  Disorder in ultra-thin magnetic films can significantly hinder domain wall
motion. One of the main issues on the path towards efficient domain wall based
devices remains the characterization of the pinning landscape at the nanoscale.
In this paper, we study domain wall motion in W/CoFeB/MgO thin films with
perpendicular magnetic anisotropy crystallized by annealing at 400$^{\circ}$C
and a process based on He$^{+}$ irradiation combined with elevated
temperatures. Magnetic properties are similar for the whole series of samples,
while the magnetic domain wall mobility is critically improved in the
irradiated samples. By using an analytical model to extract nanoscale pinning
parameters, we reveal important variations in the disorder of the crystallized
samples. This work offers a unique opportunity to selectively analyze the
effects of disorder on the domain wall dynamics, without the contribution of
changes in the magnetic properties. Our results highlight the importance of
evaluating the nanoscale pinning parameters of the material when designing
devices based on domain wall motion, which in return can be a powerful tool to
probe the disorder in ultra-thin magnetic films.
