Static Friction as a Function of Waiting Time Probed by Dynamics of Driven Vortices in La2-xSrxCuO4 Thin Films

TL;DR

This study explores how static friction in high-temperature superconductor vortices depends on waiting time, revealing the influence of pinning strength, vortex bundle size, and system size on frictional relaxation.

Contribution

It introduces a detailed analysis of waiting-time dependent static friction in vortex systems, proposing a criterion for the applicability of Amontons-Coulomb's law in such contexts.

Findings

F_s(t_w) varies across the B-T phase diagram and sample types.

Thermal fluctuation relaxation is affected by pinning and system parameters.

A criterion for the validity of classical friction laws is proposed.

Abstract

We investigated the dynamics of driven vortices in high-$T_c$ superconductor as an ideal model system to study the physics of friction. The waiting-time dependence of the maximum static friction force, $F_s(t_w)$, was measured in La$_{2-x}$Sr$_x$CuO$_4$ thin films with different structures, sample sizes and pinning force. We found various kinds of $F_s(t_w)$ in the $B$-$T$ phase diagram and in different types of samples. The results suggest that the relaxation 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.