Continuously tunable ferroelectric domain width down to the single-atomic limit in bismuth tellurite.

Han, Mengjiao; Wang, Cong; Niu, Kangdi; Yang, Qishuo; Wang, Chuanshou; Zhang, Xi; Dai, Junfeng; Wang, Yujia et al. · Nat Commun · 2022

basic_science · Level V

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Abstract

Emerging functionalities in two-dimensional materials, such as ferromagnetism, superconductivity and ferroelectricity, open new avenues for promising nanoelectronic applications. Here, we report the discovery of intrinsic in-plane room-temperature ferroelectricity in two-dimensional Bi<sub>2</sub>TeO<sub>5</sub> grown by chemical vapor deposition, where spontaneous polarization originates from Bi column displacements. We found an intercalated buffer layer consist of mixed Bi/Te column as 180° domain wall which enables facile polarized domain engineering, including continuously tunable domain width by pinning different concentration of buffer layers, and even ferroelectric-antiferroelectric phase transition when the polarization unit is pinned down to single atomic column. More interestingly, the intercalated Bi/Te buffer layer can interconvert to polarized Bi columns which end up with series terraced domain walls and unusual fan-shaped ferroelectric domain. The buffer layer induced size and shape tunable ferroelectric domain in two-dimensional Bi<sub>2</sub>TeO<sub>5</sub> offer insights into the manipulation of functionalities in van der Waals materials for future nanoelectronics.