Direct Observation of One-Dimensional Peierls-type Charge Density Wave in Twin Boundaries of Monolayer MoTe 2

作者：Li Wang, Ying Wu, Yayun Yu, Ai-Xi Chen, Huifang Li, Wei Ren, Shuai Lu, Sunan Ding, Hui Yang, Qi‐Kun Xue, Fangsen Li, Guang Wang · 发表于：ACS Nano · 年份：2020 · DOI：10.1021/acsnano.0c02072 · 被引用次数：42 · 研究领域：2D Materials and Applications、Topological Materials and Phenomena、MXene and MAX Phase Materials

One-dimensional (1D) metallic mirror-twin boundaries (MTBs) in monolayer transition-metal dichalcogenides exhibit a periodic charge modulation and provide an ideal platform for exploring collective electron behavior in the confined system. The underlying mechanism of the charge modulation and how the electrons travel in 1D structures remain controversial. Here, for the first time, we observed atomic-scale structures of the charge distribution within one period in MTB of monolayer MoTe 2 by using scanning tunneling microscopy/spectroscopy. The coexisting apparent periodic lattice distortions and U-shaped energy gap clearly demonstrate a Peierls-type charge density wave (CDW). Equidistant quantized energy levels with varied periodicity are further discovered outside the CDW gap along the metallic MTB. Density functional theory calculations are in good agreement with the gapped electronic structures and reveal that they originate mainly from a Mo 4d orbital. Our work presents hallmark evidence of the 1D Peierls-type CDW on the metallic MTBs and offers opportunities to study the underlying physics of 1D charge modulation.