Effect of intraionic coupling on anisotropic interaction in actinide compounds: L-S and j-j coupling in Pu compounds

An interionic interaction arising from the hybridization of moderately delocalized f electrons with the band electrons is central in determining the magnetic behavior of cerium and light actinide monopnictides and monochalcogenides. Siemann and Cooper first recognized this in the case of the Ce3+( f 1) systems, and used the Coqblin–Schrieffer (CS) treatment of the hybridization for the f 1 ion in seeing how the Ce3+ ions are coupled to one another via their mutual hybridization with the bands. We have extended the Siemann–Cooper theory to the case of ions with more than one f electron (e.g., U3+, U4+, Pu3+). In our theory, the angular dependence of the two-ion interaction depends on the f occupation number and on the type of intraionic coupling. Here we provide a detailed exposition of the theory, and report on a new and important application to understanding the behavior of plutonium compounds.