Realization of an antiferromagnetic superatomic graphene: Dirac Mott insulator and circular dichroism Hall effect

Based on first-principles calculations, we investigate the electronic and topological properties of an antiferromagnetic (AFM) superatomic graphene lattice superimposed on a bipartite honeycomb lattice governed by Lieb’s theorem of itinerant magnetism. It affords a concrete material realization of the AFM honeycomb model with a Dirac Mott insulating state, characterized by a gap opening at the Dirac point due to inversion symmetry breaking by long-range AFM order. The opposite Berry curvatures of the K and K′ valleys induces a circular dichroism (CD) Hall effect. Different from the valley Hall effect that activates only one valley, the CD Hall effect activates carriers from both K and K′ valleys, generating the opposite spin carriers and opposite directions of transversal Hall currents for the left- and right-handed circularly polarized light, respectively.