Ferroelectric self-field effect: Implications for size effect and memory device

Ideal ferroelectrics have mostly been modeled as insulators, i.e., infinite band gap materials, having a spontaneous polarization. Based on this assum ption, theories for the finite size effect, the domain configuration, and t he depolarization field instability have been proposed. However, most of ox ide perovskite ferroelectrics have finite band gaps of 3 to 4 eV. We show t hat the inclusion of the finite band gap effect changes drastically convent ional understanding of the finite size effect and others. The conclusions e xtracted from the present approach are consistent with recent experimental results. In particular. we discuss the stability of ferroelectric memory de vices in detail.