Dichotomy of charge density wave and superconductivity in monolayer <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>NbS</mml:mi> <mml:mn>2</mml:mn> </mml:msub> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>NbSe</mml:mi> <mml:mn>2</mml:mn> </mml:msub> </mml:math> : A view from fermiology

Summary

The interplay of charge-density wave (CDW) and superconductivity is a key issue in low-dimensional materials, whereas it has yet to be clarified even in simple two-dimensional materials such as monolayer transition-metal dichalcogenide. We fabricated a monolayer 1H-${\mathrm{NbS}}_{2}$ film on bilayer graphene/SiC(0001) by combining the molecular-beam epitaxy and topotactic chemical reaction, and investigated the electronic structure by angle-resolved photoemission spectroscopy in collaboration with first-principles calculation. We found that although the Fermi surface of monolayer 1H-${\mathrm{NbS}}_{2}$ consists of large hole pockets centered at the $\mathrm{\ensuremath{\Gamma}}$ and K points similarly to isostructural monolayer 1H-${\mathrm{NbSe}}_{2}$, the shape of the pocket at the K