Defect dynamics in active smectics induced by confining geometry and topology

TL;DR

This paper investigates how confinement geometry and topology influence defect dynamics in active smectic layers, revealing complex behaviors and controllable transitions driven by boundary shapes using an active phase field crystal model.

Contribution

It introduces a comprehensive study of defect dynamics in active smectics under various confining geometries and topologies, highlighting new dynamical states and control mechanisms.

Findings

Perpetual creation-annihilation defect states at intermediate activity.

Boundary cusps govern transition from oscillatory to damped defect dynamics.

Complex defect patterns depend on confining shape and topology.

Abstract

The persistent dynamics in systems out of equilibrium, particularly those characterized by annihilation and creation of topological defects, is known to involve complicated spatiotemporal processes and is deemed difficult to control. Here the complex dynamics of defects in active smectic layers exposed to strong confinements is explored, through self-propulsion of active particles and a variety of confining geometries with different topology, ranging from circular, flower-shaped epicycloid, to hypocycloid cavities, channels, and rings. We identify a wealth of dynamical behaviors during the evolution of complex spatiotemporal defect patterns as induced by the confining shape and topology, particularly a perpetual creation-annihilation dynamical state at intermediate activity with large fluctuations of topological defects and a controllable transition from oscillatory to damped time correlation of defect number density via mechanisms governed by boundary cusps. Our results are obtained by using an active phase field crystal approach. Possible experimental realizations are also discussed.