Magnetic structure study of NpTGa

Honda, Fuminori; Metoki, Naoto   ; Kaneko, Koji   ; Jonen, Shintaro; Aoki, Dai*; Homma, Yoshiya*; Yamamoto, Etsuji  ; Shiokawa, Yoshinobu*; Onuki, Yoshichika*

The discovery of the heavy fermion superconductivity below 19 K in PuCoGaproved that there is potential and fruitful field of interest spreading out in actinides science, where the quantum mechanical degrees of freedom of electron are playing a crucial role. Since AnTGa can be grown with various actinides and transition metal elements, it is an excellent candidate for studying the multiple electron system. Recently, we have extended our research activity into neutron scattering for NpGa (: Fe, Co, Ni and Rh) compounds in order to get deep insight about the multipolar degree of freedom in this system. We have revealed that NpGa exhibits various antiferromagnetic structures of A-, C-, G-type, ferromagnetic ordering and cant magnetism, which are the reminiscent of manganese perovskites. The remarkable successive magnetic transition associated with reorientation and considerable increase of magnetic moment found in NpNiGa and NpRhGa is a signature for the change in the electronic states, involving the possibility of the quadrupole order in itinerant system. We will sketch out a diverse electronic properties realized in NpGa in terms of the competing magnetic and quadrupolar interactions.