Control of ferroelectric polarization in BiFeO3 bilayer films through interface engineering

Abstract

Abstract Predetermining the as-grown polarization of ferroelectric thin films is essential to integrate their reliable properties into electronic devices. However, studies have so far focused mainly on the control of the polarization state of a single ferroelectric layer. Here we report a strategy for the artificial modulation of pristine polarization in BiFeO3 bilayer films. We have fabricated multilayers of BiFeO3/SrTiO3/BiFeO3 on single-crystalline SrTiO3 (001) substrates. It is found that the out-of-plane polarization components of the BiFeO3 bilayer can be controlled by modifying the surface terminations of SrTiO3 interlayer and SrTiO3 substrate. Using aberration-corrected scanning transmission electron microscopy, we directly visualize the head-to-head and tail-to-tail polarization configurations formed by the BiFeO3 bilayers. Polar discontinuity at the ferroelectric/non-ferroelectric interface is the reason for tuning the orientation of electrical polarization. Our work provides an effective route to design fascinating ferroelectric multilayers with well-defined polarization direction.