title: Magnetic and electronic properties of NpFeGa5.
abstract: NpFeGa(5) single crystals prepared by the Ga-flux method have been investigated by magnetisation, specific heat and (237)Np Mössbauer spectroscopy measurements. An antiferromagnetic (AF) transition has been observed at T(N) ~114 K. The second AF transition which takes place at T* ~74 K has only been detected in the magnetisation data. A saturated ordered Np moment of 1.00(5) μ(B) and the occurrence of an Np(3 + ) charge state were inferred from the Mössbauer data. The angle between the Np ordered moment and the basal plane was shown to be ~17°, in good agreement with the value observed by neutron diffraction in the low temperature AF phase. The absence of change of the quadrupole interaction parameters at T* did not allow us to gain information on the Np moment reorientation at T*. The trend of the isomer shift along the NpTGa(5) series and the discrepancy between the Np moments determined by neutron diffraction and Mössbauer spectroscopy indicated a partial spatial delocalisation of the 5f electrons in NpFeGa(5).
authors: SPSMS, UMR-E CEA/UJF-Grenoble 1, INAC, Grenoble, France. jean-pierre.sanchez@cea.fr
authors: J P
authors: JP
authors: Sanchez
authors: D
authors: D
authors: Aoki
authors: R
authors: R
authors: Eloirdi
authors: P
authors: P
authors: Gaczyński
authors: J C
authors: JC
authors: Griveau
authors: E
authors: E
authors: Colineau
authors: R
authors: R
authors: Caciuffo