Anisotropic band splitting in monolayer NbSe2: implications for superconductivity and charge density wave

Yuki Nakata, Katsuaki Sugawara, Satoru Ichinokura, Yoshinori Okada, Taro Hitosugi, Takashi Koretsune, Keiji Ueno, Shuji Hasegawa, Takashi Takahashi, Takafumi Sato

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)

Abstract

Realization of unconventional physical properties in two-dimensional (2D) transition-metal dichalcogenides (TMDs) is currently one of the key challenges in condensed-matter systems. However, the electronic properties of 2D TMDs remain largely unexplored compared to those of their bulk counterparts. Here, we report the fabrication of a high-quality monolayer NbSe2 film with a trigonal prismatic structure by molecular beam epitaxy, and the study of its electronic properties by scanning tunneling microscopy, angle-resolved photoemission spectroscopy, and electrical transport measurements, together with first-principles band-structure calculations. In addition to a charge density wave (CDW) with 3 × 3 periodicity and superconductivity below 1.5 K, we observed sizable (~0.1 eV) band splitting along the Γ-K cut in the Brillouin zone due to inversion symmetry breaking in the monolayer crystal. This splitting is highly anisotropic in k space, leading to a spin-split van-Hove singularity in the band structure. The present results suggest the importance of spin–orbit coupling and symmetry breaking for unconventional superconductivity and CDW properties in monolayer TMDs.

Original languageEnglish
Article number12
Journalnpj 2D Materials and Applications
Volume2
Issue number1
DOIs
Publication statusPublished - 2018 Dec 1

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanical Engineering
  • Mechanics of Materials
  • Condensed Matter Physics
  • Chemistry(all)

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