Khan Muhammad Shuaib, Osada Minoru, Dong Lei, Kim Yoon-Hyun, Ebina Yasuo, Sasaki Takayoshi
International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0044, Japan.
Department of Nanoscience and Engineering, Waseda University, Shinjyuku, Tokyo 169-8555, Japan.
ACS Appl Mater Interfaces. 2021 Jan 13;13(1):1783-1790. doi: 10.1021/acsami.0c16967. Epub 2020 Dec 21.
Artificial materials in the form of superlattices have been studied actively in quest of new engineering methods or design rules for the development of desired functionalities, in particular high- ferroelectricity, ferromagnetism, and high mobility electron gas. This work presents a controlled assembly strategy for fabricating atomically precise interfaces of two-dimensional (2D) homologous perovskite nanosheets (CaNaNbO; = 3-6) to construct artificial superlattices. The distinctive thickness of each 2D homologous perovskite nanosheets attributed to the presence of different number of NbO octahedra provides an exquisite control to engineer interfacial properties for tailored design of superior high- properties and emergence of ferroelectricity. The higher dielectric constant (ε = 427) and development of ferroelectricity for (CaNbO/CaNaNbO) superlattice indicate that superlattice films with both odd number of NbO octahedra possess extended polarization due to the potential effect of heterointerface and ferroelectric instabilities. Furthermore, the increased discontinuities/offsets in CaNbO and CaNaNbO nanosheets band alignment results in superior insulating properties (∼1 × 10 A cm at 1 V) for (CaNbO/CaNaNbO) superlattice. These findings exhibit new research opportunities for the development of novel artificial high- dielectric/ferroelectric via precise control of interfaces at the atomic level and can be extended to the large family of 2D perovskite compounds.
为了寻求用于开发所需功能，特别是高铁电性、铁磁性和高迁移率电子气的新工程方法或设计规则，人们积极研究了超晶格形式的人工材料。这项工作提出了一种可控组装策略，用于制造二维（2D）同系钙钛矿纳米片（CaNaNbO；n = 3 - 6）的原子精确界面，以构建人工超晶格。每个二维同系钙钛矿纳米片独特的厚度归因于不同数量的NbO八面体的存在，这为设计界面特性提供了精确控制，以定制设计卓越的高性能和铁电性的出现。（CaNbO/CaNaNbO）超晶格的较高介电常数（ε = 427）和铁电性的发展表明，由于异质界面和铁电不稳定性的潜在影响，具有奇数个NbO八面体的超晶格薄膜具有扩展极化。此外，CaNbO和CaNaNbO纳米片能带排列中增加的不连续性/偏移导致（CaNbO/CaNaNbO）超晶格具有优异的绝缘性能（在1 V时约为1×10 A/cm）。这些发现为通过在原子水平上精确控制界面来开发新型人工高介电/铁电材料展示了新的研究机会，并且可以扩展到二维钙钛矿化合物的大家族。
