The Herbertsmithite Hamiltonian: $\mu$SR measurements on single crystals

TL;DR

This study uses muon spin rotation to investigate the magnetic properties of Herbertsmithite, revealing anisotropic interactions and directional dependence in spin polarization, advancing understanding of kagome antiferromagnets.

Contribution

It provides experimental evidence of anisotropic axial interactions in Herbertsmithite, challenging previous models based solely on Dzyaloshinskii-Moriya interactions.

Findings

Spins are more easily polarized perpendicular to the kagome plane.

Magnetization differences cannot be explained by Dzyaloshinskii-Moriya interactions alone.

Presence of anisotropic axial interactions in the material.

Abstract

We present transverse field muon spin rotation/relaxation measurements on single crystals of the spin-1/2 kagome antiferromagnet Herbertsmithite. We find that the spins are more easily polarized when the field is perpendicular to the kagome plane. We demonstrate that the difference in magnetization between the different directions cannot be accounted for by Dzyaloshinksii-Moriya type interactions alone, and that anisotropic axial interaction is present.