Reversibly controlled ternary polar states and ferroelectric bias promoted by boosting square-tensile-strain

TL;DR

This paper demonstrates reversible control of ternary polar states in ferroelectric BaTiO3 by boosting square-tensile-strain using BaZrO3 substrates, enabling switchable dielectric states for non-volatile memory applications.

Contribution

It introduces a method to manipulate defect-dipoles and polarization states in ferroelectrics through strain engineering and defect control, advancing heteroepitaxy techniques.

Findings

Reversible switching between ferroelectric and pinched states achieved.

Demonstration of electrically controlled, non-volatile dielectric states.

Promotion of four-variant in-plane polarization via strain and defect engineering.

Abstract

Interaction between dipoles often emerges intriguing physical phenomena, such as exchange bias in the magnetic heterostructures and magnetoelectric effect in multiferroics, which lead to advances in multifunctional heterostructures. However, the defect-dipole tends to be considered the undesired to deteriorate the electronic functionality. Here, we report deterministic switching between the ferroelectric and the pinched states by exploiting a new substrate of cubic perovskite, BaZrO$_{3}$, which boosts square-tensile-strain to BaTiO$_{3}$ and promotes four-variants in-plane spontaneous polarization with oxygen vacancy creation. First-principles calculations propose a complex of an oxygen vacancy and two Ti$^{3+}$ ions coins a charge-neutral defect-dipole. Cooperative control of the defect-dipole and the spontaneous polarization reveals ternary in-plane polar states characterized by biased/pinched hysteresis loops. Furthermore, we experimentally demonstrate that three electrically controlled polar-ordering states lead to switchable and non-volatile dielectric states for application of non-destructive electro-dielectric memory. This discovery opens a new route to develop functional materials via manipulating defect-dipoles and offers a novel platform to advance heteroepitaxy beyond the prevalent perovskite substrates.