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Abstract：
Vertical charge order shapes the electronic properties in layered charge density wave (CDW) materials. Various stacking orders inevitably create nanoscale domains with distinct electronic structures inaccessible to bulk probes. Here, the stacking characteristics of bulk 1T-TaS2 are analyzed using scanning tunneling spectroscopy (STS) and density functional theory (DFT) calculations. It is observed that Mott-insulating domains undergo a transition to band-insulating domains restoring vertical dimerization of the CDWs. Furthermore, STS measurements covering a wide terrace reveal two distinct band insulating domains differentiated by band edge broadening. These DFT calculations reveal that the Mott insulating layers preferably reside on the subsurface, forming broader band edges in the neighboring band insulating layers. Ultimately, buried Mott insulating layers believed to harbor the quantum spin liquid phase are identified. These results resolve persistent issues regarding vertical charge order in 1T-TaS2, providing a new perspective for investigating emergent quantum phenomena in layered CDW materials.
摘要：
垂直电荷顺序塑造了层状电荷密度波（CDW）材料的电子特性。各种堆叠顺序不可避免地产生具有本体探针无法接近的不同电子结构的纳米级域。这里,使用扫描隧道光谱（STS）和密度泛函理论（DFT）计算分析了块状1T-TaS2的堆积特性。观察到，Mott绝缘域经历了向带状绝缘域的过渡，恢复了CDW的垂直二聚化。此外，覆盖宽露台的STS测量结果揭示了两个不同的带状绝缘域，它们通过带状边缘加宽而区分开来。这些DFT计算表明，莫特绝缘层优选位于地下，在相邻的带绝缘层中形成更宽的带边缘。最终,确认了被认为含有量子自旋液相的埋藏的Mott绝缘层。这些结果解决了有关1T-TaS2中垂直电荷顺序的持续问题，为研究层状CDW材料中的新兴量子现象提供了新的视角。
