Quantum magnetism in the paratacamite family: towards an ideal kagome lattice

TL;DR

This study investigates the magnetic properties of the paratacamite family, revealing a lack of magnetic freezing in the x=1 compound down to very low temperatures, challenging theoretical expectations for kagome antiferromagnets.

Contribution

It provides experimental MuSR evidence on the magnetic ground states across the paratacamite family, highlighting the absence of freezing in the x=1 compound and identifying a transition around x=0.5.

Findings

No magnetic freezing in x=1 down to 50 mK

Transition from dynamical to frozen state around x=0.5

Relevance of a singlet state in the x=1 compound

Abstract

We report MuSR measurements on the S=1/2 (Cu2+) paratacamite Zn_xCu_{4-x}(OH)_6Cl_2 family. Despite a Weiss temperature of -300 K, the x=1 compound is found to have no transition to a magnetic frozen state down to 50 mK as theoretically expected for the kagome Heisenberg antiferromagnet. We find that the limit between a dynamical and a frozen inhomogeneous ground state occurs around x=0.5. For x=1, we discuss the relevance to a singlet picture.