Observation of Possible Ferroelectric Vortices in Bismuth Square Islands.

Xue, Sha-Sha; Zhong, Shulin; Guan, Dandan; Liu, Dang; Yu, Qiao-Yan; Xi, Ruijun; Chen, Xingsen; Sun, Ji-Ce et al. · ACS Nano · 2026

basic_science · Level V

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Abstract

Ferroelectric vortices, with their unique topological polarization patterns, show great potential for next-generation electronics. Although they have been observed in compounds, their realization in single-element materials has remained elusive. Here, we experimentally prepare three-bilayer Bi(110) square-shaped islands on high-<i>T</i><sub><i>C</i></sub> superconductor (Bi<sub>2</sub>Sr<sub>2</sub>CaCu<sub>2</sub>O<sub>8+δ</sub>) substrates by molecular beam epitaxy. Scanning tunneling microscopy/spectroscopy combined with first-principles calculations suggests the possible existence of in-plane polarization and a ferroelectric vortex state in our islands, as well as reveals exceptional vortex stability against electric-field-driven switching. This work could pioneer single-element ferroelectric vortices, potentially advancing topological ferroelectrics design and expanding the understanding of related fundamental physics.