On anomalous influence of an external electric field on a second-order transition in a thin ferroelectric film

The specific features of a phase transition in a thin ferroelectric film in an external electric film have been studied in terms of the Landau–Ginzburg–Devonshire phenomenological theory in the dependence on the film thickness and the type of polarization pinning on its surface. The phase transition mechanism is found to be changed in an electric field. The phase transition shifts in temperature, along with a specific smearing that differs from the smearing in a bulk material in the appearance of a temperature range near TC with an anomalously high dielectric susceptibility; in this case, the shift is dependent on the film thickness, the properties of its surface and it is independent of the field strength in weak fields.