Abstract：
Charge density waves (CDWs) in 1T-TaS2 maintain 2D ordering by forming periodic in-plane star-of-David (SOD) patterns, while they also intertwined with orbital order in the c axis. Recent theoretical calculations and surface measurements have explored 3D CDW configurations, but interlayer intertwining of a 2D CDW order remains elusive. Here, we investigate the in- and out-of-plane ordering of the commensurate CDW superstructure in a 1T-TaS2 thin flake in real space, using aberration-corrected cryogenic transmission electronic microscopy (cryo-TEM) in low-dose mode, far below the threshold dose for an electron-induced CDW phase transition. By scrutinizing the phase intensity variation of modulated Ta atoms, we visualize the penetrative 3D CDW stacking structure, revealing an intertwining multidomain structure with three types of vertical CDW stacking configurations. Our results provide microstructural evidence for the coexistence of local Mott insulation and metal phases and offer a paradigm for studying the CDW structure and correlation order in condensed-matter physics using cryo-TEM.
摘要：
1T-TaS2中的电荷密度波（CDW）通过形成周期性的平面内大卫星（SOD）模式来保持2D有序，同时它们也在c轴上与轨道顺序交织在一起。最近的理论计算和表面测量已经探索了3DCDW配置，但是2DCDW顺序的层间交织仍然难以捉摸。这里,我们研究了真实空间中1T-TaS2薄片中相应的CDW上层结构的平面内和平面外顺序，在低剂量模式下使用像差校正的低温透射电子显微镜（cryo-TEM），远低于电子诱导CDW相变的阈值剂量。通过仔细检查调制Ta原子的相位强度变化，我们可视化了穿透式3DCDW堆叠结构，揭示了具有三种类型的垂直CDW堆叠配置的交织多域结构。我们的结果为局部莫特绝缘和金属相共存提供了微观结构证据，并为使用低温TEM研究凝聚态物理中的CDW结构和相关顺序提供了范例。
