123Sb-NQR study of unconventional superconductivity in the filled skutterudite heavy-fermion compound PrOs4Sb12 under high pressure up to P = 3.82 GPa

Abstract

We report ${}^{123}$Sb nuclear quadrupole resonance (NQR) measurements of the filled skutterudite heavy-fermion superconductor PrOs${}_4$Sb${}_{12}$ under high pressure. The temperature dependence of NQR frequency and the spin-lattice relaxation rate $1/T_1$ indicate that the crystal-electric-field splitting ${\Delta }_{\mathrm{CEF}}$ between the ground state ${\Gamma }_1$ singlet and the first excited state ${\Gamma }_4^{(2)}$ triplet decreases with increasing pressure. Ac-susceptibility measurements indicate that the superconducting transition temperature ($T_{\mathrm{c}}$) also decreases with increasing pressure. However, above $P$ $\sim$ 2 GPa, both ${\Delta }_{\mathrm{CEF}}$ and $T_{\mathrm{c}}$ do not depend on external pressure up to $P$ = 3.82 GPa. These pressure dependences of ${\Delta }_{\mathrm{CEF}}$ and $T_{\mathrm{c}}$ suggest an intimate relationship between quadrupole excitations associated with the ${\Gamma }_4^{(2)}$ level and unconventional superconductivity in PrOs${}_4$Sb${}_{12}$. In the superconducting state, 1/$T_1$ below $T_{\mathrm{c}}$ = 1.55 and 1.57 K at $P$ = 1.91 and 2.63 GPa shows a power-law temperature variations and are proportional to $T^5$ at temperatures considerably below $T_{\mathrm{c}}$. These data can be well fitted by the gap model $\Delta (\theta )={\Delta }_0\sin \theta$ with ${\Delta }_0$ = 3.08 $k_{\mathrm{B}}{T}_{\mathrm{c}}$ and 3.04 $k_{\mathrm{B}}{T}_{\mathrm{c}}$ for $P$ = 1.91 and 2.63 GPa, respectively. The results indicate there exists point nodes in the gap function.

arXiv comment6pages, 9figures

References in corpus (28)

• Time-Reversal Symmetry-Breaking Superconductivity in Heavy Fermion PrOs4Sb12 detected by Muon Spin Relaxation
• Multiple Superconducting Phases in New Heavy Fermion Superconductor PrOs4Sb12
• 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}
• Evidence for Unconventional Strong-coupling Superconductivity in PrOs_4Sb_12 : An Sb Nuclear Quadrupole Resonance (NQR) Study
• Low temperature specific heat of the heavy fermion superconductor PrOs${}_4$Sb${}_{12}$
• Fermi surface of the heavy fermion superconductor PrOs${}_4$Sb${}_{12}$
• The Crystal Field Potential of PrOs4Sb12: Consequences for Superconductivity
• Multiband superconductivity in the heavy fermion compound PrOs4Sb12
• Probing the superconducting gap symmetry of PrOs${}_4$Sb${}_{12}$: A penetration depth study
• muSR linewidth and isotropic pairing in superconducting PrOs4Sb12
• Direct Observation of Quadrupolar Excitons in the Heavy-Fermion Superconductor PrOs${}_4$Sb${}_{12}$
• Field Dependence of Electronic Specific Heat in Two-Band Superconductors
• Superconducting phase diagram of the filled skuterrudite PrOs4Sb12
• Very Low Temperature Tunnelling Spectroscopy in the heavy fermion superconductor PrOs${}_4$Sb${}_{12}$
• Sb-NQR probe for superconducting property in the Pr-based filled skutterudite compound PrRu4Sb12
• Multiband Superconductivity in Filled-Skutterudite Compounds (Pr_{1-x}La_{x})Os_{4}Sb_{12}: An Sb Nuclear-Quadruple-Resonance (NQR) Study
• A phenomenology for multiple phases in the heavy fermion skutterudite superconductor PrOs4Sb12
• A theory of new type of heavy-electron superconductivity in PrOs_4Sb_12: quadrupolar-fluctuation mediated odd-parity pairings
• Evolution of crystalline electric field effects, superconductivity, and heavy fermion behavior in the specific heat of Pr(Os${}_{1-x}$Ru${}_x$)${}_4$Sb${}_{12}$
• On Superconducting Double Transition in PrOs_4_Sb_12
• Multiphase Superconductivity in Skutterudite PrOs_4Sb_12
• Triplet superconductivity in the skutterudite PrOs_4Sb_12
• Eliashberg theory of superconductivity and inelastic rare-earth impurity scattering in filled skutterudite La${}_{1-x}$Pr${}_x$Os${}_4$Sb${}_{12}$
• Sb-NQR probe for multipole degree of freedom in the first Pr-based heavy-fermion superconductor PrOs${}_4$Sb${}_{12}$
• Symmetry properties of the nodal superconductor PrOs4Sb12
• Exciton Mediated Triplet Superconductivity in Th System PrOs4Sb12
• Impurity induced density of states and residual transport in nonunitary superconductors

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