Emergent chiral spin ordering and anomalous Hall effect in a kagome lattice at a 1/3 filling

Abstract

The study of electronic and magnetic properties of a kagome lattice has been an active research area searching for topological phases of matters. In particular, the kagome system with transition metal stannides exhibit interesting anomalous Hall effects driven by ferromagnetic or noncollinear magnetic ordering. In this paper, motivated by these pioneer works, we study strongly correlated spin-orbit coupled electrons in a kagome lattice at a 1/3 filling. Using both the Hartree-Fock approach and effective model analysis, we report quantum phase transitions accompanied by the distinct charge and magnetic ordered phases. Especially, for strongly interacting limit, we discover new types of 1(2)-pinned metallic states, which are understood by effective localized electron models. Furthermore, when the spin-orbit coupling is present, it turns out that such pinned metallic states open a wide region of the Chern insulating phase with chiral spin ordering. Thus the quantum anomalous Hall effect is expected with the emergent scalar spin chirality. Our theory provides a theoretical platform of strongly interacting kagome metal which is applicable to transition metal stannides.