The non-planar structure of Sm-C^* subphases and the free energy dependence on the azimuthal angle difference in adjacent layers

Abstract

The smectic subphases are observed between Sm-C^* and Sm-C_A^* in relatively narrow temperature ranges. The wave number q characterizes these phases such as Sm-C_A^* (3 layer structure, q=1/3) and Sm-C_A^* (4 layer structure, q=1/4). Sm-C_A^* (q=1/3) and Sm-C_A^* (q=1/4) have the non-planar structure recently clarified by Johnson et al. and Akizuki et al. To understand the non-planar structure of Sm-C_A^* (q=1/3) and Sm-C_A^* (q=1/4), we have studied the free energy terms that depend on the angle φ between two C-directors in adjacent layers. In addition, we have reconsidered whether the ANNNI model describes the emergence of subphases.