Active topological strings in renewing nematopolar fluids

TL;DR

This paper investigates how continuous material renewal stabilizes topological defect structures called strings in active nematopolar fluids, revealing mechanisms of stabilization and active chaos, with implications for biological systems.

Contribution

It introduces the concept that material renewal stabilizes topological defect strings in active matter with mixed order parameters, a novel insight in the field.

Findings

Stable topological strings are found in renewing nematopolar fluids.

Active stress induces active-string chaos.

Material renewal is a generic mechanism for defect stabilization.

Abstract

Active matter often simultaneously exhibits different kinds of orientational order and, in many cases of biological interest, undergoes continuous material renewal. In renewing nematopolar fluids we find stable topological strings, structures consisting of two nematic point defects connected by a defect line in the polar field. We identify the mechanism underlying string stabilization and unveil how string length is determined. In the presence of active stress, we observe active-string chaos. Our work identifies continuous material renewal as a generic mechanism underlying the stabilization of topological defect structures in systems with mixed order parameters. It could be used for orchestrating living matter during development and other biological processes.