Thermal effects versus spin nematicity in a frustrated spin-1/2 chain

TL;DR

This study uses NMR to investigate the spin-nematic phase in a frustrated spin-1/2 chain, revealing that thermal effects can mimic signatures previously attributed to spin nematicity, thus challenging prior claims.

Contribution

It demonstrates that temperature-dependent NMR shifts can lead to false positives in detecting spin nematic phases, emphasizing the need for careful thermal analysis.

Findings

The observed magnetization reduction is thermally activated.

Thermal effects can mimic spin-nematic signatures in NMR data.

Previous claims of spin nematicity in this compound are likely due to thermal artifacts.

Abstract

The spin-nematic phase is an intriguing state of matter that lacks usual long-range dipolar order, yet it exhibits higher multipolar order. This makes its detection extremely difficult and controversial. Recently, nuclear magnetic resonance (NMR) has been proposed as one of the most suitable techniques to confirm its existence. We report a $^{17}$O NMR observation of the reduction of the local magnetization in the polarized state of the frustrated spin-1/2 chain $\beta$-TeVO$_4$, which was previously proposed to be a fingerprint of the spin-nematic behavior. However, our detailed study shows that the detected missing fraction of the magnetization, probed by NMR frequency shift, is thermally activated, thus undermining the presence of the spin-nematic phase in the investigated compound. This highlights the importance of careful considerations of temperature-dependent NMR shift that has been overlooked in previous studies of spin nematicity.