Unique Pitch Evolution in the Smectic-C^* _alpha Phase

Employing resonant x-ray diffraction, we observed unique pitch evolutions in the smectic-C phase in mixtures of two antiferroelectric liquid crystals. Our results show that the pitch in this phase continuously evolves across 4 layers, contradicting a theoretical model that predicts that the smectic-CFI2 phase intervenes in the smectic-C phase. The phase sequences we found can be explained by another model that includes one type of long-range interaction among smectic layers