Crystal Structure and Physical Properties of Trigonal NpGa₃and Np₃Ga₁₁

Abstract

We have investigated Np-Ga binary phase diagram by the Ga-flux method. We found a new structure type of NpGa 3 with the trigonal R3m, instead of the previously reported cubic AuCu 3 -type NpGa 3 . This compound orders ferromagnetically at 71 K with a saturation moment 1.55 µ B /Np with a strong uniaxial anisotropy along the [001] direction. From the structural point of view, the AuCu 3 -type atomic arrangements are well maintained in the R3m structure where the trigonal [001] corresponds to the cubic [111] direction. The uniaxial magnetic anisotropy in trigonal-NpGa 3 is consistent with that of cubic NpGa 3 along [111], suggesting that the magnetic anisotropy is governed by the local crystal field effects. We also found a new compound Np 3 Ga 11 and its crystal structure is reported.

Single Crystal Growth and Magnetic Anisotropy of Hexagonal PuGa3

“…4. The similar situation occurs in cubic NpGa 3 and trigonal NpGa 3 [6]. In the 115-type heavy fermion superconductors, magnetic fluctuation plays a important role in the pairing interaction.…”