Induced order and re-entrant melting in classical two-dimensional binary clusters

Abstract

A binary system of classical charged particles interacting througha dipole repulsive potential and confined in a two-dimensionalhard-wall trap is studied by Brownian dynamics simulations. We found that the presence of smallparticles stabilizes the angular order of the system as aconsequence of radial fluctuations of the small particles. Thereis an optimum in the increased rigidity of the cluster as functionof the number of small particles. The small (i.e. defect)particles melt at a lower temperature compared to the bigparticles and exhibit a re-entrant behavior in its radialorder that is induced by the intershell rotation of the bigparticles.