Three-component fermionic atoms with repulsive interaction in optical lattices

We investigate three-component (colors) repulsive fermionic atoms in optical lattices using the dynamical mean-field theory. Depending on the anisotropy of the repulsive interactions, either a color density-wave state or a color-selective staggered state appears at half filling. In the former state, pairs of atoms with two of the three colors and atoms with the third color occupy different sites alternately. In the latter state, atoms with two of the three colors occupy different sites alternately and atoms with the third color are itinerant throughout the system. When the interactions are isotropic, both states are degenerate. We discuss the results using an effective model.

Figure 1

(a) Quasiparticle weight $Z_{\alpha }$ and (b) difference between atom numbers of sublattices with color $\alpha$ per site, $M_{\alpha }$, for $U^{\text{'}\text{'}}/U=2$ and $U^{\text{'}}/U=0.6$ as functions of $U/t$.

Figure 2

Difference between atom numbers of sublattices with color $\alpha$ per site, $M_{\alpha }$, for $U^{\text{'}\text{'}}/U=2$ and $U/t=3$ as functions of $U^{\text{'}}/U$.

Figure 3

Single-particle excitation spectra for (a) $U^{\text{'}}/U=0.6$ and (b) $U^{\text{'}}/U=1.8$ by fixing $U^{\text{'}\text{'}}/U=2$ and $U/t=3$.

Figure 4

(a) Energies and (b) quasiparticle weights for $U^{\text{'}\text{'}}/U=2$ and $U^{\text{'}}/U=0.6$ as functions of $U/t$. (a) The thick (red) line represents the energy of the color DW state, while the thin (blue) line represents the energy obtained by the two-site DMFT without dividing the bipartite lattice into the sublattices.

Figure 5

(a) Order parameters and (b) energies for $U^{\text{'}\text{'}}=U^{\text{'}}$ and $U/t=5$ as functions of $U^{\text{'}}/U$.