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

We investigate the Kondo effect in a two-dimensional electron system with a nontrivial quadratic energy band crossing point. We show that the Kondo effect can induce a hybrid topological insulator phase, which is a coexistence state of the quantum anomalous Hall effect and the time-reversal-symmetry-broken 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. [ABSTRACT FROM AUTHOR]