Prof. Dr. Rene Messina from University of Lorraine, France visited SCL and gave a seminar on "Crystallization of binary mixtures in two dimensions"

Abstract:

Two-dimensional crystallization can be experimentally realized for magnetic particles confined at the air-water interface under a strong external magnetic field. In the first part of the seminar, I will summarize recent progress achieved in the understanding of freezing for two dimensional dipolar mixtures. Equilibrium and non-equilibrium aspects are discussed.
Results concerning the crystallization of ionic mixtures in two- dimensions will be presented as well. Upon varying the size ratio, the stable two-dimensional crystalline lattices consist of square, triangular and rhombic crystals as well as a ion pair gas and a gas of one-dimensional crystalline chains. Thereby, we confirm the square structure, found experimentally on charged granulates, and predict new phases detectable in experiments on granular and colloidal matter.
Results concerning the crystallization of ionic mixtures in two- dimensions will be presented as well. Upon varying the size ratio, the stable two-dimensional crystalline lattices consist of square, triangular and rhombic crystals as well as a ion pair gas and a gas of one-dimensional crystalline chains. Thereby, we confirm the square structure, found experimentally on charged granulates, and predict new phases detectable in experiments on granular and colloidal matter.

It is well known from solid state studies that strongly confined (i.e., quasi two-dimensional or even one-dimensional) systems exhibit properties and a phase behavior that may drastically differ from those in the bulk. Such features are also vivid in colloidal systems, and those materials represent ideal model systems to analyze (experimentally as well as theoretically) and understand confinement effects on the mesoscopic scale corresponding to the inter-particle distance. Whereas one-component strongly repulsive colloidal particles lead to a triangular lattice, the binary mixture counterpart provides a very rich phase behavior.