Valence Instability and Magnetic Polarization of Ce Atoms near the Interface of Ce/Fe Multilayers Studied by Magnetic Circular X-Ray Dichroism.

An experimental study of conventional x-ray absorption and of magnetic circular x-ray dichroism has been performed on Ce/Fe Multilayers at the Ce L2,3 and the Fe-K edge, to characterize the impact of the interaction of Ce and Fe on the local electronic and magnetic structure of the interface. The spectra reveal that the interaction has two effects. First, on a depth scale of up to 15 A near the interface, the Ce atoms adopt the electronic structure of the oc-phase, with itinerant 4f states. Second, a large portion (=10 A) of these cc-like Ce atoms is magnetically polarized and carries an ordered Magnetic 5d Moment. The Fe-3d and Ce-5d Moments are antiferromagnetically coupled. Interface Mixing on a length scale of the magnetic polarization can be excluded.