Soft-X-ray Magnetic Circular Dichroism under Pulsed High Magnetic Fields at EuM4,5Edges of Mixed Valence Compound EuNi2(Si0.18Ge0.82)2

By applying our new experimental technique of X-ray absorption spectroscopy (XAS) and its X-ray magnetic circular dichroism (XMCD) in the soft-X-ray region under high pulsed magnetic fields of up to 21.3 T, we measured the XAS and XMCD spectra at the Eu M 4,5 edges of EuNi 2 (Si 0.18 Ge 0.82 ) 2 . The measured spectra are analyzed by taking into account the atomic multiplet structures to clarify the mixed valence properties, which are caused by the hybridization between Eu 2+ and Eu 3+ configurations. We obtain the field dependence of the average valence number from the XAS spectra and that of the magnetizations of Eu 2+ and Eu 3+ components separately using the spin and orbital sum rules from the XMCD spectra. These results are in good agreement with theoretical ones calculated with a modified single-impurity Anderson model. The present study reveals the key to solving a puzzling problem that was posed in previous XAS and XMCD experiments in the hard-X-ray region.