Modulation of propagation characteristics of spin waves induced by perpendicular electric currents

We have theoretically and numerically investigated the effect of perpendicular currents on the propagation characteristics of spin waves on a wire composing the free layer of a spin valve. Our theory shows that the single Slonczewski's spin-transfer torque can cause the spin-wave Doppler effect and modify the spin-wave attenuation and that the fieldlike torque makes negligible contribution due to its relatively small magnitude. Micromagnetic simulations confirm these theoretical predictions and further reveal that spin waves at suprathreshold currents are instable and become chaotic with increased time. Finally, selective tuning of the spin-wave attenuation is demonstrated by using local, individual currents. (C) 2009 American Institute of Physics. [doi: 10.1063/1.3243687]