Effects of interfacial pseudo-spin coupling fluctuations on the dielectric properties of ferroelectric superlattices

Using effective-field theory with correlations, we investigate the effects of interfacial pseudo-spin coupling fluctuations on the susceptibility and polarization of ferroelectric superlattices within the framework of transverse Ising model. It is found that the interfacial coupling fluctuations increase the susceptibility in the low temperature region. For a strong interfacial coupling, the phase transition temperature decreases with the strength of fluctuations of the interfacial coupling. The dependence of the susceptibility on the superlattice period of BaTiO₃/SrTiO₃ are plotted for different interfacial coupling fluctuations strength. At room temperature, when the interfacial coupling fluctuation increases, the peak position of the susceptibility will shift to a large superlattice period.