Artificially induced ferroelectric-like behavior in an antiferroelectric sandwich structure by interface engineering

Abstract

Interface engineering is essential for achieving fascinating interfacial functionalities in a single all-oxide-interface-based device. In the present work, a sandwich structure (Pb0.94La0.06(Zr0.95Ti0.05)O3 (PLZT)/HfO2/ Pb0.94La0.06(Zr0.95Ti0.05)O3) was fabricated via a chemical solution approach. A distinct “ferroelectricity-like” behavior with high Pmax (∼ 80 μC/cm2) and Pr (∼ 36 μC/cm2) is demonstrated. The dielectric HfO2 thin layer presents a tetragonal symmetry structure, which stabilizes a slight distorted structure of the upper PLZT layer (PLZT(T)) with a= 4.19(9) Å, b= 4.10(6) Å, β ∼ 91.04˚. In PLZT(T), the ferroelectric (FE) phase is identified as the matrix embedded with a small amount of AFE nanodomains, while the bottom PLZT layer (PLZT(B)) exhibits typical AFE incommensurately modulated structures. The near-interface structures in both PLZT layers are characterized by ferroelectric polarizations with head-to-tail configuration across the heterointerface. Such discontinuous, downward polarizations support the accumulation of oxygen vacancies at the heterointerface that facilitate the local polarization enhancement. It is the combination effect of stable ferroelectric polarization in the PLZT(T) layer, interfacial oxygen vacancies and large surface to volume ratio that leads to the superior polarization performance of the antiferroelectric sandwich structure. It indicates that interface engineering is a feasible approach to manipulate the ferroic behavior.