Six-layer periodic structures in antiferroelectric liquid crystals

Antiferroelectric liquid crystals (AFLCs) are materials which exhibit a number of smectic (Sm) tilted phases with various structures such as two (SmCA*), three (SmCFI1*), four (SmCFI2*) and six layers (SmC6d*). In this work, we use a discrete phenomenological model to study theoretically the prerequisites for the occurrence of six-layer structure. We find that if the quadrupolar coupling favoring uniplanar tilts in the neighboring layers is significant, a six-layer structure can appear below the SmC alpha* phase.