过渡金属氧化物的d轨道电子间具有较强的关联作用，其异质界面在对称性破缺和维度限制下可形成体块材料中不存在的新颖量子现象（如二维电子气2DEG），有望成为下一代电子器件的基础。目前，氧化物界面2DEG研究主要局限于钙钛矿结构氧化物中，其内在机理特别是氧缺陷的作用还存在若干争议，在新材料体系中实现和研究2DEG现象有望成为一个新的突破口。层状类钙钛矿结构与钙钛矿结构氧化物具有很多的相似性和差异性，为深入理解2DEG的机理及发现新颖界面量子现象带来了新的机遇。最近，申请者在层状类钙钛矿氧化物微观生长机制方面取得了重要的研究进展，利用氧化物分子束外延（MBE）技术制备出原子精度的明锐异质界面，使得研究基于非钙钛矿结构的氧化物界面成为了可能。本课题拟应用氧化物MBE研究基于层状类钙钛矿结构的异质界面，深入揭示2DEG的产生机理，实现二维应力及外场对界面效应的调控，并探索新型界面量子现象。

Heterointerfaces between strongly correlated transition-metal oxides have been proven to be ideal platforms for investigating new physical phenomena, such as the two dimensional electron gas (2DEG), shedding light on the next generation multifunctional oxide electrons. Up to date, the studies of 2DEG have been mainly focused on a single type of materials (ABO3 perovskites), however, the underlying physics, especially the role of oxygen vacancies, is still elusive and under hot debate. Investigating heterointerfaces made up of non-perovskite oxides is of great interests in providing deeper understanding of 2DEG and in searching of other emergent interfacial quantum phenomena. Recently, we have uncovered the microscopic growth mechanism of an important class of layered perovskites (Ruddlesden-Popper series) and obtained their atomically precise interfaces using an improved layer-by-layer growth technique employed in oxide molecular beam expitaxy (MBE). This breakthrough enables the investigation of 2DEG in a new type of oxide interfaces made up of layered perovskites, paving the way to a more complete understanding of 2DEG. In this project, we propose the study of heterointerfaces based on layered perovskites using oxide MBE in understanding the physics of 2DEG. Novel interfacial quantum phenomena and the engineering of these interfacial effects by epitaxial strain and external field will be also investigated.