Defect interactions in two-dimensional colloidal crystals: vacancy and interstitial strings

We study the effective interactions of interstitials and vacancies in two-dimensional colloidal crystals with Monte Carlo simulations. For both types of defects, the interactions are strongly attractive leading to the formation of defect strings. These highly mobile strings, two-dimensional analogs of prismatic dislocation loops observed in irradiated metals, arise from forces mediated by the lattice that cannot be reduced to effective pair interactions between defects.