Magnetic reversal under external field and current-driven domain wall   motion in (Ga,Mn)As: influence of extrinsic pinning
  We investigate the anisotropy of magnetic reversal and current-driven domain wall motion in annealed Ga_0.95Mn_0.05As thin films and Hall bar devices with perpendicular magnetic anisotropy. Hall bars with current direction along the [110] and [1-10] crystallographic axes are studied. The [110] device shows larger coercive field than the [1-10] device. Strong anisotropy is observed during magnetic reversal between [110] and [1-10] directions. A power law dependence is found for both devices between the critical current (JC) and the magnetization (M), with J_C is proportional to M^2.6. The domain wall motion is strongly influenced by the presence of local pinning centres. 
K Y Wang, A C Irvine, J Wunderlich, K W Edmonds, A W Rushforth, R P   Campion, C T Foxon, D A Williams and B L Gallagher