Gapless excitations inside the fully gapped kagome superconductors AV$_3$Sb$_5

• Main Authors: Gu, Yuhao, Zhang, Yi, Feng, Xilin, Jiang, Kun, Hu, Jiangping
• Format: Journal Article
• Language: English
• Published: 10-08-2021
• Subjects: Physics - Superconductivity
• DOI: 10.48550/arxiv.2108.04703

Phys. Rev. B 105, L100502 (2022) The superconducting gap structures in the transition-metal-based kagome metal
AV$_3$Sb$_5$ (A=K,Rb,Cs), the first family of quasi-two-dimensional kagome
superconductors, remain elusive as there is strong experimental evidence for
both nodal and nodaless gap structures. Here we show that the dichotomy can be
resolved because of the coexistence of time-reversal symmetry breaking with a
conventional fully gapped superconductivity. The symmetry protects the edge
states which arise on the domains of the lattice symmetry breaking order to
remain gapless in proximity to a conventional pairing. We demonstrate this
result in a four-band tight-binding model using the V $d_{X^2-Y^2}$-like and
the in-plane Sb $p_z$-like Wannier functions that can faithfully capture the
main feature of the materials near the Fermi level.