Ground state and excitation properties of the quantum kagom\'{e} system ZnCu$_{3}$(OH)$_{6}$Cl$_{2}$ investigated by local probes

TL;DR

This study investigates the quantum kagome system ZnCu$_{3}$(OH)$_{6}$Cl$_{2}$, revealing a gapless spin liquid state with no long-range order or spin freezing down to very low temperatures, using various local magnetic probes.

Contribution

It provides detailed experimental evidence for a gapless quantum spin liquid state in ZnCu$_{3}$(OH)$_{6}$Cl$_{2}$ through multiple local measurement techniques.

Findings

No sign of long-range magnetic order or spin freezing down to 60 mK.

The density of states follows an $E^{1/4}$ dependence with negligible excitation gap.

Absence of spin-Peierls transition in the studied temperature range.

Abstract

We characterize the ground state and excitation spectrum of the $S=1/2$, nominally pure and perfect kagom\'{e} system ZnCu$_{3}$(OH)$_{6}$Cl$_{2}$ using the following measurements: magnetization, muon spin rotation frequency shift $K$, transverse relaxation time $T_{2}^{\ast}$, and zero field relaxation, and Cl nuclear spin-lattice relaxation $T_{1}$. We found no sign of singlet formation, no long range order or spin freezing, and no sign of spin-Peierls transition even at temperatures as low as 60 mK. The density of states has $E^{1/4}$ energy dependence with a negligible gap to excitation.