Electric dipole transitions from sharp, spin-orbit
split atomic core levels to spin polarized conduction bands result in very
large resonances in optical and magneto-optical properties. For the
technologically important 3d transition metal series (including Cr, Mn,
Fe, Co, and Ni) these core levels lie in the 500 - 1000 eV soft x-ray spectral
region. The nature of these resonances yields linear magneto-optical
effects much larger than in the near visible and other spectral regions,
and also brings element-specificity to magneto-optical measurements. While
these resonant magneto-optical effects present interesting challenges both
in their measurement and theoretical interpretation, they also present
many
opportunities to obtain important new information
about complex magnetic
materials. This talk will briefly review the
origins of these resonant
magneto-optical effects, and then review several applications
of these
effects involving x-ray Faraday and Kerr effect measurements,
microscopy, and scattering to study magnetic structure in heterogeneous
magnetic films of current technological interest