Possibility of the Solid-Fluid Transition in Moving Periodic Systems

The steady sliding state of periodic structures such as charge density waves and flux line lattices is numerically studied based on the three dimensional driven random field XY model. We focus on the dynamical phase transition between plastic flow and moving solid phases controlled by the magnitude of the driving force. By analyzing the connectivity of co-moving clusters, we find that they percolate the system within a finite observation time under driving forces larger than a certain critical force. The critical force, however, logarithmically diverges with the observation time, i.e. the moving solid phase exhibits only within a certain finite time, which exponentially grows with the driving force.