Distinctive momentum dependent charge-density-wave gap observed in CsV${}_3$Sb${}_5$ superconductor with topological Kagome lattice

Abstract

CsV${}_3$Sb${}_5$ is a newly discovered Kagome superconductor that attracts great interest due to its topological nontrivial band structure and the coexistence of superconductivity and charge-density-wave (CDW) with many exotic properties. Here, we report the detailed characterization of the CDW gap in high-quality CsV${}_3$Sb${}_5$ single crystals using high-resolution angle-resolved photoemission spectroscopy. We find that the CDW gap is strongly momentum dependent. While gapped around the $M$ point, the electronic states remain gapless around the $\Gamma$ point and along the $\Gamma$-$K$ direction. Such momentum dependence indicates that the CDW is driven by the scattering of electrons between neighboring $M$ points, where the band structure hosts multiple saddle points and the density of state diverges near the Fermi level. Our observations of the partially gapped Fermi surface and strongly momentum-dependent CDW gap not only provide a foundation for uncovering the mechanism of CDW in CsV${}_3$Sb${}_5$, but also shed light on the understanding of how the CDW coexists with superconductivity in this topological Kagome superconductor.

10 pages, 4 figures

Cited by in corpus (2)

• Evidence of a hidden flux phase in the topological kagome metal CsV${}_3$Sb${}_5$
• Carrier Injection and Manipulation of Charge-Density Wave in Kagome Superconductor CsV3Sb5