Spin and orbital moments in actinide compounds
The extended spatial distribution of both the transition metal 3d-electrons and the actinide 5f-electrons results in a strong interaction between these electron states when the relevant elements are alloyed. A particular interesting feature of this hybridisation, which is predicted by single-electron band-structure calculations, is that the orbital moments of the actinide 5f-electrons are considerably reduced from the values anticipated by a simple application of Hund's rules. These ideas have been tested, giving a measure of the hybridisation, in a series of neutron scattering experiments which determine the magnetic moments at the actinide and transition metal sublattice sites in compounds such as UFe(2), NpCo(2) and PuFe(2), and separate the spin and orbital components at the actinide sites. The results show that the ratio of the orbital to spin moment is reduced 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 L and S are opposed in the light actinides, and L is usually greater than S, the reduction of L can result in a situation for which L - S is close to zero. This almost occurs in UFe(2). However, neutrons are capable of observing the individual components at finite wave vector (Q), although the total component (observed at Q=0) may indeed be close to zero.
Bibliographic Reference: Paper presented: 35th Annual Conference on Magnetism and Magnetic Materials, San Diego (US), Oct. 29 - Nov. 1, 1990
Availability: Available from (1) as Paper EN 35616 ORA
Record Number: 199011595 / Last updated on: 1994-12-02
Original language: en
Available languages: en