Li Yiwei, Wan Qiang, Xu Nan
Institute for Advanced Studies (IAS), Wuhan University, Wuhan, 430072, China.
Wuhan Institute of Quantum Technology, Wuhan, 430206, China.
Adv Mater. 2023 Sep 9:e2305175. doi: 10.1002/adma.202305175.
The last decade has witnessed a flourish in 2D materials including graphene and transition metal dichalcogenides (TMDs) as atomic-scale Legos. Artificial moiré superlattices via stacking 2D materials with a twist angle and/or a lattice mismatch have recently become a fertile playground exhibiting a plethora of emergent properties beyond their building blocks. These rich quantum phenomena stem from their nontrivial electronic structures that are effectively tuned by the moiré periodicity. Modern angle-resolved photoemission spectroscopy (ARPES) can directly visualize electronic structures with decent momentum, energy, and spatial resolution, thus can provide enlightening insights into fundamental physics in moiré superlattice systems and guides for designing novel devices. In this review, first, a brief introduction is given on advanced ARPES techniques and basic ideas of band structures in a moiré superlattice system. Then ARPES research results of various moiré superlattice systems are highlighted, including graphene on substrates with small lattice mismatches, twisted graphene/TMD moiré systems, and high-order moiré superlattice systems. Finally, it discusses important questions that remain open, challenges in current experimental investigations, and presents an outlook on this field of research.
过去十年见证了二维材料（包括石墨烯和过渡金属二硫属化物（TMDs））作为原子级乐高积木的蓬勃发展。通过堆叠具有扭转角和/或晶格失配的二维材料形成的人工莫尔超晶格，最近已成为一个富有成果的研究领域，展现出许多超越其组成部分的涌现特性。这些丰富的量子现象源于它们不平凡的电子结构，这些结构可通过莫尔周期性有效地调节。现代角分辨光电子能谱（ARPES）能够以良好的动量、能量和空间分辨率直接可视化电子结构，从而为莫尔超晶格系统中的基础物理提供有启发性的见解，并为设计新型器件提供指导。在这篇综述中，首先简要介绍了先进的ARPES技术以及莫尔超晶格系统中能带结构的基本概念。然后重点介绍了各种莫尔超晶格系统的ARPES研究成果，包括具有小晶格失配的衬底上的石墨烯、扭曲的石墨烯/TMD莫尔系统以及高阶莫尔超晶格系统。最后，讨论了仍然悬而未决的重要问题、当前实验研究中的挑战，并对该研究领域进行了展望。
