Moiré superlattices in transition metal dichalcogenide (TMD) heterostructures can host novel correlated quantum phenomena due to the interplay of narrow moiré flat bands and strong, long-range Coulomb interactions^{1,2,3,4,5,6,7,8,9}. However, microscopic knowledge of the atomically reconstructed moiré superlattice and resulting flat bands is still lacking, which is critical for fundamental understanding and control of the correlated moiré phenomena. Here we quantitatively study the moiré flat bands in three-dimensional (3D) reconstructed WSe₂/WS₂ moiré superlattices by comparing scanning tunnelling spectroscopy (STS) of high-quality exfoliated TMD heterostructure devices with ab initio simulations of TMD moiré superlattices. A strong 3D buckling reconstruction accompanied by large in-plane strain redistribution is identified in our WSe₂/WS₂ moiré heterostructures. STS imaging demonstrates that this results in a remarkably narrow and highly localized K-point moiré flat band at the valence band edge of the heterostructure. A series of moiré flat bands are observed at different energies that exhibit varying degrees of localization. Our observations contradict previous simplified theoretical models but agree quantitatively with ab initio simulations that fully capture the 3D structural reconstruction. Our results reveal that the strain redistribution and 3D buckling in TMD heterostructures dominate the effective moiré potential and the corresponding moiré flat bands at the Brillouin zone K points.

由于窄莫尔平带和强长程库仑相互作用^{1,2,3,4,5,6,7,8,9}的相互作用，过渡金属二硫属化物 (TMD) 异质结构中的莫尔超晶格可以承载新的相关量子现象. 然而，仍然缺乏对原子重建的莫尔超晶格和由此产生的平带的微观知识，这对于基本理解和控制相关的莫尔现象至关重要。在这里，我们定量研究三维（3D）重建的WSe ₂ /WS _{2 中}的莫尔平坦带通过比较高质量剥离 TMD 异质结构器件的扫描隧道光谱 (STS) 与 TMD 莫尔超晶格的从头算模拟来获得莫尔超晶格。在我们的 WSe ₂ /WS _{2 中}发现了一个强大的 3D 屈曲重建以及大的平面内应变重新分布莫尔异质结构。STS 成像表明，这会在异质结构的价带边缘产生非常窄且高度局部化的 K 点莫尔平带。在不同的能量下观察到一系列莫尔平坦带，这些带表现出不同程度的定位。我们的观察结果与之前的简化理论模型相矛盾，但在数量上与完全捕捉 3D 结构重建的从头模拟一致。我们的结果表明，TMD 异质结构中的应变重新分布和 3D 屈曲在布里渊区 K 点处主导有效莫尔势和相应的莫尔平带。