Wang Hongfei, Ma Shaojie, Zhang Shuang, Lei Dangyuan
Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong, 999077, China.
Department of Physics, University of Hong Kong, Hong Kong, 999077, China.
Light Sci Appl. 2022 May 30;11(1):159. doi: 10.1038/s41377-022-00838-0.
Twisted bilayer systems with discrete magic angles, such as twisted bilayer graphene featuring moiré superlattices, provide a versatile platform for exploring novel physical properties. Here, we discover a class of superflat bands in general twisted bilayer systems beyond the low-energy physics of magic-angle twisted counterparts. By considering continuous lattice dislocation, we obtain intrinsic localized states, which are spectrally isolated at lowest and highest energies and spatially centered around the AA stacked region, governed by the macroscopic effective energy potential well. Such localized states exhibit negligible inter-cell coupling and support the formation of superflat bands in a wide and continuous parameter space, which can be mimicked using a twisted bilayer nanophotonic system. Our finding suggests that general twisted bilayer systems can realize continuously tunable superflat bands and the corresponding localized states for various photonic, phononic, and mechanical waves.
具有离散魔角的扭曲双层系统，如具有莫尔超晶格的扭曲双层石墨烯，为探索新型物理性质提供了一个通用平台。在这里，我们在一般扭曲双层系统中发现了一类超平带，超出了魔角扭曲对应物的低能物理范畴。通过考虑连续晶格位错，我们获得了本征局域态，这些态在最低和最高能量处频谱隔离，并且在空间上以AA堆叠区域为中心，由宏观有效能量势阱控制。这种局域态表现出可忽略不计的晶胞间耦合，并在宽广且连续的参数空间中支持超平带的形成，这可以用扭曲双层纳米光子系统来模拟。我们的发现表明，一般扭曲双层系统可以为各种光子、声子和机械波实现连续可调的超平带以及相应的局域态。
