NATURE OF THE BLUE-PHASE-III-ISOTROPIC CRITICAL-POINT - AN ANALOGY WITH THE LIQUID-GAS TRANSITION

The analogy with the liquid-gas critical point is analyzed to clarify the nature of the pretransitional behavior of physical properties in t he vicinity of the Blue-Phase-m-isotropic transition in chiral liquid crystalline systems. The analogy is unusual: temperature serves as the ordering field and entropy plays the role of the order parameter. Bot h mean field and parametric equations of state are formulated in terms of scaling fields. The scaling fields are linear combinations of the physical fields, which are temperature and chirality. It is shown that mixing of the physical field variables naturally leads to a strong as ymmetry with respect to the transition temperature in the behavior of the physical properties that cannot be described by simple power laws. While the mean field theory gives a good description of the experimen tal data, the scaling theory, if one incorporates mixing of the field variables, gives even better agreement with the experimental data, pla cing this transition in the same universality class as the three-dimen sional Ising model.