Plasticity in a Smectic-ALiquid Crystal

Abstract

We present direct measurements of the layer rigidity in a smectic-$A$ liquid crystal, 4′-$n$-octyloxy-4-cyanobiphenyl. For low normal to the layers, the instantaneous induced stress is elastic and gives $B=0.8\mathrm{}\times {10}^7$ cgs units at 60°C. In response to a steplike strain, the stress relaxes almost completely, with a time constant ∼50 ms. The relaxation stops for a residual strain smaller than ½ layer over the total thickness of the smectic sample.