Synchrotron radiation as a probe of actinide magnetism (T7-Al 'Magnetism')

Polarized beam experiments using synchrotron sources provide a direct measurement of both the orbital- and the spin-angular momentum densities. Similar information can be obtained by applying sum rules for the integral of the imaginary part of the forward-scattering amplitude over two spin-orbit split absorption edges to magnetic circular dichroism (MCD) measurements in ferri- and ferromagnetic materials. Large enhancements of the cross section for magnetic scattering at the MIV and MV absorption edges have led to studies of the weak critical scattering above magnetic phase transitions and of the order parameter in heavy fermion systems which have very small moments. These enhancements have also enabled studies of the modification of magnetic order in the near surface regions of crystals where the crystal symmetry is broken. (orig.)