Unusual charge density wave introduced by the Janus structure in monolayer vanadium dichalcogenides
Ziqiang Xu, Yan Shao, Chun Huang, Chao Zhu, Genyu Hu, Shihao Hu, Zhilin Li, Xiaoyu Hao, Yanhui Hou, Teng Zhang, Liwei Liu, Jinan Shi, Chen Liu, Jiaou Wang, Wu Zhou, Jiadong Zhou, Wei Ji, Yeliang Wang, Chendong Zhang, Jingsi Qiao, Hong‐Jun Gao, Xu Wu
Abstract
As a fundamental structural feature, the symmetry of materials determines the exotic quantum properties in transition metal dichalcogenides (TMDs) with charge density waves (CDWs). The Janus structure, an artificially constructed lattice, provides an opportunity to tune the electronic structures and their associated behavior, such as CDW states. However, limited by the difficulties in atomic-level fabrication and material stability, the experimental visualization of the CDW states in two-dimensional (2D) TMDs with Janus structure is still rare. Here, using surface selenization of VTe 2 , we fabricated monolayer Janus VTeSe. With scanning tunneling microscopy, we observed and characterized an unusual <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:msqrt> <mml:mn>13</mml:mn> </mml:msqrt> <mml:mo>×</mml:mo> <mml:msqrt> <mml:mn>13</mml:mn> </mml:msqrt> </mml:mrow> </mml:math> CDW state with threefold rotational symmetry breaking. Combined with theoretical calculations, we find that this CDW state can be attributed to the magnetic-involved charge modulation in the Janus VTeSe, rather than the conventional electron-phonon coupling. Our findings provide a promising platform for studying the CDW states and artificially tuning the electronic properties of the 2D TMDs toward the related fundamental and applied studies.