原子级薄层1$T$-TaS$_2$中强增强的电荷密度波与关联绝缘态
Strongly Enhanced Charge-Density Waves and Correlated Insulating State in Atomically Thin 1$T$-TaS$_2$
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中文总结 AI 辅助
研究原子级薄层1$T$-TaS$_2$的厚度依赖CDW相变，发现薄层CDW增强源于库仑相互作用增强，为二维CDW体系关联相工程提供方向。
中文摘要 AI 辅助
我们利用变温拉曼光谱和电输运研究1$T$-TaS$_2$中厚度依赖的电荷密度波（CDW）相变。拉曼测量显示，非公度、近公度和公度CDW相持续存在至单层极限。随厚度减小，相变温度升高，同时面电阻上升数个数量级，载流子定域长度急剧缩短。单层中唯一不存在一阶迟滞的CCDW-NCCDW相变。计算表明，薄层中增强的CDW源于面外屏蔽减弱导致的库仑相互作用增强，尤其非局域分量。这些发现凸显电子关联、电声相互作用与层间耦合在调控原子级薄层1$T$-TaS$_2$基态与相变动力学中的协同作用，为二维CDW体系中关联相的工程化开辟路径。
英文摘要
We investigate thickness-dependent charge-density-wave (CDW) transitions in 1$T$-TaS$_2$ using temperature-dependent Raman spectroscopy and electrical transport. Raman measurements show that the incommensurate, nearly commensurate, and commensurate CDW phases persist down to the monolayer limit. As the thickness is reduced, the transition temperatures increase, accompanied by an orders-of-magnitude rise in sheet resistance and a sharp reduction in the carrier localization length. The first-order hysteretic CCDW-NCCDW transition is uniquely absent in the monolayer. Calculations suggest that the enhanced CDW in thin layers originates from strengthened Coulomb interactions due to reduced out-of-plane screening, particularly in the nonlocal component. These findings highlight the cooperative roles of electron correlation, electron-phonon interaction, and interlayer coupling in shaping the ground state and transition dynamics of atomically thin 1$T$-TaS$_2$, opening pathways for engineering correlated phases in two-dimensional CDW systems.
