Quantum phase transition induced by Dzyaloshinskii-Moriya in the kagome antiferromagnet

TL;DR

This paper demonstrates that increasing Dzyaloshinskii-Moriya interactions in the S=1/2 kagome antiferromagnet induces a quantum phase transition from a disordered to an ordered magnetic phase, with implications for related materials.

Contribution

It identifies the critical Dzyaloshinskii-Moriya coupling value and characterizes the quantum phase transition in the kagome antiferromagnet using exact diagonalizations.

Findings

Quantum phase transition at D_c ≈ 0.1J

Disordered phase for D < D_c

Ordered antiferromagnetic phase for D > D_c

Abstract

We argue that the S=1/2 kagome antiferromagnet undergoes a quantum phase transition when the Dzyaloshinskii-Moriya coupling is increased. For $D<D_c$ the system is in a moment-free phase and for $D>D_c$ the system develops antiferromagnetic long-range order. The quantum critical point is found to be $D_c \simeq 0.1J$ using exact diagonalizations and finite-size scaling. This suggests that the kagome compound ZnCu$_3(OH)$_6$Cl$_3$ may be in a quantum critical region controlled by this fixed point.