Résumé
The ultrafast electron dynamics subsequent to a hundred femtosecond photo-excitation is monitored in a few nanometer thick Au/Co/Au film by means of time-resolved transient spectroscopy. We show that the insertion of the thin Co layer in the Au film leads to a drastic modification of the scattering rates of the different thermalization regimes. The electron-electron interactions are dominated by the mobile sp-electrons scattering on the heavy d-electrons, which concomitantly enhances the electron-phonon interactions by up to a factor of 5. In the framework of ultrafast magnetization dynamics, this study provides important data on the electronic processes underlying the spin dynamics in a sample typically designed for magneto-optical applications.