Structural, magnetic and transport properties of NpIrSn

Specific heat in NpNiSn and NpIrSn

“…2) confirms the two magnetic phase transitions at T N = 38 K and T 1 = 23.5 K, slightly different from transition temperatures originally deduced from magnetization data (T N = 40 K and T 1 = 22 K [4]). The transition at T 1 is clearly seen when subtracting ThIrSn data as represented in the inset of lower temperatures, indicating the antiferromagnetic character of the ordering.…”

“…Unfortunately, the lattice parameters a = 751.699(2) pm and c = 410.582 (2) pm, determined at the room temperature, are considerably different from those in NpIrSn (a = 735.0 pm and c = 397.5 pm [4]) or UIrSn (a = 734.6 pm and c = 401.2 pm [8]). The idea to use ThIrSn as an estimation for the lattice contribution to the specific heat in NpIrSn therefore should be taken with care.…”

“…ThIrSn was investigated as a possible non-magnetic analogue to NpIrSn. Previous magnetization and electrical resistivity measurements revealed that NpIrSn and NpNiSn order antiferromagnetically below T N = 40 and 37 K, respectively [4,5]. NpIrSn undergoes furthermore a second magnetic phase transition around T 1 22 K. The antiferromagnetic order in both compounds is not affected by magnetic fields up to 9 T. The 237 Np-Mössbauer spectroscopy yields the Np moments of 1.67 B in NpNiSn [5] whereas the Mössbauer spectra in NpIrSn are more complex suggesting several non-equivalent Np sites [6].…”

“…NpIrSn crystallizes in the hexagonal ZrNiAl-type structure [3,4] and NpNiSn in the orthorhombic structure of the TiNiSi-type * Corresponding author.…”

“…NpIrSn undergoes furthermore a second magnetic phase transition around T 1 22 K. The antiferromagnetic order in both compounds is not affected by magnetic fields up to 9 T. The 237 Np-Mössbauer spectroscopy yields the Np moments of 1.67 B in NpNiSn [5] whereas the Mössbauer spectra in NpIrSn are more complex suggesting several non-equivalent Np sites [6]. Complex incommensurate magnetic order in NpIrSn was revealed by powder neutron diffraction in both magnetic phases of NpIrSn [4].…”