Investigating Electron-Phonon Coupling in Kagome Superconductors AV₃Sb₅ (A=K,Rb,Cs) by ARPES

The AV₃Sb₅ (A=K,Rb,Cs) compounds, with their V-based kagome lattice motif, have garnered significant interest owing to their nontrivial band topology and intriguing phase diagram, characterized by time-reversal-symmetry-breaking charge density waves as well as multiple superconducting phases, some of which may be unconventional. In order to fully understand these phases, it is essential to understand the underlying many-body interactions, one of the most important of which is the electron-phonon coupling.

Angle-resolved photoemission spectroscopy (ARPES) provides direct access to the one-particle spectral function, offering a powerful avenue to investigate the low-energy many-body interactions in a system. Leveraging this capability, we extract the single-particle self-energy, which encodes the coupling between electrons and bosonic modes such as phonons. Through a careful analysis of this quantity, we provide important evidence towards the origin of the charge density wave and superconducting phases in this material class.