Molecular theoretic study of Freedericksz transition. Symmetry breaking of oblique axial order

Abstract

AbstractFreedericksz transition, which is usually analyzed by an elastic theory, is studied on the basis of statistical mechanical ground, where nematics with positive dielectric anisotropy in homogeneous anchoring cell is exposed to an electric field in the direction of wall normal. In low temperature region, an oblique axial symmetry breaking occurs, which is nothing but the Freedericksz transition. In high temperature and high field region, biaxial nematic phase with principal axis parallel to the field direction at interior area of the system is proved to appear. A phase diagram on the field versus temperature plane is obtained and compared with the one at a bulk with common biaxial symmetry, where both of electric and magnetic fields are applied in directions perpendicular to each other. In the latter, no symmetry breaking occurs, in contrast with the former case above-mentioned, and the reason why this difference occurs is elucidated.