Theory of longitudinal ferroelectric smectics

摘要: Recently, it was discovered that a-chiral smectic layers can undergo a phase transition into polar smectic. The new is fundamentally different from of the existing chiral Sm-C * ferroelectrics. In this paper we examine underlying mechanism responsible for form ferroelectricity. A Landau theory presented to discuss competition between ferroelectricity and other forms ordering such as anti-ferroelectricity. An effective free energy constructed describe coupling layer undulations polarizability sample. We find in Landau-Peierls instability absent second sound propagate along layers. Our considerations call number experiments which believe are crucial clarification true nature observed phases