Dielectric anomaly due to electrostatic coupling in ferroelectric-paraelectric bilayers and multilayers

A thermodynamic model is presented that describes the polarization and the dielectric response of ferroelectric-paraelectric bilayers and multilayers. It is shown that a strong electrostatic coupling between the layers results in the suppression of ferroelectricity at a critical paraelectric layer thickness. The bilayer is expected to have a gigantic dielectric response similar to the dielectric anomaly near Curie-Weiss temperature in homogeneous ferroelectrics at this critical thickness. A numerical analysis is carried out for a pseudomorphic (001) BaTiO3/SrTiO3 heteroepitaxial bilayer on (001) SrTiO3 and a stress-free BaTiO3/SrTiO3 bilayer. Complete polarization suppression and a dielectric peak are predicted to occur at approximately 66% and 14% of SrTiO3 in these two systems, respectively.