We have studied numerically the dynamics of a directed elastic string in a two-dimensional array of quenched random impurities. The string is driven by a constant transverse force and thermal fluctuations are neglected. There is a transition from pinned to unpinned behavior at a critical value FT of the driving force. At the transition the average string velocity scales with the driving force. The scaling is equally well described by a power law vd∼(F-FT)ζ, with ζ=0.24±0.1, or by a logarithm, vd∼1/ln(F-FT). The divergence of the velocity-velocity correlation length at threshold is characterized by an exponent ν=1.05±0.1.
ASJC Scopus subject areas
- Physics and Astronomy(all)