Dynamical Phases of Driven Vortex Systems

We study numerically the motion of vortices in dirty type II superconductors. In two dimensions at strong driving currents, vortices form highly correlated ``static channels.'' The static structure factor exhibits convincing scaling behavior, demonstrating quasi-long-range translational order in the transverse direction. However, order in the longitudinal direction is only short range. We clearly establish the existence of a finite transverse critical current, suggesting strong barriers against transverse driving forces. We discuss these results in terms of recently proposed theories of the moving vortex systems.