Specific Heat near the Nematic-Smectic-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>A</mml:mi></mml:math>Tricritical Point

Abstract

Specific-heat measurements near the nematic-smectic-$A$ transitions of the octyloxy, nonyloxy, and decyloxy members of the 4-$n$-pentyl-phenylthiol-4\ensuremath{'}-alkoxybenzoate ($\overline{n}\mathrm{S}5$) homologous series reveal the presence of critical-tricritical crossover behavior upon increasing $\overline{n}$, with ${\overline{n}}_{t}\ensuremath{\sim}\overline{9}$. The results are consistent with Alben's extension of de Gennes's superfluid analogy to include superfluid-${\mathrm{He}}^{3}$-${\mathrm{He}}^{4}$-like tricritical behavior.