Signal propagation in time-dependent spin transport
  This paper analyzes theoretically the signal propagation in spin transport by modulating the current passing through magnetic multilayers. Using a macroscopic description of spin transport based on the dynamical Boltzmann equation, we show that time-dependent spin transport possesses a wave-like character that leads to modifications of pure spin-diffusion dynamics. In particular, the wave-like characteristics allow one to extract a finite spin signal-propagation velocity. 
Yao-Hui Zhu, Burkard Hillebrands, and Hans Christian Schneider