Ultrafast spin-dependent electron dynamics in fcc Co

The spin dependence of the lifetime of electrons excited in ferromagnetic cobalt is measured directly in a femtosecond real-time experiment. Using time-and spin-resolved two photon photoemission, we show that the lifetime of majority-spin electrons at 1 eV above the Fermi energy is twice as long as that of majority-spin electrons. The results demonstrate the feasibility of studying spin-dependant electron relaxation in ferromagnetic solids directly in the time domain and provides basis for understanding the dynamics of electron transport in ferromagnetic solids and thin films.