Dirac and Chiral Quantum Spin Liquids on the Honeycomb Lattice in a Magnetic Field

TL;DR

This paper investigates the effects of magnetic fields on the $K$-$ extGamma$ model in honeycomb lattice materials, revealing field-dependent quantum spin liquid phases including Dirac and chiral states, consistent with recent experiments.

Contribution

It introduces a slave-particle and Variational Monte Carlo approach to identify and characterize field-induced quantum spin liquids on the honeycomb lattice, including Dirac and chiral phases.

Findings

Identification of a gapless Dirac spin liquid for certain in-plane fields.

Prediction of a Kalmeyer-Laughlin-type chiral spin liquid with quantized thermal Hall effect.

Reproduction of the magnetic order to disordered phase transition observed experimentally.

Abstract

Motivated by recent experimental observations in $\alpha$-RuCl$_3$, we study the $K$-$\Gamma$ model on the honeycomb lattice in an external magnetic field. By a slave-particle representation and Variational Monte Carlo calculations, we reproduce the phase transition from zigzag magnetic order to a field-induced disordered phase. The nature of this state depends crucially on the field orientation. For particular field directions in the honeycomb plane, we find a gapless Dirac spin liquid, in agreement with recent experiments on $\alpha$-RuCl$_3$. For a range of out-of-plane fields, we predict the existence of a Kalmeyer-Laughlin-type chiral spin liquid, which would show an integer-quantized thermal Hall effect.