Scaling of the hysteresis loop in two-dimensional solidification

The first-order phase transitions between a two-dimensional (2d) gas and the 2d solid of the first monolayer have been studied for the noble gases Ar, Kr and Xe on a NaCl(100) surface in quasi-equilibrium with the three-dimensional (3d) gas phase. Using linear temperature ramps, we show that the widths of the hysteresis loops of these transitions as a function of the heating rate, r, scale with a power law rα, with α between 0.4 and 0.5 depending on the system. The hysteresis loops for different heating rates are similar. The island area of the condensed layer was found to grow initially with a t4 time dependence. These results are in agreement with theory, which predicts α = 0.5 and hysteresis loop similarity.