Direct identification of Mott Hubbard band pattern beyond charge density wave superlattice in monolayer 1T-NbSe2

• Published in: Nature communications Vol. 12; no. 1; pp. 1978 - 7
• Main Authors: Liu, Liwei, Yang, Han, Huang, Yuting, Song, Xuan, Zhang, Quanzhen, Huang, Zeping, Hou, Yanhui, Chen, Yaoyao, Xu, Ziqiang, Zhang, Teng, Wu, Xu, Sun, Jiatao, Huang, Yuan, Zheng, Fawei, Li, Xianbin, Yao, Yugui, Gao, Hong-Jun, Wang, Yeliang
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 30.03.2021; Nature Publishing Group; Nature Portfolio
• Subjects: 119/118; 147/138; 639/301/357/1018; 639/766/119/1002; 639/766/119/995; Charge density waves; Humanities and Social Sciences; Insulators; Islands; Laboratories; Microscopy; Molecular beam epitaxy; Monolayers; multidisciplinary; Periodicity; Physics; Scanning tunneling microscopy; Science; Science (multidisciplinary); Spatial distribution; Spectroscopy; Spectrum analysis; Superlattices; Two dimensional materials
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-021-22233-w

Understanding Mott insulators and charge density waves (CDW) is critical for both fundamental physics and future device applications. However, the relationship between these two phenomena remains unclear, particularly in systems close to two-dimensional (2D) limit. In this study, we utilize scanning tunneling microscopy/spectroscopy to investigate monolayer 1T-NbSe 2 to elucidate the energy of the Mott upper Hubbard band (UHB), and reveal that the spin-polarized UHB is spatially distributed away from the dz 2 orbital at the center of the CDW unit. Moreover, the UHB shows a √3 × √3 R30° periodicity in addition to the typically observed CDW pattern. Furthermore, a pattern similar to the CDW order is visible deep in the Mott gap, exhibiting CDW without contribution of the Mott Hubbard band. Based on these findings in monolayer 1T-NbSe 2 , we provide novel insights into the relation between the correlated and collective electronic structures in monolayer 2D systems. The relationship between Mott state and charge density wave state in two dimensional materials remains unclear. Here, Liu et al. reveal spatial distribution of a Mott-Hubbard band in monolayer 1T-NbSe 2 forming a new periodic pattern in addition to the well-known CDW pattern.