Dielectric nonlinearities in ferroelectric thin-film heterostructures

The influence of the film-electrode interface on the ac-electric field depe ndence of the dielectric permittivity in ferroelectric thin-film heterostru ctures has been studied. The dielectric nonlinearities in epitaxial thin-fi lm heterostructures of ferroelectric PbZr0.65Ti0.35O3 and relaxor ferroelec tric (PbMg1/3Nb2/3O3)(0.68)-(PbTiO3)(0.32) were measured at subswitching fi elds. A dramatic difference between the dielectric nonlinearities possessed by ferroelectric films and those exhibited by the corresponding heterostru ctures was revealed both by model evaluations and experimental observations . In the heterostructures, due to the presence of an interface layer the di electric nonlinearities can be considerably suppressed and their type can b e changed compared to those in the films. (C) 2001 American Institute of Ph ysics.