Perturbation on Hyperfine-enhanced $^{141}$Pr Nuclear Spin Dynamics Associated with Antiferroquadrupolar Order in PrV$_2$Al$_{20}$

TL;DR

This study investigates the hyperfine-enhanced $^{141}$Pr nuclear spin dynamics in PrV$_2$Al$_{20}$, revealing no time-reversal symmetry breaking but showing perturbations linked to antiferroquadrupolar order through muon spin relaxation measurements.

Contribution

It provides new insights into the nuclear spin behavior and multipolar order in PrV$_2$Al$_{20}$ using muon spin relaxation, highlighting the effects of AFQ correlations.

Findings

No explicit time-reversal symmetry breaking detected.

Observation of hyperfine-enhanced $^{141}$Pr nuclear spin fluctuations.

Increase in muon spin-lattice relaxation rate below 1 K.

Abstract

The nature of multipolar order and hyperfine-enhanced (HE) $^{141}$Pr nuclear spin dynamics in PrV$_2$Al$_{20}$ was investigated using the muon spin relaxation technique. No explicit sign of time-reversal symmetry breaking was found below the multipolar order temperature $T_Q\sim 0.6$ K in a zero applied field as anticipated on the basis of the antiferroquadrupolar (AFQ) order picture proposed by Sakai and Nakatsuji [J. Phys. Soc. Jpn. 80, 063701 (2011)]. Further evidence of the nonmagnetic ground state was obtained from the observation of HE $^{141}$Pr nuclear spin fluctuations in the MHz scale. A marked increase in the muon spin-lattice relaxation rate (1/$T_{\rm 1,\mu}$) was observed below 1 K with decreasing temperature, which was attributed to the perturbation on the HE $^{141}$Pr nuclear spin dynamics associated with the development of AFQ correlations. The longitudinal field dependence of 1/$T_{\rm 1,\mu}$ revealed that the enhanced $^{141}$Pr nuclear spin accidentally has an effective gyromagnetic ratio close to that of the muon.