The propagation of a domain wall in a submicron ferromagnetic spin-valve stripe is investigated using giant magnetoresistance. A notch in the stripe efficiently traps an injected wall stopping the domain propagation. The authors show that the magnetic field at which the wall is depinned displays a stochastic nature. Moreover, the depinning statistics are significantly different for head-to-head and tail-to-tail domain walls. This is attributed to the dipolar field generated in the vicinity of the notch by the pinned layer of the spin valve.
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If the injection field is too high, it is possible that the domain wall is not trapped during its propagation. 91% of the cycles present a well define pinning of the domain wall (depinning and injection field differ by more than ) for transition. This proportion decreases to 62% for the propagation, due to the lower depinning fields.
