Mean field study of the topological Haldane-Hubbard model of spin-$1/2$ fermions

Abstract: Motivated by exploring the effect of interactions on Chern insulators, and by recent experiments realizing topological bands for ultracold atoms in synthetic gauge fields, we study the honeycomb lattice Haldane-Hubbard model of spin-$1/2$ fermions. Using an unrestricted mean field approach, we map out the instability of the topological band insulator towards magnetically ordered insulators which emerge with increasing Hubbard repulsion. In addition to the topological N\'eel phase, we recover various chiral noncoplanar magnetic orders previously identified within a strong coupling approach. We compute the band structure of these ordered phases, showing that the triple-$Q$ tetrahedral phase harbors topological Chern bands with large Chern numbers.