AI 中文总结
研究1T-TaSe₂表面绝缘行为，通过密度泛函理论计算表明其绝缘表面源于CDW堆叠重构，块状为单层CDW堆叠支持金属传输，表面倾向双层堆叠打开约0.4 eV能隙，确立CDW表面重构为控制其表面电子结构机制并解释金属与绝缘域共存。
AI 中文摘要
块状1T-TaSe₂是金属性的，但其表面始终表现出绝缘能隙，这种二分法长期以来归因于由增强的电子关联驱动的表面莫特绝缘体。本文通过密度泛函理论计算表明，这种绝缘表面源自电荷密度波（CDW）堆叠重构。块状稳定支持金属传输的单层CDW堆叠，而表面在能量上更倾向于双层堆叠，其中Ta 5dₜ₂轨道的层间杂化打开了约0.4 eV的能隙，这是一种无需在位库仑排斥的带绝缘体。这种重构是两层到八层平板厚度的热力学基态，计算出的表面态密度定量地再现了绝缘和金属域的扫描隧道光谱。我们的结果确立了CDW表面重构而非莫特物理作为控制1T-TaSe₂表面电子结构的机制，并为实验观察到的金属和绝缘域的共存提供了统一解释。
英文摘要
Bulk 1T-TaSe$_2$ is metallic, yet its surface consistently exhibits an insulating gap -- a dichotomy long attributed to a surface Mott insulator driven by enhanced electron correlations. Using density functional theory calculations, we show that this insulating surface instead originates from a charge-density-wave (CDW) stacking reconstruction. Whereas the bulk stabilizes a single-layer CDW stacking that supports metallic transport, the surface energetically favors a bilayer stacking, in which interlayer hybridization of Ta $5d_{z^2}$ orbitals opens a $\sim$0.4 eV gap -- a band insulator requiring no on-site Coulomb repulsion. This reconstruction is the thermodynamic ground state for slab thicknesses from two to eight layers, and the calculated surface density of states quantitatively reproduces scanning tunneling spectra of both insulating and metallic domains. CDW surface reconstruction, rather than Mott physics, thus governs the surface electronic structure of 1T-TaSe$_2$, providing a unified explanation for the observed coexistence of metallic and insulating domains.
Comments21 pages, 4 figures
Journal refNano Lett. (2026)
DOI：10.1021/acs.nanolett.6c02230
