Active Rheology in Odd Viscosity Systems

TL;DR

This paper investigates how odd viscosity influences active rheology, revealing novel effects like velocity boosts and Hall angles in driven probe particles, with implications for systems like skyrmions.

Contribution

It demonstrates how odd viscosity causes unique probe particle dynamics, including velocity boosts and Hall angles, in active rheology without quenched disorder.

Findings

Probe particle velocity can increase with density due to the Magnus effect.

Odd viscosity imparts a Hall angle to the probe particle.

Velocity boost and Hall angle depend strongly on the drive strength.

Abstract

Odd viscosity arises in systems with time reversal symmetry breaking, which creates non-dissipative effects. One method to probe changes in viscosity is to examine the dynamics of a single probe particle driven though a medium, a technique known as active rheology. We show that active rheology in a system with odd viscosity and no quenched disorder reveals a variety of novel effects, including a speed up of the probe particle with increasing system density when the background medium creates a velocity boost of the driven particle due to the Magnus effect. In contrast, the probe particle velocity in the dissipation-dominated limit monotonically decreases with increasing system density. We also show that the odd viscosity imparts a Hall angle to the probe particle, and that both the Hall angle and the velocity boost depend strongly on the drive. These results should be general to other systems with odd viscosity, including skyrmions in chiral magnets.