Topological properties of mirror symmetric Kondo half-metals

The concept of topology in condensed matter physics has been widely recognized since the theoretical discovery of topological insulators by Kane and Mele. Recently, the electron correlation effects on topological properties have attracted much attention because of nontrivial features that do not emerge in weakly correlated electron systems, such as topological Kondo insulators, magnetic orders in topological insulators, etc.
In the previous study, it has been elucidated that in the presence of spin U(1) symmetry, even ferromagnetic (FM) systems can acquire topological properties; system with spin U(1) symmetry can have a spin-selective gap which results in nontrivial topological properties. In general, however, spin U(1) symmetry is considered to be broken in heavy-fermion systems because of their strong spin-orbit coupling (SOC). This fact motivates us to ask whether the above topological phases can be realized in the presence of SOC.
In this study, we demonstrate that even in the absence of spin U(1) symmetry, ferromagnetic phases with mirror symmetry can have the topological properties. In particular, we analyze an effective model describing a thin film of SmB₆, and find the topological state in a half-metallic FM phase characterized by a mirror Chern number.