Multiple Energy Scales and Anisotropic Energy Gap in the Charge-Density-Wave Phase of Kagome Superconductor CsV3Sb5

Kosuke Nakayama; Yongkai Li; Takemi Kato; Min Liu; Zhiwei Wang; Takashi Takahashi; Yugui Yao; Takafumi Sato

doi:10.1103/physrevb.104.l161112

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arXiv · 2104.08042

Multiple Energy Scales and Anisotropic Energy Gap in the Charge-Density-Wave Phase of Kagome Superconductor CsV3Sb5

Kosuke Nakayama·Yongkai Li·Takemi Kato·Min Liu·Zhiwei Wang·Takashi Takahashi·Yugui Yao·Takafumi Sato

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Abstract

Kagome metals AV3Sb5 (A = K, Rb, and Cs) exhibit superconductivity at 0.9-2.5 K and charge-density wave (CDW) at 78-103 K. Key electronic states associated with the CDW and superconductivity remain elusive. Here, we investigate low-energy excitations of CsV3Sb5 by angle-resolved photoemission spectroscopy. We found an energy gap of 70-100 meV at the Dirac-crossing points of linearly dispersive bands, pointing to an importance of spin-orbit coupling. We also found a signature of strongly Fermi-surface and momentum-dependent CDW gap characterized by the larger energy gap of maximally 70 meV for a band forming a saddle point around the M point, the smaller (0-18 meV) gap for a band forming massive Dirac cones, and a zero gap at the Gamma-centered electron pocket. The observed highly anisotropic CDW gap which is enhanced around the M point signifies an importance of scattering channel connecting the saddle points, laying foundation for understanding the nature of CDW and superconductivity in AV3Sb5.

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Kosuke Nakayama, Yongkai Li, Takemi Kato, Min Liu, Zhiwei Wang, Takashi Takahashi, Yugui Yao, Takafumi Sato. 2021-04-16. Multiple Energy Scales and Anisotropic Energy Gap in the Charge-Density-Wave Phase of Kagome Superconductor CsV3Sb5. https://doi.org/10.1103/physrevb.104.l161112

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