Gapless spin liquid in the kagome Heisenberg antiferromagnet with Dzyaloshinskii-Moriya interactions

TL;DR

This study uses tensor-network methods to show that a small Dzyaloshinskii-Moriya interaction can destabilize the gapless spin liquid in the kagome Heisenberg antiferromagnet, challenging previous interpretations of experimental data.

Contribution

It provides a quantitative estimate of the critical Dzyaloshinskii-Moriya interaction strength needed to destabilize the gapless spin liquid state.

Findings

Critical Dzyaloshinskii-Moriya strength is approximately 0.012J.

Weak DM interactions can destabilize the gapless spin liquid.

Reassessment of spin-liquid behavior in herbertsmithite is needed.

Abstract

A preponderance of evidence suggests that the ground state of the nearest-neighbor $S = 1/2$ antiferromagnetic Heisenberg model on the kagome lattice is a gapless spin liquid. Many candidate materials for the realization of this model possess in addition a Dzyaloshinskii-Moriya (DM) interaction. We study this system by tensor-network methods and deduce that a weak but finite DM interaction is required to destabilize the gapless spin-liquid state. The critical magnitude, $D_c/J \simeq 0.012(2)$, lies well below the DM strength proposed in the kagome material herbertsmithite, indicating a need to reassess the apparent spin-liquid behavior reported in this system.