Theoretical Aspects of Phase Transitions in Ferroelectric Thin Films

Abstract

Phase transitions in ferroelectric thin films are discussed theoretically on the basis of the Tilley–Zeks model for the case where the transition is of the second order. A surface is characterized by an extrapolation length δ, which is a key concept of the model. For a positive δ the ferroelectric phase transition tends to be suppressed, with a decreasing transition temperature, while for a negative δ ferroelectricity tends to be enhanced, with an increasing transition temperature. Not only symmetric-surface cases, but also asymmetric-surface cases are discussed.