Electric-field-induced chiral separation in liquid crystals.

Recently it was shown that smectic liquid crystal phases formed by achiral banana-shaped molecules are chiral. Films of such phases generally contain both homochiral (consisting of layers of the same chirality) and racemic (the chirality alternates in subsequent layers) domains. So far it has not been clear how to control the overall chirality of the sample. By observing the effects of the application of suitable electric fields, it was noted that chirality of a film of banana shaped molecules was interchanged between homochiral and racemic. We present dielectric, electro-optic, and polarization current measurements on both the racemic and chiral states. The observations indicate that the synclinic states have minimum free energies. The observed dielectric modes can be explained by a simple model assuming that the antiferroelectric state is very weak.