Schematic Models for Active Nonlinear Microrheology

TL;DR

This paper investigates the nonlinear behavior of dense colloidal suspensions under active microrheology using a schematic mode-coupling model, simulations, and experimental data to understand the microscopic friction response.

Contribution

It introduces a schematic mode-coupling theory model to describe nonlinear microrheology and compares it with simulations and experimental results.

Findings

Identification of a delocalization transition in the microscopic friction coefficient.

Agreement between model predictions, simulations, and experimental data at various forces.

Insights into the behavior of colloidal suspensions at very large applied forces.

Abstract

We analyze the nonlinear active microrheology of dense colloidal suspensions using a schematic model of mode-coupling theory. The model describes the strongly nonlinear behavior of the microscopic friction coefficient as a function of applied external force in terms of a delocalization transition. To probe this regime, we have performed Brownian dynamics simulations of a system of quasi-hard spheres. We also analyze experimental data on hard-sphere-like colloidal suspensions [Habdas et al., Europhys. Lett., 2004, 67, 477]. The behavior at very large forces is addressed specifically.