Phase Transitions in Thin Films

Abstract

After a brief review of the experimental data concerning phase transitions in ferroelectric thin films, a theoretical treatment based on the Landau-Devonshire expansion is presented. A surface is characterised by a length δ, the negative of the logarithmic derivative of the order parameter at the surface. For negative δ, the critical temperature Tc of a film is increased above the bulk value, while for positive δ it is decreased. A careful discussion of depolarisation effects is presented. It is shown that these reduce Tc below the value found if depolarisation is neglected. Various possible extensions of the theory are pointed out.KeywordsPhase TransitionCritical TemperatureLandau TheoryFerroelectric Phase TransitionFerroelectric Thin FilmThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.