X-ray magnetic circular dichroism (XMCD) measurements were performed at the U $M_{4,5}$ edges for $\mathrm{U}∕\mathrm{Fe}$, $\mathrm{U}∕\mathrm{Co}$, $\mathrm{U}∕\mathrm{Ni}$, and $\mathrm{U}∕\mathrm{Gd}$ multilayers. In the case of the $\mathrm{U}∕\mathrm{Fe}$ system, a significant polarization of the $\mathrm{U}5f$ electrons was found, but not for $\mathrm{U}∕\mathrm{Co}$ or $\mathrm{U}∕\mathrm{Ni}$ multilayers. We ascribe this to a hybridization of $\mathrm{U}5f$ and $\mathrm{Fe}3d$ states, which overlap in energy near the Fermi level. In the $\mathrm{U}∕\mathrm{Gd}$ system, the XMCD signals were small and yielded magnetic moments of order $0.02{\mu }_B$. The spatial extent of the $\mathrm{U}5f$ polarization is different from that of the $\mathrm{U}∕\mathrm{Fe}$ system and is oscillatory, extending into the center of the U layers.

• Received 19 November 2007

DOI:https://doi.org/10.1103/PhysRevB.77.064423