Interface effects in ferroelectric bilayers and heterostructures

We study the role of interlayer interfaces on the polarization response of ferroelectric-paraelectric bilayers using a nonlinear thermodynamic model. We carry out a numerical analysis for prototypical BaTiO3-SrTiO3 bilayers ranging from 40 to 800 nm total thickness as a function of SrTiO3 fraction. There exists a critical fraction of SrTiO3 at which the polarization is suppressed due to the depolarization field arising from the interlayer coupling and a large dielectric response is predicted. It is shown that this critical fraction decreases with decreasing total bilayer thickness, indicating that the interfacial effects are more pronounced in thinner bilayers. (c) 2007 American Institute of Physics.