Spin chirality ordering and anomalous Hall effect in the ferromagnetic Kondo lattice model on the triangular lattice

TL;DR

This paper explores the ground-state phases of the ferromagnetic Kondo lattice model on a triangular lattice, revealing a noncoplanar spin order with scalar chirality at specific fillings, which influences the anomalous Hall effect and topological properties.

Contribution

It identifies a stable noncoplanar four-sublattice spin order with scalar chirality at 1/4 filling, expanding understanding of magnetic and topological phases in the model.

Findings

Discovery of a noncoplanar four-sublattice order with scalar chirality at 1/4 filling.

Identification of a wide parameter range where the 1/4-filling phase is stable.

Calculation of Hall conductivity showing anomalous Hall effect in chiral-ordered phases.

Abstract

We investigate the ground-state phase diagram for the ferromagnetic Kondo lattice model on a triangular lattice by a variational calculation for various spin orderings up to a four-site unit cell. We find that a noncoplanar four-sublattice ordering with a finite scalar spin chirality emerges at and around 1/4 filling, in addition to the 3/4-filled case, which was predicted to be induced by the perfect nesting of the Fermi surface [I. Martin and C. D. Batista: Phys. Rev. Lett. {\bf 101} (2008) 156402]. The 1/4-filling phase is stable in a wider range of parameters than the 3/4-filling one, and includes a large region of gapped insulating state characterized by a Chern number. We also compute the Hall conductivity in the chiral-ordered phases.