Recently, moiré superlattices of twisted van der Waals (vdW) materials have attracted substantial interest due to their strongly correlated properties. However, the vdW interlayer interaction is intrinsically weak, such that many desired properties can only exist at low temperature. Here, we theoretically predict some unusual properties stemming from the chemical bonding between twisted PbS nanosheets as an example of non-vdW moiré superlattices. The strong interlayer coupling in such systems results in giant strain vortices and dipole vortices at the interface. The modified electronic structures become a series of dispersionless bands and artificial-atom states. In real space, these states are analogous to arrays of well-positioned quantum dots, which may be promising for use in single-electron devices. In theory, if the materials are doped with a low concentration of electrons, a Wigner crystal will form even without any magnetic field. To confirm the accessibility and stability of non-vdW moiré superlattices in experiment, we synthesized PbS moiré superlattices with different twist angles. Our transmission-electron-microscope observations reveal the resemblance of the small-angle-twisted structures with the square matrices of quantum dots, which is in good accordance with our calculations.

中文翻译：

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非范德华材料莫尔超晶格中的深量子点阵列

最近，扭曲范德华 (vdW) 材料的莫尔超晶格由于其强相关特性而引起了极大的兴趣。然而，vdW 层间相互作用本质上是弱的，因此许多所需的特性只能在低温下存在。在这里，我们从理论上预测了一些源自扭曲 PbS 纳米片之间的化学键合的不寻常特性，作为非 vdW 莫尔超晶格的一个例子。这种系统中的强层间耦合导致界面处产生巨大的应变涡和偶极涡。修改后的电子结构变成一系列无色散带和人工原子态。在现实空间中，这些状态类似于定位良好的量子点阵列，可能有望用于单电子器件。理论上，如果材料掺杂了低浓度的电子，即使没有任何磁场也会形成维格纳晶体。为了确认实验中非 vdW 莫尔超晶格的可及性和稳定性，我们合成了具有不同扭转角的 PbS 莫尔超晶格。我们的透射电子显微镜观察揭示了小角度扭曲结构与量子点方阵的相似性，这与我们的计算非常吻合。