The role of orbital polarization and correlation effects in the magneto-optic behavior of CeSb and CeTe

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Abstract
CeSb and CeTe show giant magneto‐optic Kerr rotations and also have extremely unusual magnetic ordering properties. CeSb shows peculiar and extraordinarily anisotropic antiferromagnetic behavior; while CeTe shows an ordered moment and TN only 15% that of CeSb, indicative of incipient heavy‐fermion behavior. This has been understood in an absolute theory of orbitally driven correlated f‐electron magnetism. We seek to understand the giant magneto‐optic properties including the role, if any, of explicit correlation effects not captured by an exchange‐correlation potential. To this end we have performed full potential linearized muffin‐tin orbital polarized band calculations for the optical conductivity tensor, first only spin polarized (orbital polarization only via spin‐orbit coupling) and second with explicit orbital polarization. As expected, for CeSb and CeTe the spin‐polarized calculation gave the diagonal, ordinary optical, conductivity in good agreement with experiment; but the off‐diagonal, magneto‐optic, behavior was in poor agreement; and the ordered moment was much different from experiment. For the spin‐and‐orbitally polarized calculation, the ordered moment agreed reasonably well with experiment for CeSb but very poorly for CeTe. However, the magneto‐optic behavior remained distinctly different from experiment for both materials. Thus as anticipated, explicit correlation effects associated with differing discrete f‐configuration energies appear to be a central aspect of giant magneto‐optic behavior.