The nature of the superconducting pairing state in the pristine phase of a compressed kagome metal CsV3Sb5 under pressure is studied by the Migdal-Eliashberg formalism and density-functional theory calculations. We find that the superconducting gap distribution driven by electron-phonon coupling is nodeless and anisotropic. It is revealed that the hybridized V 3d and Sb 5p orbitals are strongly coupled to the V-V bond-stretching and V-Sb bond-bending phonon modes, giving rise to a wide spread of superconducting gap depending on its associated Fermi-surface sheets and momentum. Specifically, the superconducting gaps associated with V 3dxy,x2−y2,z2 and 3dxz,yz orbitals are larger in their average magnitude and more widely spread compared to that associated with the Sb 5pz orbital. Our findings demonstrate that the superconductivity of compressed CsV3Sb5 can be explained by the anisotropic multiband pairing mechanism with conventional phonon-mediated s-wave symmetry, evidenced by recent experimental observations under pressure as well as at ambient pressure.
@article{arxiv.2303.10080,
title = {Phonon-Mediated ${\bf S}$-Wave Superconductivity in the Kagome Metal CsV$_3$Sb$_5$ under Pressure},
author = {Chongze Wang and Jia Yu and Zhenyu Zhang and Jun-Hyung Cho},
journal= {arXiv preprint arXiv:2303.10080},
year = {2023}
}