Anti-polar state in BiFeO3/NdFeO3 superlattices

TL;DR

This study demonstrates the fabrication of BiFeO3/NdFeO3 superlattices exhibiting anti-polar ordering, revealing potential for energy storage and nano-electronic applications through atomic-scale structural analysis.

Contribution

It introduces a new nanoscale superlattice design with anti-polar order, expanding the understanding of ferroelectric-like behaviors in rare-earth oxide superlattices.

Findings

Anti-polar ordering observed in BiFeO3/NdFeO3 superlattices

Anti-polar state stability depends on BiFeO3 layer thickness

Structural transition influenced by interlayer strain

Abstract

Antiferroelectrics are promising materials for high energy density capacitors and the search for environmentally-friendly and efficient systems is actively pursued. An elegant strategy to create and design new (anti)ferroic system relies on the use of nanoscale superlattices. We report here the use of such strategy and the fabrication of nanoscale BiFeO3/NdFeO3 superlattices and in depth characterization using high resolution X-ray diffraction and Transmission Electron Microscopy. The structural analysis at atomic scale demonstrates that such superlattices host anti-polar ordering most likely described by an antiferroelectric-like Pbnm symmetry. Temperature dependence of anti-polar state and structural transition further hint that the stability of the anti-polar state is controlled by the BiFeO3 layer thickness within the stacking and, in a more moderate way, by interlayer strain. Discovery of such polar arrangement in superlattices and the possible generalization to the whole rare-earth family pave the way to new platforms for energy storage application as well as nano-electronic devices.