Scalar spin chirality and quantum Hall effect on a triangular lattice

TL;DR

This paper demonstrates that on a triangular lattice at 3/4 filling, a non-coplanar chiral spin order naturally emerges, leading to a spontaneous quantum Hall effect due to perfect Fermi surface nesting.

Contribution

It reveals the emergence of scalar spin chirality and quantum Hall effect in Kondo and Hubbard models on a triangular lattice at specific filling.

Findings

Chiral spin order arises from perfect Fermi surface nesting.

The chiral phase exhibits a quantized Hall conductivity of e^2/h.

Triple-Q magnetic ordering is analogous to Neel order on square lattices.

Abstract

We study the Kondo Lattice and Hubbard models on a triangular lattice for band filling factor 3/4. We show that a simple non-coplanar chiral spin ordering (scalar spin chirality) is naturally realized in both models due to perfect nesting of the Fermi surface. The resulting triple-Q magnetic ordering is a natural counterpart of the collinear Neel ordering of the half-filled square lattice Hubbard model. We show that the obtained chiral phase exhibits a spontaneous quantum Hall-effect with sigma_{xy}= e^2/h.