Critical fluctuations near the smectic-hexatic phase transition with anticlinic structure.

Layer compression modulus B measurements have been conducted near the transitions between smectic and hexatic phases with synclinic and anticlinic structures. In the synclinic structure, B shows no pretransitional softening near the phase transition. However, in the anticlinic structure, we observed evident critical softening of B near the smectic-hexatic phase transition. These results clearly reveal that the introduction of the in-plane hexatic order in the anticlinic structure is different from the usual smectic-hexatic phase transition.