Site-selective magnetic order of neptunium in Np2Ni17

A. Hen (1, 2) , N. Magnani (1) , J. C. Griveau (1) , R. Eloirdi (1) , Eric Colineau (1) , Jean-Pierre Sanchez (3) , I. Halevy (2) , A. L. Kozub (4) , A. B. Shick (4) , I. Orion (2) , R. Caciuffo (1)

1 ITU - JRC Institute for Transuranium Elements [Karlsruhe]
2 BGU - Ben-Gurion University of the Negev
3 MDN - Magnétisme et Diffusion Neutronique
4 Institute of Physics [Prague]

We present the results obtained by superconducting quantum interference device (SQUID) magnetometry, specific heat, and Mossbauer spectroscopy measurements carried out on Np2Ni17 polycrystalline samples. We show that long-range magnetic order, with a moment mu((2b)) similar to 2.25 mu(B), occurs below T-N = 17.5 K on the Np (2b) sites. A nontrivial situation is observed in that the other Np sites (2d) do not take part to the order transition and carry only an induced moment of about 0.2 mu(B) below T-N. A combined analysis of the different experimental data sets allowed us to determine key parameters associated with the electronic structure of the system. The experimental results are discussed against first-principles electronic structure calculations based on the spin-polarized local spin density approximation plus Hubbard interaction.

Mots clés: Electronic-Properties; Neutron-Diffraction; Dirac-Fock; Ions; Intermetallics; Mossbauer; Er2Ni17

Domaines: Physique [physics]

A. Hen, N. Magnani, J. C. Griveau, R. Eloirdi, Eric Colineau, et al.. Site-selective magnetic order of neptunium in Np2Ni17. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2015, 92 (2), pp.024410. ⟨10.1103/PhysRevB.92.024410⟩. ⟨hal-01611026⟩