Current-driven narrow domain wall depinning in perpendicular spin valves

We have studied the current-driven depinning processes for a narrow 12-nm wide one-dimensional Bloch domain wall (DW) in films exhibiting perpendicular magnetic anisotropy (PMA). High sensitivity magnetotransport measurements allow us to observe the motion of the narrow DW between pinned sites separated by /spl sim/20 nm. Thermal fluctuations are found to play a crucial role. A current-driven depinning force two to three orders of magnitude higher than has been seen in conventional in-plane systems is found, suggesting a more efficient spin transfer mechanism in our PMA system.