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Neptunium monochalcogenides crystallise in the simple rocksalt structure. Electrical resistivity measurements on NpS, NpSe and NpTe single crystals have been performed in the temperature range 1.5 to 300 K; partial results on NpTe have already been published. In all three compounds the Kondo effect is present in the paramagnetic range, evidencing competition between intra-atomic Kondo interaction and inter-atomic exchange. However, NpS and NpSe are antiferromagnetically ordered at low temperature while only short range ordering takes place in NpTe. In NpSe, below T(N) = 41 K, rho goes through a minimum at 28 K then rises down to the lowest temperature. In NpS, the magnetic ordering at T(N) = 23 K is first order, and below T(N) rho increases very rapidly. Thus, as in plutonium monochalcogenides, hybridised f-d quasiparticles are formed via strong Kondo intra-atomic correlations. The low T increase in resistivity is probably due to the gap opening, and may be enforced by the type II magnetic ordering. Kondo compensation may also be the cause of moment reduction as well as rho increases, when going from Te to S through Se.

Additional information

Authors: FOURNIER J M, CEN, DRF/SPh-MDN, Grenoble (FR);PLESKA E, CEN, DRF/SPh-MDN, Grenoble (FR);CHIAPUSIO J, CEN, DRF/SPh-MDN, Grenoble (FR);REBIZANT J, JRC Karlsruhe (DE);SPIRLET J C, JRC Karlsruhe (DE);VOGT O, ETH, Laboratorium für Festkörperphysik, Zürich (CH)
Bibliographic Reference: Paper presented: 21e Journées des Actinides, Montechoro (PT), April 28 - May 1, 1991
Availability: Text not available
Record Number: 199111259 / Last updated on: 1994-12-02
Original language: en
Available languages: en
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