Size effect on permittivity in ferroelectric polydomain thin films

The impact of electrode-adjacent passive layers on the small signal dielectric response of a ferroelectric film containing a 180degrees-domain pattern has been analyzed. It is shown that, for a realistic physical situation, the so-called "in-series capacitors formula" is still applicable for the description of the dielectric response of this system, however, with some apparent values of the passive-layer permittivity epsilon(mod), which is a function of parameters of the ferroelectric and the layers. It is also shown that the suppressive effect of the passive layer on the permittivity of the ferroelectric film can be significantly reduced when the permittivity of the ferroelectric is mainly controlled by the extrinsic (domain) contribution.