Discovery of a novel smectic-c* liquid-crystal phase with six-layer periodicity

We report the discovery of a new smectic-C* liquid-crystal phase with six-layer periodicity by resonant x-ray diffraction. Upon cooling, the new phase appears between the SmCα* phase having a helical structure and the SmCd4* phase with four-layer periodicity. This SmCd6* phase was identified in two mixtures which have an unusual reversed SmCd4*- SmC* phase sequence. The SmCd6* phase shows a distorted clock structure. Three theoretical models have predicted the existence of a six-layer phase. However, our experimental findings are not consistent with the theories.