Patrick Dillmann, Georg Maret, Peter Keim
A two-dimensional monolayer of monodisperse colloids is quenched rapidly below the melting temperature into the crystalline phase and the nature of the transition is investigated. Analyzing the local order as function of time we find shortly after the quench a bimodal distribution of highly ordered (crystalline) and fluidlike particles, indicating that the KTHNY-scenario known from 2D equilibrium transitions does not hold. Critical nucleation theory can not describe the solidification scenario found in our experiment, either, as we do not find a lag time nor a critical nucleus size. The average size of nuclei grows monotonically as expected, but surprisingly, comparing the size of an individual 'nucleus' in consecutive timesteps, shrinking is always more probable than growing. This indicates a strongly asymmetric nucleation behaviour. Nevertheless, the averaged dynamics of the degree of crystallinity is found to be in very good agreement with the heuristic Johnson-Mehl-Avrami-Kolmogorov (JMAK)-scenario.
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http://arxiv.org/abs/1303.6821
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