  Laser radiation incident on a ferromagnetic sample produces excited electrons
and currents whose spin polarization must not be aligned with the magnetization
-- an effect due to spin-orbit coupling that is ubiquitous in spin- and
angle-resolved photoemission. In this Paper, we report on a systematic
investigation of the dynamics of spin polarization and spin-polarized currents
produced by femtosecond laser pulses, modeled within our theoretical framework
EVOLVE. The spin polarization depends strongly on the properties of the laser
pulse and on the sample composition, as is shown by comparing results for
Cu(100), Co(100), and a Co/Cu heterostructure. We find a transition from
coherence before the laser pulse's maximum to incoherence thereafter. Moreover,
the time dependence of the spin-polarization components induced by spin-orbit
coupling differ significantly in Cu and Co: in Cu, we find long-period
oscillations with tiny rapid modulations, whereas in Co prominent rapid
oscillations with long period ones are superimposed. The pronounced spatial
dependencies of the signals underline the importance of inhomogeneities, in
particular magnetic/non-magnetic interfaces `act as source' for ultrafast
spin-polarization effects. Our investigation provides detailed insight into
electron dynamics during and shortly after a femtosecond laser excitation.
