Orbital and spin moments in uranium compounds from X-ray magnetic circular dichroism

The knowledge of the orbital (mu(L)) and spin (mu(S)) magnetic moments of a magnetic material is fundamental for the understanding of its basic properties. X-ray Magnetic Circular Dichroism (XMCD) at the uranium M-edges (3.5-3.8 keV) of a ferromagnet is a new tool which provides a direct and independent determination of mu(L) and mu(S) using sum rules. Here we report on recent XMCD experiments performed on uranium compounds with different degree of hybridization USb0.5Te0.5 (localized), UFe2 (strongly hybridized) and US (weakly hybridized). The results are compared to those obtained from the analysis of the magnetic form factor deduced from neutron scattering experiments. The importance of the value assigned to the magnetic spin dipolar operator < T-2> is emphasized. (C) 1998 Elsevier Science S.A.