Current-induced motion of a transverse magnetic domain wall in the presence of spin Hall effect

We theoretically study current-induced dynamics of a transverse magnetic domain wall in bi-layer nanowires consisting of a ferromagnetic layer on top of a nonmagnetic layer with strong spin-orbit coupling. Domain wall dynamics is characterized by two threshold current densities, J(th)(WB) and J(th)(REV), where J(th)(WB) is a threshold for the chirality switching of the domain wall and J(th)(REV) is another threshold for the reversed domain wall motion caused by spin Hall effect. Domain walls with a certain chirality may move opposite to the electron-flow direction with high speed in the current range J(th)(REV) < J < J(th)(WB) for the system designed to satisfy the conditions J(th)(WB) > J(th)(REV) and alpha > beta, where alpha is the Gilbert damping constant and beta is the nonadiabaticity of spin torque. Micromagnetic simulations confirm the validity of analytical results. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4733674]