Disordering Transitions and Peak Effect in Polydisperse Particle Systems

Abstract

We show numerically that in a binary system of Yukawa particles, a dispersity driven disordering transition occurs. In the presence of quenched disorder this disordering transition coincides with a marked increase in the depinning threshold, known as a peak effect. We find that the addition of poorly pinned particles can increase the overall pinning in the sample by increasing the amount of topological disorder present. If the quenched disorder is strong enough to create a significant amount of topological disorder in the monodisperse system, addition of a poorly pinned species generates further disorder but does not produce a peak in the depinning force. Our results indicate that for binary mixtures, optimal pinning occurs for topological defect fraction densities of 0.2 to 0.25. For defect densities below this range, the system retains orientational order. We determine the effect of the pinning density, strength, and radius on the depinning peak and find that the peak effect is more pronounced in weakly pinning systems.

8 pages, 8 postscript figures. Version to appear in PRE

References in corpus (5)

• Partial Clustering in Binary Two-Dimensional Colloidal Suspensions
• Experimental observation of structural crossover in binary mixtures of colloidal hard spheres
• Peak Effect versus Skating in High Temperature Nanofriction
• Charged inclusion in nematic liquid crystals
• Stripes, Clusters, and Nonequilibrium Ordering for Bidisperse Colloids with Repulsive Interactions