Effects of thermal rippling on the frictional properties of free-standing graphene

TL;DR

This study investigates how thermally excited ripples in free-standing graphene influence its frictional behavior, revealing complex temperature-dependent effects that depend on experimental conditions.

Contribution

It demonstrates that thermal ripples cause non-monotonic changes in graphene's friction, highlighting a unique temperature-dependent dynamic roughness in atomically thin membranes.

Findings

Friction varies non-monotonically with temperature.

Sample size and tip parameters affect frictional response.

Thermally excited ripples influence nanoscale friction behavior.

Abstract

With use of simulated friction force microscopy, we study the effect of varying temperature on the frictional properties of suspended graphene. In contrast with the theory of thermally activated friction on the surfaces of three-dimensional materials, kinetic friction is demonstrated to both locally increase and decrease with increasing temperature, depending on sample size, scanning tip diameter, scanning rate, and the externally applied normal load. We attribute the observed effects to the thermally excited flexural ripples intrinsically present in graphene, demonstrating a unique case of temperature-dependent dynamic roughness in atomically thin membranes.