Atomic and Electronic Structures of WTe2 Probed by High Resolution Electron Microscopy and ab Initio Calculations,The Journal of Physical Chemistry C

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Atomic and Electronic Structures of WTe2 Probed by High Resolution Electron Microscopy and ab Initio Calculations
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2016-04-13 00:00:00 , DOI: 10.1021/acs.jpcc.6b01044
Ning Lu ₁ , Chenxi Zhang ₁ , Chia-Hui Lee , Juan Pablo Oviedo ₁ , Minh An T. Nguyen , Xin Peng ₁ , Robert M. Wallace ₁ , Thomas E. Mallouk , Joshua A. Robinson , Jinguo Wang ₁ , Kyeongjae Cho ₁ , Moon J. Kim ₁

Affiliation

Transition metal dichalcogenides (TMDs) are a class of two-dimensional (2D) materials that have attracted growing interest because of their unique electronic and optical properties. Under ambient conditions, most TMDs generally exhibit 2H or 1T structures. Unlike other group VIb TMDs, bulk crystals and powders of WTe₂ exist in a distorted 1T structure (Td) at room temperature and have semimetallic properties. There is so far a lack of direct atom-by-atom visualization, limiting our understanding of this distorted 2D layered material system. We present herein atomic resolution images of Td structured WTe₂. The Td structure can be distinguished in the three major orientations along the [100], [010], and [001] zone axes. Subtle structural distortions are detected by atomic resolution imaging, which match well with the optimized structure relaxed by ab initio calculations. The calculations also showed that both crystal field splitting and charge density wave (CDW) interactions contribute to the stabilization of WTe₂. However, the CDW interaction dominates and leads the Td-WTe₂ to be the most stable structure. The combined atomic resolution STEM and ab initio study on WTe₂ provided the basis for understanding the correlations between atomic structure and electronic properties in Td structured TMD materials.

中文翻译：

高分辨率电子显微镜探测WTe _2的原子和电子结构并从头算

过渡金属二硫化碳（TMD）是一类二维（2D）材料，由于其独特的电子和光学特性，引起了越来越多的关注。在环境条件下，大多数TMD通常显示2H或1T结构。与其他VIb组TMD不同，WTe _2的块状晶体和粉末在室温下以扭曲的1T结构（Td）存在，并具有半金属性能。到目前为止，缺少直接的逐个原子可视化，这限制了我们对这种变形的2D分层材料系统的理解。我们在此介绍Td结构化WTe _2的原子分辨率图像。在沿着[100]，[010]和[001]区域轴的三个主要方向上，可以区分Td结构。通过原子分辨率成像可以检测到细微的结构变形，这与通过从头算计算得到放松的优化结构非常匹配。计算还表明，晶体场分裂和电荷密度波（CDW）相互作用均有助于WTe ₂的稳定化。但是，CDW相互作用起主导作用，并导致Td-WTe ₂成为最稳定的结构。结合了WTE _2的原子分辨率STEM和从头算研究，为理解Td结构TMD材料中原子结构与电子性能之间的相关性提供了基础。

更新日期：2016-04-13

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