Single-water-dipole-layer-driven Reversible Charge Order Transition in 1T-TaS2.
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 1T-TaS2 driven by a single water dipole layer. At low temperature, pristine 1T-TaS2 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 1T-TaS2. After water desorption, the entire 1T-TaS2 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 1T-TaS2, 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.
['Shen|Shiwei|S|', 'Shao|Bin|B|http://orcid.org/0000-0002-9953-7275', 'Wen|Chenhaoping|C|', 'Yuan|Xiaoqiu|X|', 'Gao|Jingjing|J|http://orcid.org/0000-0002-0791-4951', 'Nie|Zhengwei|Z|', 'Luo|Xuan|X|http://orcid.org/0000-0002-0482-4096', 'Huang|Bing|B|', 'Sun|Yuping|Y|', 'Meng|Sheng|S|http://orcid.org/0000-0002-1553-1432', 'Yan|Shichao|S|http://orcid.org/0000-0002-7318-300X']
reversible charge order transition 1T-TaS2 water dipole layer CDW domain walls interfacial water