Exact Chiral Spin Liquid with Stable Spin Fermi Surface on the Kagome Lattice

TL;DR

This paper introduces an exactly solvable Kitaev-type quantum spin model on the kagome lattice, revealing a stable spin Fermi surface and a topological chiral spin liquid with gapless edge states, expanding understanding of quantum spin liquids.

Contribution

It presents a new exactly solvable model with a stable spin Fermi surface and a topological chiral spin liquid phase on the kagome lattice.

Findings

Identifies a topological gapped chiral spin liquid with edge states.

Discovers a gapless chiral spin liquid phase with a stable spin Fermi surface.

Shows the spin Fermi surface's stability against weak perturbations.

Abstract

We study an exactly solvable quantum spin model of Kitaev type on the kagome lattice. We find a rich phase diagram which includes a topological (gapped) chiral spin liquid with gapless chiral edge states, and a gapless chiral spin liquid phase with a spin Fermi surface. The ground state of the current model contains an odd number of electrons per unit cell which qualitatively distinguishes it from previously studied exactly solvable models with a spin Fermi surface. Moreover, we show that the spin Fermi surface is stable against weak perturbations.