Electrically induced undulations and their competition with electrically induced convection in cholesteric liquid crystals.

Abstract

We show that cholesteric liquid crystals with a sufficiently short pitch, when put in an electric field, can exhibit undulations, the analog of mechanical undulations or of thermal undulations obtained when an external pressure or a temperature gradient is applied, respectively. As the pitch is increased a competition between the electric-field-induced undulations and the electrohydrodynamic instability arises. We give numerical estimates for both instabilities in this system, which represents another example of a competition between a constrained pattern-forming equilibrium system (electric-field-induced undulations) and a nonequilibrium (electrohydrodynamic) instability.