Controlled superfluid pairing symmetry of repulsively interacting three-component fermionic atoms in optical lattices

We investigate the pairing symmetry of the superfluid state in repulsively interacting three-component (colors) fermionic atoms in optical lattices. When two of the three color-dependent repulsions are much larger 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 [1]. As the difference between the three repulsions is decreased in square optical lattices, the extended s-wave pairing changes into a nodal s-wave pairing, a d$_{xy}$-wave pairing, and then into a d$_{x2-y2}$-wave pairing. This change in pairing symmetry is attributed to the competition among the density fluctuations of unpaired atoms, the quantum fluctuations of the color-density wave, and those of the color-selective antiferromagnet [2]. This phenomenon can be studied in $^{6}$Li atoms and $^{171}$Yb-$^{173}$Yb mixtures in optical lattices using existing experimental techniques.\\[4pt] [1] K. Inaba and S. Suga, \textit{Phys. Rev. Lett.} \textbf{108} (2012) 255301.\\[0pt] [2] K. Inaba and S. Suga, arXiv:1408.6582.