極性拓樸渦漩結構在鐵電材料中展現出極佳的穩定性與非揮發性，為次世代記憶與運算元件提供了全新的物理平台。然而，過往實現此類結構大多依賴於特定超晶格堆疊或材料結構條件，嚴重限制其可製性與設計自由度。本研究提出一套基於人工蝕刻孔洞與幾何排列設計的應變調控策略，於 BiFeO₃薄膜系統中成功穩定誘導並排列出中心型極性拓樸渦漩陣列，同時實現對其拓樸狀態的可逆電場操控。
在 LSMO/STO(001)磊晶薄膜上，我們先以濕蝕刻製作具不同直徑與間距的人工孔洞，再於其上磊晶生長BFO薄膜。當孔洞直徑縮小至約200 nm且排列間距控制於600 nm左右時，BFO在蝕刻孔洞及其間距區域皆形成高品質的中心型頭對頭極性拓樸渦漩，展現出清晰的極性紋理排列。更進一步地，我們透過壓電力顯微鏡（PFM）進行局域電場驅動，觀察到中心型極性拓樸渦漩可被電性切換操控，其中纏繞數的切換明顯與極性拓樸結構的轉變對應，顯示其拓樸狀態受電場驅動的可重構性與穩定性，為未來非揮發性記憶元件與拓樸記憶邏輯運算奠定可行性。
本研究亦透過CAFM、FM-KPFM與QNM等手段初步探討此類拓樸結構的導電性與力學特性，並觀察到頭對頭極性渦漩處具有相對較高導電與較低楊氏模數的性質。更重要的是，本研究不僅透過探針施加電場的軌跡操作實現了渦漩陣列的操控，最終更利用探針所產生的尾隨饒曲電場成功驅動陣列進行極化翻轉，並顯示出相較於外加電場更少的電荷注入效應。這些成果不僅證實了中心型極性拓樸渦漩的穩定性與高度可操控性，也展現出結合應變設計與多元外場策略在鐵電拓樸研究與應用上的廣闊前景。

Polar topological vortex structures in ferroelectric materials exhibit outstanding stability and non-volatility, providing a novel physical platform for next-generation memory and computing devices. However, previous demonstrations of such structures have largely depended on specific superlattice configurations or rigid material constraints, severely restricting their manufacturability and design flexibility. In this study, we propose a strain engineering strategy based on artificially etched holes and geometric pattern design, enabling the robust induction and ordered arrangement of center-type polar vortex arrays in BiFeO₃ (BFO) thin films, while simultaneously achieving reversible electric-field control of their topological states. Epitaxial La₀.₇Sr₀.₃MnO₃ (LSMO) films were first deposited on (001)-oriented SrTiO₃ (STO) substrates, followed by wet etching to define artificial holes with varied diameters and spacings. Subsequent BFO growth atop these patterned templates yielded well-ordered, center-convergent head-to-head vortices both at the etched holes and in the inter-hole regions when the hole diameter was reduced to ~200 nm and the spacing was ~600 nm. The resulting vortex arrays displayed clear polar texture alignment. Using Piezoresponse Force Microscopy (PFM), we demonstrated that these center-type vortices can be reversibly switched by localized electric fields, with changes in the winding number directly correlated to transformations of the polar textures. This reveals the reconfigurability and stability of their topological states under electric bias, laying the foundation for non-volatile topological memory and logic devices. We further employed Conductive Atomic Force Microscopy (C-AFM), Frequency-Modulated Kelvin Probe Force Microscopy (FM-KPFM), and Quantitative Nanomechanical Mapping (QNM) to probe the electronic and mechanical properties of these structures. Head-to head vortex cores exhibited enhanced conductivity and reduced Young’s modulus, underscoring the intimate coupling between polar topology, charge transport, and local mechanical softness. More importantly, by exploiting the trajectory of probe-induced electric fields, we achieved array-level manipulation of vortex states and, notably, demonstrated polarization switching of vortex arrays driven by trailing flexoelectric fields generated by the scanning probe. This approach produced switching with minimal charge injection compared to conventional uniform electric fields. Collectively, these findings confirm the intrinsic stability and high tunability of center-type polar vortices and highlight the potential of combining strain design with multifield control strategies for advancing ferroelectric topological research and applications.

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