Figure 4
From: Exploring structural phase transitions of ion crystals

Power-law scalings of 6–16 ions with the measured and simulated values of the critical anisotropic parameters versus the ion number N, where the curves are plotted based on the calculation by and the experimental data are averaged over the measured data around the critical points of the phase transitions.
The lower (upper) curve is for the first (second) phase transition plotted in Fig. 3(b). The error bars of the experimental data are determined by the mean square root, as explained in the text.