2008/06/30 by S. Kawasaki, Kengo Katayama, K. Katayama +8
Materials Science · Physics and Astronomy · #Iron-based superconductors research #Physics of Superconductivity and Magnetism #Rare-earth and actinide compounds #cond-mat.str-el #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevb.78.064510
published as Phys. Rev. B 78, 064510 (2008) · 6pages, 9figures
arxiv created 2008/06/30 · openalex publication_date 2008/08/12 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We report 123Sb nuclear-quadrupole-resonance (NQR) measurements of the filled skutterudite heavy-fermion superconductor PrOs4Sb12 under high pressure. The temperature dependence of NQR frequency and the spin-lattice relaxation rate 1/T1 indicate that the crystal-electric-field splitting \ensuremathΔCEF between the ground-state \ensuremathΓ1 singlet and the first-excited-state \ensuremathΓ4(2) triplet decreases with increasing pressure. ac-susceptibility measurements indicate that the superconducting transition temperature (Tc) also decreases with increasing pressure. However, above P\ensuremath∼2 GPa, both \ensuremathΔCEF and Tc do not depend on external pressure up to P=3.82 GPa. These pressure dependences of \ensuremathΔCEF and Tc suggest an intimate relationship between quadrupole excitations associated with the \ensuremathΓ4(2) level and unconventional superconductivity in PrOs4Sb12. In the superconducting state, 1/T1 below Tc=1.55 and 1.57 K at P=1.91 and 2.63 GPa shows a power-law temperature variations and is proportional to T\phantom\rule0.1em0ex5 at temperatures considerably below Tc. These data can be well fitted by the gap model \ensuremathΔ(\ensuremathθ)=\ensuremathΔ0 sin \ensuremathθ, with \ensuremathΔ0=3.08kBTc and 3.04kBTc for P=1.91 and 2.63 GPa, respectively. The results indicate that there exist point nodes in the gap function.