Dynamic scaling and freezing criteria in quasi-two-dimensional dispersions

We report on a Brownian dynamics simulation study of quasi-two-dimensional dispersions of colloidal spheres interacting by long-range electrostatic and dipolar magnetic forces. The calculated dynamic correlation functions are shown to obey dynamic scaling in terms of a characteristic relaxation time related to the mean particle distance and, due to hydrodynamic interactions, to the particle size. The dynamical freezing criterion of Löwen [Phys. Rev. E 53, R29 (1996)] is shown to be equivalent to a two-dimensional static freezing criterion.