Direct observation of domain-wall configurations transformed by spin   currents
  Direct observations of current-induced domain-wall propagation by spin-polarized scanning electron microscopy are reported. Current pulses move head-to-head as well as tail-to-tail walls in sub-micrometer Fe_{20}Ni_{80} wires in the direction of the electron flow, and a decay of the wall velocity with the number of injected current pulses is observed. High-resolution images of the domain walls reveal that the wall spin structure is transformed from a vortex to a transverse configuration with subsequent pulse injections. The change in spin structure is directly correlated with the decay of the velocity. 
M. Klaui, P.-O. Jubert, R. Allenspach, A. Bischof, J. A. C. Bland, G.   Faini, U. Rudiger, C. A. F. Vaz, L. Vila, C. Vouille