Yung-Ting Lee Po-Tuan Chen Zheng-Hong Li Jyun-Yu Wu Chia-Nung Kuo Chin Shan Lue Chien-Te Wu Chien-Cheng Kuo Cheng-Tien Chiang Taisuke Ozaki Chun-Liang Lin* Chi-Cheng Lee* Hung-Chung Hsueh* Ming-Chiang Chung* ACS Materials Lett. 2024, 6, 7, 2941–2947
This research delves into the controversial role of Fermi surface nesting in the formation of charge density waves (CDWs) in 2H-NbSe2 due to Peierls instability.
By analyzing characteristics derived from scanning tunneling microscopy (STM) images and first-principles simulations, four distinct atomic structures of NbSe2 were identified. The calculations revealed an energetically favorable commensurate phase atomic structure. This structure aligns with Peierls’ description, exhibiting a fully opened electronic band gap at the CDW Brillouin zone boundary. This opening leads to a noticeable decrease in both the density of states and scanning tunneling spectra at the Fermi level.
Further investigation into the electronic susceptibility and phonon instability indicates that this commensurate phase’s Fermi surface nesting is triggered by the combination of two nesting vectors. If only a single nesting vector were involved, it would result in a “stripe phase.”
This comprehensive study concludes that the commensurate phase structure of NbSe2 can be classified as a CDW driven by Peierls instability in a two-dimensional system.