Calculation of low-energy-electron lifetimes

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 approximat ions to the real density of states of metals have been used allowing analyt ical results, which show that the free-electron scaling (E-E-F)(-2) Of the lifetime is affected above the onset of d-electron contributions. Hence, in noble metals a scaling with (E-E-F-omega(d))(-2), where omega(d) is the en ergy 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 life times of majority and minority spin electrons is found energy independent b elow the threshold for the excitation of majority d electrons while this ra tio increases with energy above that point.