Hybrid antiferroelectric-ferroelectric domain walls in noncollinear antipolar oxides

TL;DR

This paper reveals that noncollinear electric dipole order in certain oxides enables coexistence of antiferroelectric and ferroelectric behaviors, leading to novel domain wall phenomena and multifunctional properties.

Contribution

It demonstrates noncollinearity as a new degree of freedom in antiferroelectrics, unlocking symmetry-forbidden physical properties and hybrid responses in noncollinear oxides.

Findings

Observation of coexistence of antiferroelectric and ferroelectric behaviors.

Detection of atomically sharp charged domain walls.

Presence of switchable domains with pronounced piezoresponse.

Abstract

Antiferroelectrics are emerging as advanced functional materials and are fertile ground for unusual electric effects. For example, they enhance the recoverable energy density in energy storage applications and give rise to large electromechanical responses. Here, we demonstrate noncollinearity in dipolar order as an additional degree of freedom, unlocking physical properties that are symmetry-forbidden in classical antiferroelectrics. We show that noncollinear order of electric dipole moments in K$_3$[Nb$_3$O$_6$|(BO$_3$)$_2$] leads to a coexistence of antiferroelectric and ferroelectric behaviors. Besides the double-hysteresis loop observed in antiferroelectrics, a pronounced piezoresponse and electrically switchable domains are observed, separated by atomically sharp and micrometer-long charged domain walls. Hybrid antiferroelectric-ferroelectric responses are expected in a wide range of noncollinear systems, giving a new dimension to the research on antiferroelectrics and multifunctional oxides in general.