Power law load dependence of atomic friction

TL;DR

This paper presents a theoretical analysis of atomic-scale friction, revealing a power law relationship between load and both friction force and interaction potential amplitude, highlighting differences from macroscopic contact behavior.

Contribution

It introduces a theoretical model showing a power law load dependence of atomic friction and potential amplitude, emphasizing the behavior of sharp undeformable tips.

Findings

Friction force scales with load with an exponent of approximately 1.6.

Interaction potential amplitude also follows a power law with load.

Results contrast atomic-scale tips with macroscopic elastic contacts.

Abstract

We present a theoretical study of the dynamics of a tip scanning a graphite surface as a function of the applied load. From the analysis of the lateral forces, we extract the friction force and the corrugation of the effective tip-surface interaction potential. We find both the friction force and potential amplitude to have a power law dependence on applied load with exponent $\sim 1.6$. We interpret these results as characteristic of sharp undeformable tips in contrast to the case of macroscopic and elastic microscopic contacts.