The effect of the density of states on the lifetime of low-energy electrons in metals has been studied using a golden rule approach. Simple approximations to the real density of states of metals have been used allowing analytical results, which show that the free-electron scaling (E−EF)−2 of the lifetime is affected above the onset of d-electron contributions. Hence, in noble metals a scaling with (E−EF−ωd)−2, where ωd is the energy distance from the Fermi energy to the top of the d band, appears once d electrons can be excited. In ferromagnetic Co, the ratio between the lifetimes of majority and minority spin electrons is found energy independent below the threshold for the excitation of majority d electrons while this ratio increases with energy above that point.

This project was supported by the Swedish Natural Science Research Council, Iberdrola S.A., Fundacion Altuna, the Ministerio de Educacion y Cultura (Spain), Eusko Jaurlaritza (Basque Country), and the University of the Basque Country.

Peer reviewed