STRONG MAGNETIC CIRCULAR-DICHROISM AT THE M2,3 EDGES IN FERROMAGNETIC NI AND FERRIMAGNETIC FE3O4

Magnetic-circular-dichroism (MCD) spectra have been obtained at and around the M2,3 Core absorption edges in single crystals of ferromagnetic Ni and ferrimagnetic Fe3O4. Furthermore, strong MCD signals were observed for the weak multiplet structures of Fe3O4 in the prethreshold region. The experiments were performed using a bulk-sensitive reflection method by utilizing directly characterized, circularly polarized synchrotron radiation in conjunction with an ultrahigh-vacuum-compatible, i.e., bakable, superconducting magnet of special design. The present observation of a strong MCD not only provides a sensitive method for probing the local magnetic states of magnetic substances, but also could provide valuable information concerning the 3d electronic states of these materials.