Current-induced magnetic domain wall motion has been investigated in microtracks made from a ferromagnetic semiconductor (Ga,Mn)As thin film with perpendicular anisotropy. In order to reveal the nature of this motion, small fields were additionally applied. The results demonstrate that, when driven by a low current density, the domain walls move under weak fields in a steady-state regime, ruling out models based on spin precession of the domain wall magnetization. The interpretation of these results requires a nonadiabatic contribution in the spin transfer, whose value is estimated and compared to recent theoretical calculations. This highlights the role of spin-orbit interaction in the carrier band on spin-transfer torque in continuous magnetic structures.

• Received 12 October 2009

DOI:https://doi.org/10.1103/PhysRevB.80.193204