Reentrant melting of two-dimensional colloidal systems

When a two-dimensional colloidal suspension of highly charged particles is subjected to a periodic one-dimensional (1D) light field, a liquid-solid tr ansition can be induced. This phase transition is well known as light-induc ed freezing. However, upon further increase of the intensity, the crystal i s found to remelt (laser-induced melting) to a 1D liquid. This reentrance b ehaviour is in good agreement with predictions based on Monte Carlo simulat ions. We suggest explaining this intriguing phenomenon in terms of particle fluctuations which tend to stabilize the crystalline phase.