Controlled pairing symmetry of the superfluid state in systems of three-component repulsive fermionic atoms in optical lattices

Abstract

We investigate the pairing symmetry of the superfluid state in repulsively interacting threecomponent (color) fermionic atoms in optical lattices. When two of the three color-dependent repulsions are much stronger than the other, pairing symmetry is an extended s wave, although the superfluid state appears adjacent to the paired Mott insulator in the phase diagram. On the other hand, when two of the three color-dependent repulsions are weaker than the other, pairing symmetry is a d x 2 −y 2 -wave. This change in pairing symmetry is attributed to the change in the dominant quantum fluctuations from the density fluctuations of unpaired atoms and the color-density wave fluctuations to the color-selective antiferromagnet fluctuations. This phenomenon can be studied using existing experimental techniques.

Mott Transitions and Staggered Orders in the Three-Component Fermionic System: Variational Cluster Approach

“…[17][18][19] Moreover, the DMFT calculations assuming translational symmetry breaking have shown that two types of staggered orders appear, depending on the anisotropy in * ohta@faculty.chiba-u.jp the interaction strengths, and the first-order phase transition occurs between the two at the SU(3) symmetric point. [19][20][21][22] Superfluidity has also been reported to occur, even in the repulsive Hubbard model near half filling, when the interaction strengths are anisotropic, suggesting the presence of an exotic pairing mechanism, 19,[23][24][25] where the fluctuations of the staggered orders may cause the pairing. We may therefore point out that the effects of the lattice geometry and Fermi surface nesting, which are important in the formation of the staggered orders, should be examined carefully in the low-dimensional systems.…”