MAGNETIC STATES OF COBALT OXIDE AND FERRITES AND MAGNETIC DICHROISM IN 2P-3D X-RAY ABSORPTION-SPECTROSCOPY

It is shown that the recently observed magnetic circular dichroism (MCD) in Co 2p XAS for CoFe2O4 can be explained by assuming an orbital-moment and spin contribution of approximately 0.5 to 0.8-mu(B) and approximately 2.8-mu(B), respectively to the atomic moment for the Co2+ ion at 300 K under either an octahedral or a trigonal crystalline field on the basis of an atomic calculation. At lower temperatures, the effect of trigonal symmetry is predicted to be reflected in the MCD of CoFe2O4. The discussion is extended to the magnetic linear dichroism in Co 2p XAS for the antiferromagnet CoO with tetragonal distortions.