Melting of non reciprocal solids: how dislocations propel and fission in flowing crystals

TL;DR

This paper investigates how nonreciprocal interactions in driven soft matter systems influence the behavior of dislocations, leading to crystal melting through defect propulsion and fission, combining experiments, simulations, and theory.

Contribution

It demonstrates experimentally and theoretically that nonreciprocal forces cause dislocation motion and fission, resulting in the melting of driven crystals, a novel insight into nonreciprocal matter behavior.

Findings

Dislocations are propelled and fission in nonreciprocal driven crystals.

Dislocation dynamics reshape grain boundaries and induce melting.

Topological defects and nonreciprocal forces destabilize ordered phases.

Abstract

When soft matter is driven out of equilibrium its constituents interact via effective interactions that escape Newton's action-reaction principle. Prominent examples include the hydrodynamic interactions between colloidal particles driven in viscous fluids, phoretic interactions between chemically active colloids, and quorum sensing interactions in bacterial colonies. Despite a recent surge of interest in non-reciprocal physics a fundamental question remains : do non-reciprocal interactions alter or strengthen the ordered phases of matter driven out of equilibrium? Here, through a combination of experiments and simulations, we show how nonreciprocal forces propel and fission dislocations formed in hydrodynamically driven Wigner crystals. We explain how dislocation motility results in the continuous reshaping of grain-boundary networks, and how their fission reaction melts driven crystals from their interfaces. Beyond the specifics of hydrodynamics, we argue theoretically that topological defects and nonreciprocal interactions should invariably conspire to deform and ultimately destroy crystals whose the elementary units defy Newton's third law