Transverse pinning and vortex displacement fluctuations of moving vortex lattices interacting with periodic pinning

Abstract

The dynamical behavior of driven vortex lattices commensurate with periodic pinning in a clean superconducting film is investigated theoretically. A mean-field model, previously introduced by us [Phys. Rev. B 66 (2002) 054514] and called dynamical cage model, is applied here to study transverse pinning and vortex displacement fluctuations. The critical force for transverse depinning and the mean-square fluctuations induced by the temperature and vortex motion are calculated as functions of the vortex lattice center of mass velocity (or driving force) and of the temperature. The critical force is found to be in good qualitative agreement with numerical simulation results. The displacement fluctuations induced by vortex motion are found to be anisotropic, with the largest ones occurring along the direction of motion. Application of the Lindemann criterion to these fluctuations suggests a transition from the commensurate vortex lattice to a smectic vortex phase, also in agreement with numerical results.