Mean-Field to Tricritical Crossover Behavior near the $\mathrm{Smectic}-A-\mathrm{Smectic}-C^{*}$ Tricritical Point

Precise x-ray measurements of the tilt angle near the $\mathrm{Smectic}-A-\mathrm{Smectic}-C^{*}$ tricritical point show clear evidence of mean-field to tricritical crossover behavior; the mean-field region shrinks to zero at the tricritical point.