  Domain wall motion driven by ultra-short laser pulses is a prerequisite for
envisaged low-power spintronics combining storage of information in magneto
electronic devices with high speed and long distance transmission of
information encoded in circularly polarized light. Here we demonstrate the
conversion of the circular polarization of incident femtosecond laser pulses
into inertial displacement of a domain wall in a ferromagnetic semiconductor.
In our study we combine electrical measurements and magneto-optical imaging of
the domain wall displacement with micromagnetic simulations. The optical spin
transfer torque acts over a picosecond recombination time of the spin polarized
photo-carriers which only leads to a deformation of the internal domain wall
structure. We show that subsequent depinning and micro-meter distance
displacement without an applied magnetic field or any other external stimuli
can only occur due to the inertia of the domain wall.
