Density-induced reentrant melting of colloidal Wigner crystals

TL;DR

This paper investigates the phenomenon of reentrant melting in colloidal Wigner crystals, revealing that surface chemistry and ion adsorption competition are key factors in this density-dependent phase transition.

Contribution

It introduces a theoretical framework connecting colloid-ion interactions to reentrant melting, explaining experimental observations through surface chemistry effects.

Findings

Reentrant melting occurs with increasing colloid density.

Surface chemistry involving ion adsorption influences phase behavior.

Theoretical models align with experimental data.

Abstract

Electrostatic repulsions can drive crystallization in many-particle systems. For charged colloidal systems, the phase boundaries as well as crystal structure are highly tunable by experimental parameters such as salt concentration and pH. By using projections of the colloid-ion mixture to a system of (soft) repulsive spheres and the one-component plasma (OCP), we study the hitherto unexplained experimentally observed reentrant melting of electrostatically repelling colloids upon increasing the colloid density. Our study shows that the surface chemistry should involve a competition between adsorption of cations and anions to explain the observed density-induced reentrant melting.