PHASE-DIAGRAM OF CHOLESTERIC LIQUID-CRYSTALS IN A FIELD

The phase diagram of a bull; cholesteric liquid crystal in an electric or magnetic field applied perpendicular to the pitch axis is studied. This is an example of a system which exhibits different types of phas e transitions between various modulated and homogeneous states. Possib le transitions are of three types: (1) first order, (2) continuous and described as a condensation of solitons with repulsive interaction, o r (3) continuous but characterized by a small order parameter. The det ailed behavior of the temperature-field phase diagram is found to be s trongly dependent on the intrinsic chirality, where the existence of a n undulating state is predicted at high chirality. The relevant temper ature, electric field, and chirality ranges are experimentally attaina ble.