Motile dislocations knead odd crystals into whorls

TL;DR

This paper demonstrates how transverse forces induced by rotation in colloidal systems generate self-propelled dislocations, transforming solids into dynamic, chiral whorl structures through a novel non-equilibrium mechanism.

Contribution

It introduces a new non-equilibrium phenomenon where transverse forces activate dislocations, leading to the formation of chaotic, self-kneading crystal whorls, supported by simulations and continuum theory.

Findings

Transverse forces induce self-propelled dislocations.

Dislocations lead to chaotic crystal whorl states.

Chiral instability causes dislocation proliferation.

Abstract

The competition between thermal fluctuations and potential forces is the foundation of our understanding of phase transitions and matter in equilibrium. Driving matter out of equilibrium allows for a new class of interactions which are neither attractive nor repulsive but transverse. The existence of such transverse forces immediately raises the question of how they interfere with basic principles of material self-organization. Despite a recent surge of interest, this question remains open. Here, we show that activating transverse forces by homogeneous rotation of colloidal units generically turns otherwise quiescent solids into a crystal whorl state dynamically shaped by self-propelled dislocations. Simulations of both a minimal model and a full hydrodynamics model establish the generic nature of the chaotic dynamics of these self-kneading polycrystals. Using a continuum theory, we explain how odd and Hall stresses conspire to destabilize chiral crystals from within. This chiral instability produces dislocations that are unbound by their self-propulsion. Their proliferation eventually leads to a crystalline whorl state out of reach of equilibrium matter.