  Pulsed current-induced magnetization reversal is investigated in the layer of
(Ga,Mn)(Bi,As) dilute ferromagnetic semiconductor (DFS) epitaxially grown under
tensile misfit strain causing perpendicular magnetic anisotropy in the layer.
The magnetization reversal, recorded through measurements of the anomalous Hall
effect, appearing under assistance of a static magnetic field parallel to the
current, is interpreted in terms of the spin-orbit torque mechanism. Our
results demonstrate that an addition of a small fraction of heavy Bi atoms,
substituting As atoms in the prototype DFS (Ga,Mn)As and increasing the
strength of spin-orbit coupling in the DFS valence band, significantly enhances
the efficiency of current-induced magnetization reversal thus reducing
considerably the threshold current density necessary for the reversal. Our
findings are of technological importance for applications to spin-orbit
torque-driven nonvolatile memory and logic elements.
