  Spin currents have been shown to play a key role in the ultrafast
laser-driven demagnetization process in ferromagnetic thin films. Here, we show
that an oscillating spin current can be generated in the film via the
application of a femtosecond laser pulse in the visible range. In particular,
we prove that the spin current is due to ballistic electrons traveling back and
forth in the film. The dependence of the current intensity on the driving
electric field is also investigated.
