Real-Time Transformation of Flux-Closure Domains with Superhigh Thermal Stability

Polar topologies have received extensive attention due
to their
exotic configurations and functionalities. Understanding their responsive
behaviors to external stimuli, especially thermal excitation, is highly
desirable to extend their applications to high temperature, which
is still unclear. Here, combining in situ transmission
electron microscopy and phase-field simulations, the thermal dynamics
of the flux-closure domains were illuminated in PbTiO3/SrTiO3 multilayers. In-depth analyses suggested that the topological
transition processes from a/c domains
to flux-closure quadrants were influenced by the boundary conditions
of PbTiO3 layers. The symmetrical boundary condition stabilized
the flux-closure domains at higher temperature than in the asymmetrical
case. Furthermore, the reversible thermal responsive behaviors of
the flux-closure domains displayed superior thermal stability, which
maintained robust up to 450 °C (near the Curie temperature).
This work provides new insights into the dynamics of polar topologies
under thermal excitation and facilitates their applications as nanoelectronics
under extreme conditions.

极性拓扑结构（polar topologies）因其独特的构型与功能特性而受到广泛关注。厘清其对外界刺激（尤其是热激发）的响应行为，对于将其应用拓展至高温环境至关重要，但目前相关机制仍不明确。本研究结合原位透射电子显微镜（in situ transmission electron microscopy）与相场模拟（phase-field simulations），阐明了钛酸铅/钛酸锶多层膜（PbTiO3/SrTiO3 multilayers）中通量闭合畴（flux-closure domains）的热动力学行为。深入分析表明，从a/c畴（a/c domains）到通量闭合四极畴的拓扑转变过程，受钛酸铅层的边界条件调控。相较于非对称边界条件，对称边界条件可使通量闭合畴在更高温度下保持稳定。此外，通量闭合畴的可逆热响应行为展现出优异的热稳定性，可在高达450℃（接近居里温度（Curie temperature））的环境中保持结构稳定。本研究为热激发下极性拓扑结构的动力学行为提供了全新认知，并为其在极端条件下作为纳米电子学（nanoelectronics）器件的应用提供了助力。