A-Type antiferromagnetic ordering and the transition of the 5 electronic state accompanied by unusual moment reorientation in NpRhGa

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

Elastic neutron scattering experiments have been carried out in order to reveal the magnetic structure and 5f electronic state of NpRhGa. This material exhibits two successive antiferromagnetic transition at T = 36 K and T = 33 K, respectively. A-type antiferromagnetic structure with the propagation vector q = (0 0 1/2) has been revealed below T. We found a remarkable change in the moment direction, namely the Np moment is parallel and perpendicular to the c-axis for T T T and T T, respectively. The magnetic moment exhibits a remarkable jump at T, indicating that the moment reorientation is associated with the change of 5f electronic state. The observed magnetic form factor indicates the dominant contribution of the orbital moment and revealed an itinerant character of the 5f electrons.