Solid-state reaction in Ce/Ni multilayers studied by x-ray-absorption spectroscopy

Taking advantage of the high sensitivity of the Ce valence to the local environment, we investigated the early stage of the solid-state reaction in Ce/Ni multilayers through x-ray absorption spectroscopy. Ce $L_{\mathrm{III}}$-edge and Ni K-edge spectra have been compared to distributions of experimental spectra obtained from amorphous Ce-Ni alloys. Two possible diffusion profiles have been examined. It is found that the experimental data are compatible with the formation of a homogeneous amorphous-alloy interlayer instead of a Fickian profile.