Static friction as a function of waiting time probed by the dynamics of driven vortices in La_(2-x)Sr_xCuO_4 thin films

摘要

We systematically investigated the waiting-time dependence of the maximum static friction force, F_s(t_w), using the dynamics of driven vortices in a high-T_c superconductor as a model system. Fs(tw) was measured in La_(2-x) Sr_xCuO_4 thin films with different structures, sample sizes and pinning force. We found that F _s(t_w) by thermal fluctuation is strongly affected by the pinning strength, the vortex bundle size and the system size. Based on these results, we found crucial conditions to determine the validity of the Amontons-Coulomb's law, and proposed a criterion.