Antiferromagnetic Chern insulator in centrosymmetric systems

An antiferromagnetic Chern insulator (AFCI) can exist if the effect of the time-reversal transformation on the electronic state cannot be compensated by a space-group operation. The AFCI state with collinear magnetic order is already realized in noncentrosymmetric honeycomb structures through the Kane-Mele-Hubbard model. In this paper, we demonstrate the existence of the collinear AFCI in a square-lattice model which preserves the inversion symmetry. Our study relies on the time-reversal-invariant Harper-Hofstadter-Hubbard model extended by a next-nearest-neighbor hopping term including spin-orbit coupling and a checkerboard potential. We show that an easy z-axis AFCI appears between the band insulator at weak and the easy xy-plane AF Mott insulator at strong Hubbard repulsion provided the checkerboard potential is large enough. The close similarity between our results and the results obtained for the noncentrosymmetric Kane-Mele-Hubbard model suggests the AFCI as a generic consequence of spin-orbit coupling and strong electronic correlation which exists beyond a specific model or lattice structure. An AFCI with the electronic and the magnetic properties originating from the same strongly interacting electrons is a promising candidate for a strong magnetic blueshift of the charge gap below the Neel temperature and for realizing the quantum anomalous Hall effect at higher temperatures so that applications for data processing become possible.

Automated summary

In this paper, the existence of an antiferromagnetic Chern insulator (AFCI) in a square-lattice model is demonstrated. The study shows that the AFCI can be formed due to the spin-orbit coupling and strong electronic correlation, which suggests the generic consequence of these factors beyond a specific model or lattice structure. The AFCI has potential applications for a strong magnetic blueshift of the charge gap below the Neel temperature and for realizing the quantum anomalous Hall effect at higher temperatures.