Xu Yang, Horn Connor, Zhu Jiacheng, Tang Yanhao, Ma Liguo, Li Lizhong, Liu Song, Watanabe Kenji, Taniguchi Takashi, Hone James C, Shan Jie, Mak Kin Fai
School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA.
Department of Mechanical Engineering, Columbia University, New York, NY, USA.
Nat Mater. 2021 May;20(5):645-649. doi: 10.1038/s41563-020-00888-y. Epub 2021 Jan 21.
Moiré superlattices of two-dimensional van der Waals materials have emerged as a powerful platform for designing electronic band structures and discovering emergent physical phenomena. A key concept involves the creation of long-wavelength periodic potential and moiré bands in a crystal through interlayer electronic hybridization or atomic corrugation when two materials are overlaid. Here we demonstrate a new approach based on spatially periodic dielectric screening to create moiré bands in a monolayer semiconductor. This approach relies on reduced dielectric screening of the Coulomb interactions in monolayer semiconductors and their environmental dielectric-dependent electronic band structure. We observe optical transitions between moiré bands in monolayer WSe when it is placed close to small-angle-misaligned graphene on hexagonal boron nitride. The moiré bands are a result of long-range Coulomb interactions, which are strongly gate tunable, and can have versatile superlattice symmetries independent of the crystal lattice of the host material. Our result also demonstrates that monolayer semiconductors are sensitive local dielectric sensors.
二维范德华材料的莫尔超晶格已成为设计电子能带结构和发现新出现物理现象的强大平台。一个关键概念涉及当两种材料叠加时，通过层间电子杂化或原子起伏在晶体中创建长波长周期性势和莫尔能带。在此，我们展示了一种基于空间周期性介电屏蔽的新方法，用于在单层半导体中创建莫尔能带。这种方法依赖于单层半导体中库仑相互作用的介电屏蔽降低以及它们与环境介电相关的电子能带结构。当单层WSe₂放置在六方氮化硼上与小角度错位的石墨烯靠近时，我们观察到了莫尔能带之间的光学跃迁。莫尔能带是长程库仑相互作用的结果，这种相互作用可通过栅极强烈调节，并且可以具有独立于主体材料晶格的多种超晶格对称性。我们的结果还表明单层半导体是灵敏的局部介电传感器。
