Resonant Magnetic X-Ray Scattering in UAs
Resonant enhancement of the magnetic x-ray scattering cross-section in 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 of the (0, 0, 2) reflection. At the M sub V and M sub (III) edges the enhancements are 10 sup 5 and 50, respectively. The dramatic enhancement at M edges has been predicted and arises from electric multipole transitions between atomic core states and exchange-split Fermi edge states. The polarization dependence of the magnetic scattering agrees with the selection rules for such transitions.