Domain wall motion by spin-polarized current: a micromagnetic study

The effect of a spin-polarized current crossing a domain wall in a thin and narrow Permalloy(TM) strip is studied by micromagnetic simulations, supported by a one-dimensional model of wall dynamics. We use the simplest way to incorporate the spin-polarized current effect in the micromagnetic formalism; namely, a local momentum transfer under the assumption that the current polarization is in local equilibrium. We predict current influence on wall velocity and mobility under field. However, in order to reach agreement with recent experiments, more than ten times larger currents would be required within this simplest model. Thus, more elaborate models of spin transfer are needed. (C) 2004 American Institute of Physics.