  Experimental measurements of domain wall propagation are typically
interpreted by comparison to reduced models that ignore both the effects of
disorder and the internal dynamics of the domain wall structure. Using
micromagnetic simulations, we study vortex wall propagation in magnetic
nanowires induced by fields or currents in the presence of disorder. We show
that the disorder leads to increases and decreases in the domain wall velocity
depending on the conditions. These results can be understood in terms of an
effective damping that increases as disorder increases. As a domain wall moves
through disorder, internal degrees of freedom get excited, increasing the
energy dissipation rate.
