Browsing by Author "Raoux, D."

The element and electronic shell specificities of X-ray resonant magnetic scattering have been used to investigate the magnetization of Ce 5d and Fe 3d states in [CeH2(19.6 Angstrom) /Fe (25.4 Angstrom)] 38 a multilayer. We show that the measurement of the magnetic contribution to the intensities reflected at low angles at the Ce L-2 and Fe L-2,(3) edges allows us to investigate the profile of the Ce 5d and Fe 3d magnetic polarization. The Fe 3d polarization is found to be uniform across the Fe layer and the Ce 5d polarization appears to be restricted close to the interface with Fe.

The in-depth distribution of the induced 5d magnetic moments across the Ce layers in Fe/Ce/La/Ce, Fe/La/Ce/La and Fe/CeH2-delta multilayers has been investigated by x-ray resonant magnetic scattering (XRMS) at the Ce L-2 edge. The determination of the composition profile across the period of the multilayer is required for a quantitative analysis of XRMS and has been derived from x-ray resonant reflectivity measurements. In Fe/Ce/La/Ce and Fe/La/Ce/La multilayers, Ce adopts an alpha-like electronic configuration and the local magnetization, across the Ce layer, is found to be highly nonuniform. The Ce 5d magnetic profile shows an oscillating behavior with an amplitude decreasing from the Fe interface in Fe/Ce/La/Ce. Conversely, in Fe/La/Ce/La, where the Ce atoms are not in direct contact with Fe atoms, it presents an oscillatory profile with, however, a nearly constant amplitude. In Fe/CeH2-delta multilayers, where hydrogen leads to a strain relaxation and to a 4f relocalization (Ce gamma-like configuration), a nonoscillating decreasing profile has been observed. These experiments allow one to evidence an antiferromagnetic component in a alpha Ce ultrathin layer and a sharply decreasing induced magnetization due to 5d-3d hybridization at the interface.

The distribution of the induced 5d magnetic moments across the Ce layers in [CeLaCe/Fe](57) and [LaCeLa/Fe](57) multilayers has been investigated by resonant X-ray magnetic reflectivity. The quantitative analysis of the energy dependence of the asymmetry ratios measured on top of several multilayer Bragg peaks required the determination of the composition profile across the period of the multilayer. In order to separate out the structural parameters of the Ce and La layers, resonant X-ray reflectivity measurements were carried out at the La and Ce L-edges as well as at the Fe K-edge. The induced Ce 5d magnetic profile which is derived from the XRMS spectra is found to oscillate in both samples, with however, a different depth dependence probably related to the influence of the different interfaces. (C) 2000 Elsevier Science B.V. All rights reserved.

We report on X-ray resonant magnetic reflectivity (XRMR) at the Ce L-2 and M-4,M-5 edges in an ex-situ grown Fe/Ce multilayer. We show that the measurement of the magnetic contribution to the intensities reflected at low angles allows us to investigate the profile of the Ce 5d and 4f magnetization. The calculated XRMR signals indicate that the Ce moments have a non-collinear structure.