Spiral layer undulation defects in B7 liquid crystals

Abstract

In bent-core smectic liquid crystal phases, a strong local preference for layering coupled to the bent molecular shape gives rise to two spontaneous symmetry-breaking instabilities, polar orientational ordering of the molecules and molecular tilt, which combine to produce chiral phases. The B7 is one such phase characterized by layer undulations associated with the formation of periodic, polarization-modulation stripes that can be visualized using FFTEM. By analyzing topological defects in the B7 layer undulation texture, we can determine the molecular organization within the layers which indicates that the layers are homochiral. The layer undulations coupled with the layer chirality forms clockwise or anticlockwise spiral patterns as they nucleate and grow.