Static and dynamic friction in sliding colloidal monolayers

TL;DR

This paper combines simulations and theory to explore static and dynamic friction in colloidal monolayers sliding over periodic potentials, highlighting their potential for nanotribology research.

Contribution

It provides the first theoretical demonstration of colloid sliding's impact on nanotribology, reproducing experimental features and analyzing frictional behavior.

Findings

Contrast between soliton motion and pair nucleation at static friction threshold

Friction depends on speed, potential amplitude, and lattice mismatch

Colloid sliding offers a new platform for nanotribology studies

Abstract

In a pioneer experiment, Bohlein et al. realized the controlled sliding of two-dimensional colloidal crystals over laser-generated periodic or quasi-periodic potentials. Here we present realistic simulations and arguments which besides reproducing the main experimentally observed features, give a first theoretical demonstration of the potential impact of colloid sliding in nanotribology. The free motion of solitons and antisolitons in the sliding of hard incommensurate crystals is contrasted with the soliton-antisoliton pair nucleation at the large static friction threshold Fs when the two lattices are commensurate and pinned. The frictional work directly extracted from particles' velocities can be analysed as a function of classic tribological parameters, including speed, spacing and amplitude of the periodic potential (representing respectively the mismatch of the sliding interface, and the corrugation, or "load"). These and other features suggestive of further experiments and insights promote colloid sliding to a novel friction study instrument.