论文标题
过渡金属二甲基元化MoiréBilayers中的旋转和扩张重建
Rotational and Dilational Reconstruction in Transition Metal Dichalcogenide Moiré Bilayers
论文作者
论文摘要
晶格的重建和相应的应变积累在定义二维Moiré超晶格的电子结构（包括过渡金属二甲化剂（TMD））方面起着关键作用。到目前为止，TMDMoirés的成像在层间堆叠能量方面对这种放松过程提供了定性的理解，而潜在变形机制的模型依赖于模拟。在这里，我们使用干涉四维扫描透射电子显微镜来定量地绘制在小角度扭曲的双层MOS2和WSE2/MOS2 Heterobilayers中重建的机械变形。我们提供了直接的证据，表明局部旋转控制着扭曲的同质体的放松，而局部扩张在具有足够大的晶格不匹配的异质分子中是突出的。 HBN中Moiré层的封装进一步定位并增强了这些面内重建途径，从而抑制了平面外瓦楞纸。我们还发现，在扭曲同质体中引入了晶格恒定差异的外部单轴异，可导致重建菌株的积累和重新分布，证明了另一种修改Moiré电位的途径。
Lattice reconstruction and corresponding strain accumulation play a key role in defining the electronic structure of two-dimensional moiré superlattices, including those of transition metal dichalcogenides (TMDs). Imaging of TMD moirés has so far provided a qualitative understanding of this relaxation process in terms of interlayer stacking energy, while models of the underlying deformation mechanisms have relied on simulations. Here, we use interferometric four-dimensional scanning transmission electron microscopy to quantitatively map the mechanical deformations through which reconstruction occurs in small-angle twisted bilayer MoS2 and WSe2/MoS2 heterobilayers. We provide direct evidence that local rotations govern relaxation for twisted homobilayers, while local dilations are prominent in heterobilayers possessing a sufficiently large lattice mismatch. Encapsulation of the moiré layers in hBN further localizes and enhances these in-plane reconstruction pathways, suppressing out-of-plane corrugation. We also find that extrinsic uniaxial heterostrain, which introduces a lattice constant difference in twisted homobilayers, leads to accumulation and redistribution of reconstruction strain, demonstrating another route to modify the moiré potential.
