Sliding Over a Phase Transition

TL;DR

This paper models how structural phase transitions influence nanoscale sliding friction, revealing nonmonotonic behavior around the critical temperature and potential for friction control using phase transition properties.

Contribution

It introduces a simulation-based analysis of phase transition effects on friction, highlighting the role of order parameter fluctuations and their impact on stick-slip behavior.

Findings

Friction peaks at the critical temperature Tc.

Order parameter flips increase near Tc, affecting friction.

Friction can be modulated by controlling phase transition states.

Abstract

The effects of a displacive structural phase transition on sliding friction are in principle accessible to nanoscale tools such as the Atomic Force Microscopy, yet they are still surprisingly unexplored. We present model simulations demonstrating and clarifying the mechanism and potential impact of these effects. A structural order parameter inside the material will yield a contribution to stick-slip friction that is nonmonotonic as temperature crosses the phase transition, peaking at the critical Tc where critical fluctuations are strongest, and the sliding-induced order parameter local flips from one value to another more numerous. Accordingly, the friction below Tc is larger when the order parameter orientation is such that flips are more effectively triggered by the slider. The observability of these effects and their use for friction control are discussed, for future application to sliding on the surface of and ferro- or antiferro-distortive materials.