TRADE-OFF BETWEEN INCREASED SIZE AND INCREASED BROADENING OF MAGNETOOPTIC EFFECTS IN CERIUM AND URANIUM SYSTEMS

f-electron magnetic ordering and associated magneto-optic effects depend on a complicated interplay of the degree of localization in real and energy space as affected by the coulomb interaction with pld band electrons and within the f-electrons. This interplay reflects the mixed and fluctuating nature of the f configuration. A relatively simple way to try to assess the resulting trade-off of size and broadening of magneto-optic effects, capturing some gross effects of correlations (f-f coulomb repulsion), is to use the LDA + U (coulomb repulsion energy) theory of Anisimov et al. We report the change this gives from bur previous LDA results in comparison to the experiments of Schoenes and coworkers for CeSb, CeTe, UTe, and US; and we discuss our view as to the apparent shortcomings of the LDA + U results. In assessing the prospects for an optimized trade-off of size and broadening of magneto-optic effects, calculations of hydrostatic pressure effects may be quite valuable. We discuss how the use and understanding of pressure effects can provide a paradigm for the variation of magnetic ordering and associated magneto-optic behavior possible between different compounds and alloys at ambient conditions.