Density Functional Theory of Laser-Induced Freezing in Colloidal Suspensions

Abstract

We reexamine the density functional theory of laser-induced freezing, i.e., the freezing of a colloidal liquid into crystalline order in the presence of an external periodic modulating potential ${V}_{e}$ with its wave vectors tuned to the ordering wave vector in the liquid phase. We show definitively that the initial first order freezing transition (at small ${V}_{e}$) changes to a continuous one (at large ${V}_{e}$) via a tricritical point provided the modulation wave vectors are suitably chosen. We also present predictions for the parameter values of the tricritical points for a realistic colloidal system.