An investigation of uranium M4,5 edge magnetic X-ray circular dichroism in US

Magnetic X-ray circular dichroism (MXCD) has been measured in a ferromagnetic uranium monosulphide crystal by monitoring the fluorescence signal over the uranium M4.5 edges. Despite sizeable absorption corrections, we have obtained a precise value of the dichroic branching ratio, which is compared with sum-rule predictions. We find that, in contrast to the case of cubic 3d transition metals where the magnetic dipole term (Tz) can be neglected, its contribution to the dichroism signal in the present case is larger than that of the spin polarization, (Sz). The dichroism spectrum is shown to exhibit considerably more structure than those of resonant magnetic diffraction from antiferromagnetic actinide compounds, and is found to be in good qualitative agreement with atomic calculations of 5f2 and 5f3 configurations. (authors)