平带二维晶格的原子级精确构筑及其局域态调控研究

具有无色散平带的二维晶格因其高简并局域态电子强关联效应，被预言存在分数量子霍尔效应、铁磁基态以及超导等新奇物理特性。其中超导态在魔角双层石墨烯平带体系中已被证实。然而理论预言的多数新奇物性目前尚待实验探索，主要原因是实验测量所需的平带晶格大多不易用常规方法制备或调控。本项目拟利用扫描隧道显微镜原子操纵技术，以单个原子或分子为格点单元，构筑具有Lieb、Breathing Kagome等平带二维晶格的人工量子结构，并研究这种多参数可调的模型体系中的局域态及其关联效应。为消除衬底费米能级附近电子态对平带的影响，我们将以几种半导体和氧化物为衬底；为实现对平带填充状态的精细调控，我们将通过调控局域表面势来微调体系费米能级位置。我们前期在III-V半导体表面人工量子结构和二维半导体Moire超晶格局域态等方面的工作为此项目奠定了基础。此项目成果将有助于平带局域态在未来信息器件中的应用。

The dispersionless flat band (FB) arising from two dimensional lattices of particular symmetry has attracted lots of research interests due to the strong correlation effects of microscopically degenerated localized states from the FB. It has been predicted that many exotic physical properties, like Fractional Quantum Hall effect, Ferromagnetic ground state and unconventional superconductivity, could be found in such systems. The recently observed superconductor state within the “magic angle” twisted bilayer graphene is a perfect example. However, the predicted 2D lattices with FB are largely unavailable for experimental investigation since they could not be synthesized by conventional growth method so far. We propose to tackle this problem by building atomic precision artificial quantum structures with FB lattices, like Diamond Ladder、Lieb、Breathing Kagome, by means of scanning tunneling microscope (STM) atom manipulation technique. Fine tuning of the lattice parameters and Fermi level could be achieved thanks to the high precision of atom manipulation by STM. Furthermore, the investigation of the compact localized states and strong correlation effect within such structures will be carried out. This study is facilitated by our previous works on the FB localized states of bilayer 2D semiconductors and artificial lattice constructed by atom manipulation on III-V semiconductor surfaces. We anticipate the new physics obtained in this project will be useful for the quantum information storage and processing in next generation electronic devices.