二维Lieb锡薄膜的生长及拓扑量子态的调控

二维Lieb阻错晶格有随结构可调的新奇拓扑量子态，包括电子平带和节线电子态等。最近我们刚在实验上获得突破，国际上首次制备了具有Lieb结构的二维锡薄膜。研究发现二维Lieb锡薄膜结构稳定并承载高质量二维电子气，存在受镜面对称性保护的节线电子态，有望成为一个新的研究领域。本项目将针对二维Lieb锡薄膜的生长和拓扑性质调控等方面开展研究工作。拟利用分子束外延技术在不同类型衬底上实现高质量、大面积的二维Lieb锡薄膜的制备。利用各种表面分析手段，深入研究其电子结构、晶格振动、化学稳定性等基本性质，实现二维Lieb锡薄膜与衬底的分离并构筑原型电子器件，研究其电输运和量子输运特性。利用衬底样品相互作用、掺杂吸附等方法，探索调控二维Lieb锡薄膜拓扑量子态的手段，并探讨验证拓扑量子特性的本质和产生原因。我们期望通过本项目对二维Lieb锡薄膜的研究，提供理解和调制二维阻错材料新奇量子效应的可靠技术手段。

Two-dimensional (2D) materials with a Lieb lattice host exotic electronic band structures, including electronic flat band states and nodal line states. Such a system does not exist in nature, and it is also difficult to obtain in the laboratory due to its structural instability. Very recently, we experimentally realized a 2D system composed of a tin overlayer on an Al(100) substrate by molecular beam epitaxy, which is named 2D Lieb stanene. Its 2D Lieb lattice structure is robust which is given rise to the favourable interface interactions. High quality 2D electron gas together with a partially broken nodal line (NL) loop protected by its mirror reflection symmetry. This project will be centered on the exploration of growth mechanism and development of the approaches to manipulate topological quantum properties in 2D Lieb stanene. We will use molecular beam epitaxial method to realise large-scale high-quality 2D Lieb stanene on various substrates including metallic and insulating ones. By using surface and interface characterizations, we will investigate the properties of 2D Lieb stanene, such as electronic structures, phonon modes, and stability. It is targeted to obtained free-standing 2D Lieb stanene sample followed by the fabrication of prototype electronic device. The electric and quantum transport behaviour will be studied. The mechanisms behind quantum phenomena in 2D Lieb stanene will be revealed by the studies on sample-substrate interaction and doping effects. This project will pave a way for constructing 2D quantum materials with tunable topological properties based on the 2D frustrated Lieb lattices.