  Current-induced magnetic domain wall motion at zero magnetic field is
observed in the permalloy layer of a spin-valve-based nanostripe using
photoemission electron microscopy. The domain wall movement is hampered by
pinning sites, but in between them high domain wall velocities (exceeding 150
m/s) are obtained for current densities well below $10^{12} \unit{A/m^2}$,
suggesting that these trilayer systems are promising for applications in domain
wall devices in case of well controlled pinning positions. Vertical spin
currents in these structures provide a potential explanation for the increase
in domain wall velocity at low current densities.
