Magnetic X-Ray Scattering in Uranium Compounds
Resonant enhancement of the magnetic x-ray scattering cross-section in antiferromagnetic UAs has been investigated by tuning the incident x-ray energy through the uranium M sub (III), M sub (IV) and M sub V absorption edges. At the M sub (IV) edge the intensity of the (0,0,5/2) magnetic reflection is enhanced by a factor of 10 sup 7 and is a remarkable 1% of the intensity at the (0,0,2). At the M sub V and M sub (III) edges the enhancements are 10 sup 5 and 50, respectively. Similar results are observed in the itinerant moment uranium pnictide, UN, where the large enhancement has been used to study the critical behavior of the magnetic order parameter. This large enhancement at the M absorption edges was predicted and arises from electric multipole transitions between core states and atomic-like, exchange-split Fermi-edge states.