Novel magnetic orderings in the kagome Kondo-lattice model

TL;DR

This paper investigates how weak-coupling instabilities in the kagome Kondo-lattice model at specific band fillings lead to exotic magnetic orders, including states with spontaneous quantum anomalous Hall effects.

Contribution

It combines analytical and numerical methods to reveal new magnetic orderings and their connection to topological quantum anomalous Hall states in the kagome Kondo-lattice model.

Findings

Identification of magnetic orderings at singular Fermi surface points

Discovery of magnetic states that exhibit quantum anomalous Hall effect

Demonstration of weak-coupling instabilities leading to topologically nontrivial phases

Abstract

We consider the Kondo-lattice model on the kagome lattice and study its weak-coupling instabilities at band filling fractions for which the Fermi surface has singularities. These singularites include Dirac points, quadratic Fermi points in contact with a flat band, and Van Hove saddle points. By combining a controlled analytical approach with large-scale numerical simulations, we demonstrate that the weak-coupling instabilities of the Kondo-lattice model lead to exotic magnetic orderings. In particular, some of these magnetic orderings produce a spontaneous quantum anomalous Hall state.