Two-Step Melting in Two Dimensions: First-Order Liquid-Hexatic Transition
- Bernard, Etienne P. and Krauth, WernerPHYSICAL REVIEW LETTERS 107
Abstract : Melting in two spatial dimensions, as realized in thin films or at
interfaces, represents one of the most fascinating phase transitions in
nature, but it remains poorly understood. Even for the fundamental
hard-disk model, the melting mechanism has not been agreed upon after 50
years of studies. A recent Monte Carlo algorithm allows us to thermalize
systems large enough to access the thermodynamic regime. We show that
melting in hard disks proceeds in two steps with a liquid phase, a
hexatic phase, and a solid. The hexatic-solid transition is continuous
while, surprisingly, the liquid-hexatic transition is of first order.
This melting scenario solves one of the fundamental statistical-physics
models, which is at the root of a large body of theoretical,
computational, and experimental research.