Modification of Spin Wave Propagation by Current Injection

We studied the effect of an electric current on the spin wave propagation in magnetic wires, and found the following two effects. (i) Current injection changes the velocity of spin wave; the velocity is increased or decreased depending on the current polarity. (ii) Current injection modifies the attenuation length of spin wave; the attenuation length of spin wave can increase when the spin waves and electrons move in the same direction. The first finding can be interpreted as the time-domain observation of the spin-wave Doppler shift by current injection [1]. The second effect is thought to be affected by the nonadiabaticity of the spin transfer torque and thus can be used to estimate the nonadiabaticity [2]. \\[4pt] [1] V. Vlaminck and M. Bailleul, Science 322, (2008) 410. \\[0pt] [2] S. M. Seo, K. J. Lee, H. Yang, and T. Ono, Phys. Rev. Lett. 102, (2009) 147202.