Single-water-dipole-layer-driven Reversible Charge Order Transition in 1<i>T</i>-TaS<sub>2</sub>.
basic_science · Level V
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- Record sourced from PubMed, PMID 33170704.
- Also identified by DOI 10.1021/acs.nanolett.0c03857.
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Abstract
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<i>T</i>-TaS<sub>2</sub> driven by a single water dipole layer. At low temperature, pristine 1<i>T</i>-TaS<sub>2</sub> is a prototypical CDW compound with <math xmlns="http://www.w3.org/1998/Math/MathML"><msqrt><mrow><mn>13</mn></mrow></msqrt></math> × <math xmlns="http://www.w3.org/1998/Math/MathML"><msqrt><mrow><mn>13</mn></mrow></msqrt></math> charge order. After growing a highly ordered water adlayer, a new charge order with 3 × 3 periodicity emerges on water-covered 1<i>T</i>-TaS<sub>2</sub>. After water desorption, the entire 1<i>T</i>-TaS<sub>2</sub> surface appears as localized <math xmlns="http://www.w3.org/1998/Math/MathML"><msqrt><mrow><mn>13</mn></mrow></msqrt></math> × <math xmlns="http://www.w3.org/1998/Math/MathML"><msqrt><mrow><mn>13</mn></mrow></msqrt></math> 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<i>T</i>-TaS<sub>2</sub>, which shifts the phonon softening mode and induces the <math xmlns="http://www.w3.org/1998/Math/MathML"><msqrt><mrow><mn>13</mn></mrow></msqrt></math> × <math xmlns="http://www.w3.org/1998/Math/MathML"><msqrt><mrow><mn>13</mn></mrow></msqrt></math> to 3 × 3 charge order transition. Our results pave the way for creating new collective quantum states of matter with a molecular dipole layer.