Interferometric measurements at a smectic-A—smectic-C-phase transition

Abstract

We report measurements of the tilt angle $\psi$ near the second-order $\mathrm{Sm}A-\mathrm{S}\mathrm{m}C$ transition in azoxy-4,4′-di-undecyl-$\alpha$-methylcinnamate. Data analysis shows that this transition, which belongs to the same universality class as ${}_{}{}^4{}_{}{}^{}\mathrm{He}$, has, in the absence of a constraining field, a critical exponent $\beta =0.36\mathrm{}\pm 0.005$.