Atomic-scale observations of electrical and mechanical manipulation of topological polar flux-closure

TL;DR

This study uses atomic-scale microscopy to demonstrate reversible manipulation of topological polar flux-closure structures in PbTiO3/SrTiO3 superlattices via electric fields and mechanical stress, revealing insights into their lattice-charge interactions.

Contribution

It provides the first atomic-scale observations of reversible switching of topological polar flux-closure structures under external stimuli.

Findings

Flux-closure structures can be reversibly switched to mono ferroelectric domains.

Electric fields induce flux-closure movement and intermediate striped domains.

Mechanical stress transforms flux-closures into vortices and dipole waves.

Abstract

The ability to controllably manipulate the complex topological polar configurations, such as polar flux-closure via external stimuli, enables many applications in electromechanical devices and nanoelectronics including high-density information storage. Here, by using the atomically resolved in situ scanning transmission electron microscopy, we find that a polar flux-closure structure in PbTiO3/SrTiO3 superlattices films can be reversibly switched to ordinary mono ferroelectric c domain or a domain under electric field or stress. Specifically, the electric field initially drives the flux-closure move and breaks them to form intermediate a/c striped domains, while the mechanical stress firstly starts to squeeze the flux-closures to convert into small vortices at the interface and form a continues dipole wave. After the removal of the external stimuli, the flux-closure structure spontaneously returns. Our atomic study provides valuable insights into understanding the lattice-charge interactions and the competing interactions balance in these complex topological structures. Such reversible switching between the flux-closure and ordinary ferroelectric domains also provides the foundation for applications such as memories and sensors.