Formation and structure of a soliton in an antiferroelectric liquid crystal in an electric field

The soliton structure in an antiferroelectric liquid crystal in an electric field is calculated in the discrete phenomenological Landau model for phase transitions. The anticlinic structure of the antiferroelectric crystal gives rise to nontrivial features of the soliton structure and the stability of the soliton. The soliton is topologically stable in a metastable state if the electric field is much higher than the field of antiferroelectric-helix unwinding. A structural transition with a step-like change in the orientation of molecules occurs as the soliton field varies. A peculiar soliton (synclinic pair) can be formed if the barrier between the anti- and ferroelectric structures is large. The calculation shows the possibility of a large electroclinic effect in the soliton, i.e., a variation in the molecular tilt angle in an electric field in the vicinity of the transition of the structure to the synclinic state.