Itinerant 5f electrons and the Fermi surface properties in neptunium compounds

Abstract We grew high-quality single crystals of NpGe 3 , NpIn 3 , NpCoGa 5 , NpRhGa 5 and NpFe 4 P 12 by the flux method, and measured the de Haas-van Alphen (dHvA) effect, magnetic susceptibility and resistivity. The results of dHvA experiments in NpGe 3 , NpCoGa 5 and NpRhGa 5 were well explained by the energy band calculation based on the 5f-itinerant model, while the topology of Fermi surfaces in NpIn 3 is similar to those of LaIn 3 , implying the 5f-localized nature of NpIn 3 . The skutterudite compound NpFe 4 P 12 is a low carrier system with the 5 f 3 configuration.