SIMULATION OF STRESS-INDUCED ENHANCED DIELECTRIC PERMITTIVITY IN FERROELECTRIC SUPERLATTICE

A ferroelectric superlattice is composed of alternative stacks of two different ferroelectric materials. It has been demonstrated that enhanced dielectric permittivity occurs when the stacking periodicity is reduced down to a few monolayers. In this paper, this enhancement is numerically simulated by Landau-Khatalnikov theory. In-plane interfacial strain exists between adjacent stacks due to lattice mismatch, where the signs of the strain are different on the different sides of the interface. The dielectric enhancement for small periodicity, as observed from experiments, can be reproduced. Moreover, it is found that this enhancement increases with the number of periods. Both of these results reflect the relatively important influence of the in-plane interfacial strain. This is the first theoretical work to simulate the enhanced dielectric permittivity of ferroelectric superlattice.