Magnetic susceptibility of DHCP NpPd3

We have measured the magnetic susceptibility and magnetisation of the double-hexagonal close-packed (DHCP) phase of NpPd3 from T=2-300K in magnetic fields up to 7T. Our results clearly indicate the presence of two phase transitions in this compound, at 10 and 30K. At higher temperatures, the susceptibility exhibits Curie-Weiss behaviour, with an effective moment of 2.8μB/Np atom. This result implies that the Np ions are trivalent, with a 5f4 electronic configuration. Below the 30K transition, the magnetisation of NpPd3 displays hysteresis in fields below 0.1T with a residual ferromagnetic moment of the order of 0.06μB/Np atom