Profile of the induced<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mn>5</mml:mn><mml:mi>d</mml:mi></mml:math>magnetic moments in Ce/Fe and La/Fe multilayers probed by x-ray magnetic-resonant scattering

The element and electronic shell selectivity of x-ray resonant magnetic scattering (XRMS) has been used to investigate the profile of the spin polarization of the $5d$ electronic states of Ce and La across the rare-earth layers in Ce/Fe and La/Fe multilayers. The magnetic contributions to the diffracted intensities have been measured at low angles, at the ${L}_{2}$ edge of the rare earth. In agreement with previous results from x-ray magnetic circular dichroism (XMCD) experiments, the La $5d$ polarization is found to be localized right at the interfaces with the Fe layers, as it is expected from a direct hybridization with the Fe $3d$ states. In the case of Ce/Fe multilayers where Ce is in an \ensuremath{\alpha}-like electronic state with a complex behavior of the $5d$ magnetic polarization, the XRMS results obtained for two samples with 10 and 22 \AA{} thick Ce layers indicate that the Ce $5d$ polarization decreases slowly from the interfaces towards the center of the layers. This is in agreement with previous XMCD results. However, at least for the two samples which have been investigated, XRMS also suggests that the Ce $5d$ polarization oscillates across the Ce layer with a period equal to the (111) interplanar distance in \ensuremath{\alpha} fcc Ce. Though compatible with the XMCD findings, this oscillating behavior cannot be derived from its dependence on the Ce layer thickness because of the decrease of the magnetic polarization which prevents us from observing changes in the sign of the XMCD amplitude.