Single-water-dipole-layer-driven Reversible Charge Order Transition in 1 T -TaS 2

作者：Shiwei Shen, Bin Shao, Chenhaoping Wen, Xiaoqiu Yuan, Jingjing Gao, Zhengwei Nie, Xuan Luo, Bing Huang, Yuping Sun, Sheng Meng, Shichao Yan · 发表于：Nano Letters · 年份：2020 · DOI：10.1021/acs.nanolett.0c03857 · 被引用次数：17 · 研究领域：2D Materials and Applications、Electronic and Structural Properties of Oxides、Molecular Junctions and Nanostructures

Water–solid interactions are crucial for many fundamental phenomena and technological processes. Here, we report a scanning tunneling microscopy study about the charge density wave (CDW) transition in 1 T -TaS 2 driven by a single water dipole layer. At low temperature, pristine 1 T -TaS 2 is a prototypical CDW compound with × charge order. After growing a highly ordered water adlayer, a new charge order with 3 × 3 periodicity emerges on water-covered 1 T -TaS 2 . After water desorption, the entire 1 T -TaS 2 surface appears as localized × CDW domains that are separated by residual-water-cluster-pinned CDW domain walls. First-principles calculations show that the electric dipole moments in the water adlayer attract electrons to the top layer of 1 T -TaS 2, which shifts the phonon softening mode and induces the × to 3 × 3 charge order transition. Our results pave the way for creating new collective quantum states of matter with a molecular dipole layer.