dirac fermions) in the local order parameter, in particular in the situations of either imbalance hoping parameters or imbalance populations. It can also be observed in the system response to external perturbation, for instance by measuring the pair destruction rate when modulating the optical lattice depth. Going beyond the mean-field level, we estimate the critical temperature for the "condensation" of the preformed pairs.