Kondo-induced hybrid topological insulator in two-dimensional electron system with a quadratic band crossing point

Abstract

We investigate the Kondo effect in the two-dimensional electron system with a non-trivial quadratic energy band crossing point. We show that the Kondo effect can induce a new hybrid topological insulator phase which is a coexistence state of the quantum anomalous Hall effect and the TRSbroken quantum spin Hall effect. This hybrid topological insulator exhibits not only a quantized charge Hall current but also a net spin current, which are localized at the edge boundaries. This peculiar topological state arises due to the interplay of two marginally relevant operators, i.e., the Kondo-coupling between the electrons and the local magnetic moment and the electron-electron interaction in the two-dimensional system.