Evidence for point nodes in the superconducting gap function in the filled skutterudite heavy-fermion compound PrOs4Sb12: 123Sb-NQR study under pressure

Kouta Katayama, Shinji Kawasaki, Masahide Nishiyama, Hitoshi Sugawara, Daisuke Kikuchi, Hideyuki Sato, Guo-Qing Zheng

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We report 123Sb nuclear quadrupole resonance (NQR) measurements of the filled skutterudite heavyfermion superconductor PrOs4Sb 12 under high pressures of 1.91 and 2.34 GPa. The temperature dependence of NQR frequency and the spin-lattice relaxation rate 1/T1 indicate that the crystal-electric-field splitting ΔCEF between the ground state Γ1 singlet and the first excited state Γ4(2) triplet decreases with increasing pressure. The 1/T1 below Tc = 1.55 K at P = 1:91 GPa shows a power-law temperature variation and is proportional to T5 at temperatures considerably below Tc, which indicates the existence of point nodes in the superconducting gap function. The data can be well fitted by the gap model Δ(θ) = Δ0 sinθ with Δ0 = 3.08kBTc. The relation between the superconductivity and the quadrupole fluctuations associated with the Γ4(2) state is discussed.

Original languageEnglish
Article number023701
JournalJournal of the Physical Society of Japan
Issue number2
Publication statusPublished - Feb 2007



  • NQR
  • Pressure
  • PrOsSb
  • Superconductivity

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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