Sb-NQR probe for multipole degree of freedom in the first Pr-based heavy-fermion superconductor PrOs${}_4$Sb${}_{12}$

Abstract

We report ${}^{121,123}$Sb nuclear quadrupole resonance (NQR) measurements in the filled-skutterudite superconductor PrOs${}_4$Sb${}_{12}$ in the temperature range of 0.05-30 K. The electric field gradients (EFG), $V_{zz}$ and $V_{xx}-V_{yy}$, at the Sb site exhibit unusual temperature dependence below 30 K. To explain these features, we discuss the coupling between the Sb nuclear quadrupole moment and Pr $4f^2$-derived multipole moments. The observed $T$ dependence of EFG is well explained by the CEF quasi-quartet consisted of ${\Gamma }_1$ singlet and ${\Gamma }_4^{(2)}$ triplet states in the cubic point group $T_h$. These results, in turn, are indicative of the importance of the coupling between the ${}^{121,123}$Sb quadrupole moments and the hexadecapole moment caused by the quasi-quartet.

7 pages, 4 figures, (jpsj2.cls). to be published in J. Phys. Soc. Jpn. Vol.74, No.10

References in corpus (8)

• Thermodynamical Study on the Heavy-Fermion Superconductor PrOs4Sb12: Evidence for Field-Induced Phase Transition
• Quadrupolar effect and rattling motion in heavy fermion superconductor PrOs_4Sb_{12}
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• Fermi surface of the heavy fermion superconductor PrOs${}_4$Sb${}_{12}$
• The Crystal Field Potential of PrOs4Sb12: Consequences for Superconductivity
• Theory of Crystalline Electric Field and Kondo Effect in Pr Skutterudites
• Invariant Form of Hyperfine Interaction with Multipolar Moments - Observation of Octupolar Moments in NpO${}_2$ and CeB${}_6$ by NMR -
• Exciton Mediated Superconductivity in PrOs4Sb12

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