Domain structures in ferroelectric liquid crystals

Domain structures called steric (or striped) domains are investigated in ferroelectric liquid crystals (FLCs). The domain lines are aligned perpendicular to the smectic layers with a period proportional to the FLC cell thickness L. Neither FLC polarization nor helix pitch affects the domain pattern. Striped domains disappear in thick cells (L > 8–10 μm) and transform to a new type of surface domain without any preferred orientation in thin samples (L < 1·0 μm). The existence and structure of the steric domains define properties such as contrast and bistability of the FLC cell. We propose a qualitative explanation of this domain pattern and compare its characteristics with ferroelectric domains discovered earlier by Beresnev et al. in FLCs.