Critical fluctuations at the untilted-tilted phase transition in chiral smectic liquid crystals

摘要

The layer compression modulus B was measured near the Sm-A-Sm-C* and Sm-A-Sm-C-A* transitions of chiral smectic liquid crystals. B shows a marked pretransitional softening due to the order parameter fluctuations above the phase transition. The width of the critical region of the Sm-A-Sm-C* and Sm-A-Sm-C-A* transitions is smaller than that of the Sm-A-Sm-C-alpha* transition. The critical exponents of B are in agreement with the theoretical description based on renormalization-group method. These results reveal that these transitions are not of the Landau mean-field type. [References: 26]