Chevron layer structures in surface stabilized ferroelectric liquid crystal (SSFLC) cells filled with a material which exhibits the chiral nematic to smectic C^* phase transition

Abstract

Single component liquid crystals which exhibit the chiral nematic (N^*) to smectic C^* (SC^*) phase transition exhibit a large director tilt with respect to the local layer normal (typically 30 degrees or greater) in the SC^* phase which appears immediately upon cooling through the N^* - SC^* transition. In the SSFLC geometry and in the presence of an applied AC field these materials have been observed to align with their molecular long axes oriented along the buffing direction (for a buffed polymer alignment treatment) and with two domains of the smectic layers symmetrically disposed at a large angle (approximately the director tilt angle) with respect to the buffing direction^[1]. Furthermore, the layer domains are selectable with the application of a DC field applied normal to the bounding plates. We demonstrate, for the large tilt mixture SCE-10, that the layer domains in all cases adopt the chevron local layer structure^[2] immediately upon cooling through the transition. With decreasing temperature in the SC^* phase, the tilt of the layers with respect to the bounding plate normals (chevron tilt angle) is observed to monotonically increase as the interlayer spacing decreases. This lends further evidence that the mechanism for chevron formation is simply layer shrinkage.