Nature of a Nematic-Smectic-A-Smectic-CMulticritical Point

Recent x-ray data on the angles and 2-theta shifts in the smectic-$C$ phase of a binary liquid-crystal mixture were analyzed via a mean-field theory. We demonstrated that the smectic-$A$-smectic-$C$ transitions ($\mathrm{AC}$) are mean-field-like. This conclusion is consistent with recent heat-capacity data along the $\mathrm{AC}$ transition line. Furthermore, the nematic-smectic-$A$-smectic-$C$ point in this binary mixture is found to be in the vicinity of the tricritical point along the $\mathrm{AC}$ and nematic-smectic-$C$ transition line.