Phase-locking of driven vortex lattices with transverse ac force and periodic pinning - art. no. 134508

For a vortex lattice moving in a periodic array we show analytically and nu merically that a new type of phase locking occurs in the presence of a long itudinal dc driving force and a transverse ac driving force. This phase loc king is distinct from the Shapiro step phase locking found with longitudina l ac drives. We show that an increase in critical current and a fundamental phase-locked step width scale with the square of the driving ac amplitude. Our results should carry over to other systems such as vortex motion in Jo sephson-junction arrays.