Magnetic and electrical properties of NpTGa5 (T = Fe, Rh and Ni)

Dai Aoki, Yoshiya Homma, Yoshinobu Shiokawa, Hironori Sakai, Etsuji Yamamoto, Akio Nakamura, Yoshinori Haga, Rikio Settai, Yoshichika Onuki

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53 Citations (Scopus)


We grew high-quality single crystals of NpTGa5 (T = Fe, Rh, and Ni) with a tetragonal structure by the Ga-flux method and measured their electrical resistivity, specific heat, magnetic susceptibility, and magnetization. All the investigated compounds undergo magnetic ordering. NpFeGa5 orders antiferromagnetically at TN = 118K and shows another magnetic transition at T* = 78 K. A relatively large electrical resistivity indicates that NpFeGa5 might be a low-carrier compound. NpRhGa5 also orders antiferromagnetically at TN1 = 36 K. Below another magnetic transition at TN2 = 32 K, the antiferromagnetic easy-axis is most likely changed from [001] to the (001) plane. On the other hand, NpNiGa5 undergoes ferromagnetic ordering at TC = 30 K, where the magnetic moment of Np is directed along the [001] direction. Furthermore, below another magnetic transition at T* = 18 K, the ordered moment is discontinuously enlarged and a change of the magnetic structure occurs. The electronic specific heat coefficients are approximately determined as 30, 52, and 100 mJ/K2·mol for NpFeGa 5, NpRhGa5, and NpNiGa5, respectively. The magnetic susceptibility approximately follows the Curie-Weiss law at high temperatures (250 < T < 300 K) with effective magnetic moments ranging from 2.4 to 2.6μB/Np for NpRhGa5 and NpNiGa 5, indicating that the localized 5f4 electronic states are most likely applicable to these compounds at high temperatures.

Original languageEnglish
Pages (from-to)2323-2331
Number of pages9
JournalJournal of the Physical Society of Japan
Issue number8
Publication statusPublished - 2005 Aug


  • Electrical resistivity
  • Magnetic susceptibility
  • Magnetization
  • NpFeGa
  • NpNiGa
  • NpRhGa
  • Specific heat
  • Transuranium compound


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