2D ferroelectricity in van-der-Waals-stacked materials such as indium selenide (In₂Se₃) has attracted interests because the ferroelectricity is robust even in ultrathin layers, which is useful for the miniaturization of ferroelectric field effect transistors. To implement In₂Se₃ in nanoscale ferroelectric devices, an understanding of the domain structure and switching dynamics in the 2D limit is essential. In this study, a biased scanning tunnelling microscopy (STM) tip is used to locally switch polarized domains in β′-In₂Se₃, and the reconfiguration of these domains are directly visualized using STM. The room-temperature surface of β′-In₂Se₃ breaks into 1D nanostriped domains, which changes into a zig-zag striped domains of β″ phase at low temperatures. These two types of domains can coexist, and by applying a tip-sample bias, they can be interchangeably switched locally, showing volatile or nonvolatile like behavior depending on the threshold voltage applied. An atomic model is proposed to explain the switching mechanism based on tip-induced flexoelectric effect and the ferroelastic switching between β′ and β″ phases.

中文翻译：

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β'-In2Se3 中电切换条纹域的原子成像

硒化铟 (In ₂ Se ₃ )等范德瓦尔斯堆叠材料中的二维铁电性引起了人们的兴趣，因为即使在超薄层中铁电性也很稳定，这对于铁电场效应晶体管的小型化很有用。为了在纳米级铁电器件中实现 In ₂ Se ₃，了解二维极限中的畴结构和开关动力学是必不可少的。在这项研究中，偏置扫描隧道显微镜 (STM) 尖端用于局部切换β '-In ₂ Se _{3 中的}偏振域，这些域的重新配置使用 STM 直接可视化。β的室温表面'-In ₂ Se ₃断裂成一维纳米条纹畴，在低温下转变为β ''相的锯齿状条纹畴。这两种类型的域可以共存，并且通过应用尖端样本偏置，它们可以在本地互换，根据施加的阈值电压显示易失性或非易失性行为。提出了一个原子模型来解释基于尖端诱导的挠电效应和β ' 和β ' 相之间的铁弹性切换的切换机制。