Spin and orbital moments in actinide compounds (invited)
- Physics Department, Riso National Laboratory, DK-4000 Roskilde, Denmark (DK)
- Commission of the European Communities, Joint Research Centre, Institute for Transuranium Elements, Postfach 2340, FRG-7500 Karlsruhe, (Federal Republic of Germany)
The extended spatial distribution of both the transition-metal 3{ital d} electrons and the actinide 5{ital f} electrons results in a strong interaction between these electron states when the relevant elements are alloyed. A particular interesting feature of this hybridization, which is predicted by single-electron band-structure calculations, is that the orbital moments of the actinide 5{ital f} electrons are considerably reduced from the values anticipated by a simple application of Hund's rules. To test these ideas, and thus to obtain a measure of the hybridization, we have performed a series of neutron scattering experiments designed to determine the magnetic moments at the actinide and transition-metal sublattice sites in compounds such as UFe{sub 2}, NpCo{sub 2}, and PuFe{sub 2} and to separate the spin and orbital components at the actinide sites. The results show, indeed, that the ratio of the orbital to spin moment is reduced as compared to the free-ion expectations. In addition there is qualitative agreement with theory, although the latter predicts values of both components that are larger than those found by experiment. Because {bold L} and {bold S} are opposed in the light actinides, and {ital L} is usually greater than {ital S}, the reduction of {ital L} can result in a situation for which {ital L}{minus}{ital S}{congruent}0. This almost occurs in UFe{sub 2}. However, neutrons are capable of observing the individual components at finite wave vector ({bold Q}), although the total component (observed at {bold Q}={bold 0}) may indeed be close to zero.
- OSTI ID:
- 5564551
- Journal Information:
- Journal of Applied Physics; (USA), Journal Name: Journal of Applied Physics; (USA) Vol. 69:8; ISSN 0021-8979; ISSN JAPIA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360104* -- Metals & Alloys-- Physical Properties
ACTINIDE ALLOYS
ALLOYS
ANGULAR MOMENTUM
COBALT ALLOYS
COHERENT SCATTERING
DIFFRACTION
HYBRIDIZATION
IRON ALLOYS
MAGNETIC MOMENTS
NEPTUNIUM ALLOYS
NEUTRON DIFFRACTION
ORBITAL ANGULAR MOMENTUM
PARTICLE PROPERTIES
PLUTONIUM ALLOYS
SCATTERING
SPIN
TRANSITION ELEMENT ALLOYS
URANIUM ALLOYS