Symmetry Reduction in the Quantum Kagome Antiferromagnet Herbertsmithite

TL;DR

This study uses magnetometry and electron spin resonance to investigate herbertsmithite, revealing defect behaviors and potential structural distortions that influence its quantum spin-liquid state.

Contribution

It provides new experimental insights into defect contributions and structural symmetry breaking in herbertsmithite, a key quantum kagome antiferromagnet.

Findings

Identification of two types of magnetic defects

Detection of symmetry-breaking structural distortion

Implications for the spin-liquid ground state

Abstract

Employing complementary torque magnetometry and electron spin resonance on single crystals of herbertsmithite, the closest realization to date of a quantum kagome antiferromagnet featuring a spin-liquid ground state, we provide novel insight into different contributions to its magnetism. At low temperatures, two distinct types of defects with different magnetic couplings to the kagome spins are found. Surprisingly, their magnetic response contradicts the three-fold symmetry of the ideal kagome lattice, suggesting the presence of a global structural distortion that may be related to the establishment of the spin-liquid ground state.