Driven vortex lattices have been studied in Nb films, in which natural random pinning coexists with artificial ordered arrays of defects (submicrometric Ni dots). Three different dynamic regimes are found: for low vortex velocities, there is a plastic flow regime in which random defects frustrate the effect of the ordered array; then, for vortex velocities in the range 1–100 m/s, there is a sudden increase in the interaction between the vortex lattice and the ordered dot array, associated to the onset of quasi-long-range order in the vortex lattice; finally, at larger velocities the ordered array-vortex lattice interaction is suppressed again, in agreement with the behavior found in numerical simulations.

• Received 31 July 2001

DOI:https://doi.org/10.1103/PhysRevB.65.094509