Magnetization reversal triggered by spin-polarized current in magnetic nanowires

It is shown experimentally that a pulsed current driven through a Ni nanowire provokes an irreversible magnetization reversal at a field differing from the spontaneous switching field H_sw by ΔH of as much as 40% of H_sw. The state of the magnetization is assessed by anisotropic magnetoresistance measurements carried out on single, isolated nanowires with and without spin polarizer (Co/Cu multilayers). The parameter ΔH is studied as a function of the angle θ between the applied field and the wire. A shift of about 90° between both profiles ΔH(θ) with and without spin polarizer shows that the observed effect is related to the spin polarization of the current. The results are interpreted with a model of generalized Landau-Lifshitz-Gilbert equation with spin-polarized current.