Relaxation process of magnetic friction under sudden changes in velocity

TL;DR

This study investigates the relaxation behavior of magnetic friction in a chain-lattice Ising spin system after sudden velocity changes, revealing a two-phase relaxation process involving a rapid change and slow magnetic relaxation.

Contribution

It introduces a dynamic model of magnetic friction with a sudden velocity change and identifies a two-stage relaxation process, highlighting differences from traditional solid surface behavior.

Findings

Relaxation of frictional force occurs in two stages: sudden change and slow relaxation.

Slow relaxation is driven by magnetic structure relaxation in the model.

Similar two-phase relaxation observed on real solid surfaces, but caused by different mechanisms.

Abstract

Although there have been many studies of statistical mechanical models of magnetic friction, most of these have focused on the behavior in the steady state. In this study, we prepare a system composed of a chain and a lattice of Ising spins that interact with each other, and investigate the relaxation of the system when the relative velocity $v$ changes suddenly. The situation where $v$ is given is realized by attaching the chain to a spring, the other end of which moves with a constant velocity $v$. Numerical simulation finds that, when the spring constant has a moderate value, the relaxation of the frictional force is divided into two processes, which are a sudden change and a slow relaxation. This behavior is also observed on regular solid surfaces, although caused by different factors than our model. More specifically, the slow relaxation process is caused by relaxation of the magnetic structure in our model, but is caused by creep deformation in regular solid surfaces.