Ultrafast magnetization and spin oscillation in thin Ni/Fe film

We investigated the electron and spin dynamics in thin Ni/Fe film by means of time-resolved magneto-optical Kerr effect (MOKE). The magnetization of the film changes rapidly during the subpicosecond, including the spin relaxation and electron-phonon coupling. We observed the spin oscillations in the MOKE signal varying the polarization angle between the pump and probe beams. The period of the spin oscillations was about 200 fs. It is supposed that this is not only related to the polarization in film induced ultrafast optical field but mediated also the spin-obit coupling.