Effect of temperature and velocity on superlubricity

TL;DR

This paper investigates how temperature and sliding velocity influence superlubricity using numerical simulations of the Frenkel-Kontorova model, revealing resonant phonon excitations and a velocity-dependent effective friction.

Contribution

It introduces a detailed analysis of temperature and velocity effects on superlubricity, highlighting the emergence of a velocity-dependent damping coefficient from microscopic dynamics.

Findings

Resonant phonon excitations induce effective friction.

Damping coefficient peaks at resonant velocities and increases with temperature.

Superlubricity persists at low velocities with finite damping.

Abstract

We study the effects of temperature and sliding velocity on superlubricity in numerical simulations of the Frenkel-Kontorova model. We show that resonant excitations of the phonons in an incommensurate sliding body lead to an effective friction and to thermal equilibrium with energy distributed over the internal degrees of freedom. For finite temperature, the effective friction can be described well by a viscous damping force, with a damping coefficient that emerges naturally from the microscopic dynamics. This damping coefficient is a non-monotonic function of the sliding velocity which peaks around resonant velocities and increases with temperature. At low velocities, it remains finite and nonzero, indicating the preservation of superlubricity in the zero-velocity limit. Finally, we propose experimental systems in which our results could be verified.