TY - JOUR
T1 - Anisotropic band splitting in monolayer NbSe2
T2 - implications for superconductivity and charge density wave
AU - Nakata, Yuki
AU - Sugawara, Katsuaki
AU - Ichinokura, Satoru
AU - Okada, Yoshinori
AU - Hitosugi, Taro
AU - Koretsune, Takashi
AU - Ueno, Keiji
AU - Hasegawa, Shuji
AU - Takahashi, Takashi
AU - Sato, Takafumi
N1 - Funding Information:
We thank N. Shimamura, Y. Umemoto, and S. Souma for their assistance in the ARPES measurements. This work was supported by JSPS KAKENHI Grants (JP25107003, JP15H05853, JP16H00924, JP25110010, JP25287079, and JP15H02105), Grant for Basic Science Research Projects from the Sumitomo Foundation, Science Research Projects from Iketani Science and Technology Foundation, the Program for Key Interdisciplinary Research, and World Premier International Research Center, Advanced Institute for Materials Research. Y.N. acknowledges support from GP-Spin at Tohoku University.
Publisher Copyright:
© 2018, The Author(s).
PY - 2018/12/1
Y1 - 2018/12/1
N2 - 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.
AB - 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.
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U2 - 10.1038/s41699-018-0057-3
DO - 10.1038/s41699-018-0057-3
M3 - Article
AN - SCOPUS:85059441367
VL - 2
JO - npj 2D Materials and Applications
JF - npj 2D Materials and Applications
SN - 2397-7132
IS - 1
M1 - 12
ER -