Microscopically revealing the interactions between interfacial water and the quantum states of matter is an important task from both the materials science and the physics points of view. Here we report a low-temperature scanning tunneling microscopy (STM) and spectroscopy study of water adsorption on the charge density wave compound $1T\text{−}{\mathrm{TaS}}_2$, which has a Mott-insulating ground state. Interfacial water forms monolayer islands with $6\times 6$ superstructures on the surface of $1T\text{−}{\mathrm{TaS}}_2$, and the charge order under water islands can be directly imaged in STM topographies taken with negative bias voltages. Compared with the original $\sqrt{13}\times \sqrt{13}$ charge order in $1T\text{−}{\mathrm{TaS}}_2$, the charge order under water islands becomes significantly disordered and denser. A $\mathsf{V}$-shaped gaplike feature emerges in water-covered $1T\text{−}{\mathrm{TaS}}_2$, which may be due to the enhanced dielectric constant of interfacial water, which reduces short-range Coulomb repulsion and induces Mott gap collapse. Our observations open the way to microscopically understanding the interactions between interfacial water and the correlated quantum states of matter.

中文翻译：

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界面水诱导的1T-TaS2上电荷密度波的熔化和Mott缝隙塌陷

从材料科学和物理学的观点来看，微观地揭示界面水与物质的量子态之间的相互作用是一项重要的任务。在这里我们报告了低温扫描隧道显微镜（STM）和光谱学研究水在电荷密度波化合物上的吸附$\mathrm{1个}Ť\text{-}{钽}_2$具有Mott绝缘基态。界面水与$6\times 6$ 表面的上层建筑 $\mathrm{1个}Ť\text{-}{钽}_2$，水岛下的电荷顺序可以直接在使用负偏置电压拍摄的STM地形图中成像。与原来相比$\sqrt{13}\times \sqrt{13}$ 收取订单 $\mathrm{1个}Ť\text{-}{钽}_2$，水岛下的电荷顺序变得明显混乱和密集。一种$\mathsf{V}$形的间隙状特征出现在被水覆盖的区域 $\mathrm{1个}Ť\text{-}{钽}_2$，这可能是由于界面水的介电常数提高所致，该介电常数降低了短程库仑排斥力并导致莫特间隙塌陷。我们的观察为微观地理解界面水与相关的物质量子态之间的相互作用开辟了道路。