Surface-mediated electroclinic effect in a chiral nematic liquid crystal

Optical phase-shift measurements are reported for a homeotropically aligned chiral nematic liquid crystal subject to an applied ac electric field E. A change in phase shift linear in E was observed, with a characteristic relaxation time {τ}{}0.01 s. The effect vanished for the nonchiral (racemic) version of the material. The data, taken together with the symmetry, are consistent with an electroclinic effect at the surface, such that the induced molecular tilt propagates elastically into the bulk.