Topological Properties of Magnetically Ordered Heavy-Fermion Systems in the Presence of Mirror Symmetry

We explore topological states with magnetic order in heavy-fermion systems by taking account of a mirror symmetry. Although in the absence of spatial symmetry, there is no topological phase in the two-dimensional (2D) antiferro-magnetic phases at half filling, we demonstrate that a topological phase emerges in the presence of mirror symmetry. This is explicitly shown for a 2D periodic Anderson model. Furthermore, around quarter filling, our analysis shows that a half-metallic state emerges in the ferromagnetic phase, where a spin-selective gap opens, resulting in nontrivial properties characterized by a Chern number. In contrast to the previously proposed models, our scenario can even apply for spin-nonconserving systems in the presence of spin-orbit coupling.