Unconventional heavy-fermion superconductivity of a new transuranium compound NpPd 5Al 2

Dai Aoki, Yoshinori Haga, Tatsuma D. Matsuda, Naoyuki Tateiwa, Shugo Ikeda, Yoshiya Homma, Hironori Sakai, Yoshinobu Shiokawa, Etsuji Yamamoto, Akio Nakamura, Rikio Settai, Yoshichika Onuki

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114 Citations (Scopus)


We succeeded in growing a new transuranium compound NpPd 5Al 2 with the tetragonal crystal structure by the Pb-flux method, and measured the electrical resistivity, specific heat, magnetic susceptibility and magnetization. NpPd 5Al 2 is found to be a paramagnetic heavy-fermion superconductor with strong coupling ΔC=γT c = 2:33 [T c = 4:9K and γ = 200 mJ/(K 2·mol)]. The upper critical field H c2 at 0K is large and highly anisotropic: H c2(0) = 37 kOe for H ∥ [100] and H c2(0) = 143 kOe for H ∥ [001]. H c2 is found to be strongly suppressed by the magnetic field, and the magnetization curve indicates a step-like increase at H c2, which are due to the paramagnetic effect. The low-temperature electronic specific heat approximately follows the T 3-dependence, indicating the existence of point nodes in the energy gap. The d-wave superconductivity with point nodes is most likely realized in this compound.

Original languageEnglish
Article number063701
Journaljournal of the physical society of japan
Issue number6
Publication statusPublished - 2007 Jun


  • Heavy-fermion superconductivity
  • Non-Fermi liquid
  • NpPd Al
  • Paramagnetic effect

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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