Perturbation on hyperfine-enhanced ~(141)Pr nuclear spin dynamics associated with antiferroquadrupolar order in PrV_2Al_(20)

摘要

The nature of multipolar order and hyperfine-enhanced (HE) ~(141)Pr nuclear spin dynamics in PrV_2Al_(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 ～ 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_(1,μ)) 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_(1,μ) revealed that the enhanced ~(141)Pr nuclear spin accidentally has an effective gyromagnetic ratio close to that of the muon.