AN INVESTIGATION OF URANIUM M(4,5) EDGE MAGNETIC-X-RAY CIRCULAR-DICHROISM IN US

Magnetic x-ray circular dichroism (MXCD) has been measured in a ferrom agnetic uranium monosulphide crystal by monitoring the fluorescence si gnal over the uranium M(4,5) edges. Despite sizeable absorption correc tions, we have obtained a precise value of the dichroic branching rati o, which is compared with sum-rule predictions. We find that, in contr ast to the case of cubic 3d transition metals where the magnetic dipol e term (T-z) can be neglected, its contribution to the dichroism signa l in the present case is larger than that of the spin polarization, (S -z). The dichroism spectrum is shown to exhibit considerably more stru cture than those of resonant magnetic diffraction from antiferromagnet ic actinide compounds, and is found to be in good qualitative agreemen t with atomic calculations of 5f(2) and 5f(3) configurations.