Direct observation of anisotropic Cooper pairing in kagome superconductor CsV3Sb5

• DOI: 10.48550/arxiv.2404.18472
• Publication Date: 2024-04-29
• Authors: Akifumi Mine; Yigui Zhong; Jinjin Liu; Takeshi Suzuki; Sahand Najafzadeh; Takumi Uchiyama; Jia‐Xin Yin; Xianxin Wu; Xun Shi; Zhiwei Wang; Yugui Yao; Kozo Okazaki
• Keywords: Cooper pair

In the recently discovered kagome superconductor AV3Sb5 (A = K, Rb, and Cs), superconductivity is intertwined with an unconventional charge density wave order. Its pairing symmetry remains elusive owing to lack of direct measurement superconducting gap in momentum space. this letter, utilizing laser-based ultra-high-resolution low-temperature angle-resolved photoemission spectroscopy, we observe anisotropic Cooper CsV3Sb5. We detect a highly structure anisotropy over 80% maximum along V-V bond direction on Fermi surface originated from 3d-orbital electrons V lattice. It stark contrast isotropic other that occupied by Sb 5p-orbital electrons. Our observation pristine CsV3Sb5 fundamental for understanding orders ground state superconductors.