Emergence of Polar Vortex-Antivortex Pair Arrays in Multiferroic Superlattices.

Abstract

Ferroelectric topologies, renowned for their nanoscale dimensions and external electric field tunability, are emerging as leading candidates for high-density, low-power memory devices in the Big Data era. While polar configurations such as vortices, flux-closure domains, center-type domains, skyrmions, and merons have been extensively explored, antivortices remain largely underdeveloped. In this work, the discovery and realization of stable polar vortex-antivortex pair arrays within multiferroic-dielectric superlattices are reported with integrated experimental and theoretical efforts, enabled by low-symmetry BiFeO3 with diagonal spontaneous polarization. By employing atomic-level engineering to precisely modulate the architecture of BiFeO3 layers, achieving unprecedented periodicities as small as 4.5 nm. These arrays exhibit exceptional thermal stability, preserving their structural integrity above room temperature, and reversible polarization switching under applied electric fields. Additionally, the sensitivity of domain wall configurations to the dielectric layer thickness offers further tunability. These findings not only expand the scope of ferroelectric topologies but also provide a versatile platform for harnessing antivortices in practical applications, paving the way for next-generation ultrahigh-density, low-power memory technologies.