Improvement of ferroelectric and dielectric properties in BaTiO3/LaNiO3 superlattices by regulating the ferroelectric layer thickness

Abstract

Ferroelectric superlattices exhibit rich functional characteristics. Yet, the ferroelectric properties are always unsatisfactory due to the presence of depolarization field resulting from the polarization discontinuities between the component materials, which has become a bottleneck problem hindering the improvement of ferroelectric properties and further industrial applications. Here, the BTO/LNO superlattices composed of ferroelectric (BaTiO3, BTO) and metallic (LaNiO3, LNO) materials were prepared by pulsed laser deposition (PLD). The periodic thickness of the LNO layers was fixed to 2 unit cells, while the periodic thickness of the BTO layers was changed. We demonstrate experimentally that by regulating the BTO periodic thickness, BTO/LNO superlattices exhibit excellent and adjustable ferroelectric and dielectric properties. The enhancement of electrical properties is closely related to the increase of tetragonality (c/a) combined with the effect of the ultra-thin LNO layers and the accumulation of oxygen vacancies at superlattice interfaces on reducing the depolarization field. We hope this work will provide an effective strategy for optimizing the ferroelectric properties of ferroelectric superlattices based on the component material and periodic structure regulation.