  We have studied current-driven domain wall motion in modified
Ga_0.95Mn_0.05As Hall bar structures with perpendicular anisotropy by using
spatially resolved Polar Magneto-Optical Kerr Effect Microscopy and
micromagnetic simulation. Regardless of the initial magnetic configuration, the
domain wall propagates in the opposite direction to the current with critical
current of 1~2x10^5A/cm^2. Considering the spin transfer torque term as well as
various effective magnetic field terms, the micromagnetic simulation results
are consistent with the experimental results. Our simulated and experimental
results suggest that the spin-torque rather than Oersted field is the reason
for current driven domain wall motion in this material.
