The relaxation processes of electrons and spins systems following the absorption of femtosecond optical pulses in ferromagnetic nickel have been studied using optical and magneto-optical pump-probe techniques. The magnetization of the film drops rapidly during the first picosecond, but different electron and spin dynamics are observed for delays in the range 0–5 ps. The experimental results are adequately described by a model including three interacting reservoirs (electron, spin, and lattice).

• Received 17 October 1995

DOI:https://doi.org/10.1103/PhysRevLett.76.4250