Dumbbell impurities in 2D crystals of repulsive colloidal spheres induce particle-bound dislocations

TL;DR

This study investigates how anisotropic dumbbell-shaped impurities influence defect formation and dynamics in 2D colloidal crystals, revealing a transition from local distortion to dislocation binding as dumbbell length varies.

Contribution

It demonstrates the role of dumbbell impurities in inducing and controlling dislocations in 2D colloidal crystals, a novel insight into impurity effects with anisotropic shapes.

Findings

Dumbbell length controls transition from distortion to dislocation binding.

Dumbbells can move within the hexagonal lattice.

Impurities influence material properties via particle-bound dislocations.

Abstract

Impurity-induced defects play a crucial role for the properties of crystals, but little is known about impurities with anisotropic shape. Here, we study how colloidal dumbbells distort and interact with a hexagonal crystal of charged colloidal spheres at a fluid interface. We find that subtle changes in the dumbbell length induce a transition from a local distortion to a particle-bound dislocation, and determine how the dumbbell moves inside the repulsive hexagonal lattice. Our results provide new routes towards controlling material properties through particle-bound dislocations.