Influence of external electric field on phase transitions in the thin film ferroelectrics

Based on the phenomenological theory of Landau-Ginzburg-Devonshire, the singularities of the phase transition in a thin ferroelectric film in external electric field are investigated depending on the film thickness and the type of polarization fixed on its planes. It was found that in electric field the phase transition shifts in temperature, and the shift value depends on the film thickness and the properties of its planes. In the linear approximation at the weak fields, the temperature shift of phase transition does not depend on the field strength until a certain definite value. For ferroelectric triglycine sulfate film with the thickness 35 nm, this value is 116 V/cm.