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The inverse susceptibilities of the monopnictides and monochalcogenides of the light rare earths plotted against temperature flatten off at high temperatures. This behaviour is well explained by Van Vleck paramagnetism of the excited states of the multiplet. For almost all actinide pnictides and chalcogenides a similar flattening-off is observed. Since spin orbit coupling is much stronger than in the light rare earth compounds an analogous interpretation is not possible. Susceptibility curves for uraniun compounds can be fitted by adding a temperature dependent enhanced Pauli paramagnetism to the Curie-Weiss term (modified Curie-Weiss law). The high temperature susceptibility behaviour of neptunium compounds is very similar to the one of uranium compounds (ie an appreciable deviation from the Curie-Weiss law is only visible for the chalcogenides). The plutionum chalcogenides show a temperature independent paramagnetism, which can be explained either by a model of mixed valency, or by enhanced Pauli paramagnetism of non-bond f-electrons. Americium compounds show large temperature-independent susceptibility up to room temperature. This is unexplained as yet.

Additional information

Authors: VOGT O, ETHZ, Laboratorium für Festkörperphysik, Zürich (CH);MATTENBERGER K, ETHZ, Laboratorium für Festkörperphysik, Zürich (CH);LÖHLE J, Paul Scherrer Institute, HSK, Villigen (CH);REBIZANT J, JRC Karlsruhe (DE)
Bibliographic Reference: Paper presented: Actinides '97, Baden-Baden (DE), 21-26 September 1997
Availability: Available from (1) as Paper EN 41104 ORA
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