Phonon-mediated superconductivity in topological kagome metals Rh₃M₂S₂ (M = Pb, In, Tl)

Abstract Kagome materials possess intriguing properties and have attracted considerable interest. Inspired by the extensive research on kagome superconductors, here, we investigated the superconducting and topological properties of the trilayer kagome metals Rh 3 M 2 S 2 (M = Pb, In, Tl) via first-principles calculations. The calculated electron–phonon coupling parameters, which are mainly contributed by the in-plane electronic orbitals of Rh and the in-plane atomic vibrations of Rh and M (=Pb, In, Tl), indicate the shandite compounds Rh 3 M 2 S 2 (M = Pb, In, Tl) are weak superconductors. By solving the Allen-Dynes modified McMillan formula, the superconducting critical temperatures T c are estimated to be 1.03 (1.43), 2.31 (2.10) and 5.39 (6.88) K for M = Pb, In, Tl without (with) the spin-orbital coupling (SOC) effect, respectively. Based on the computation of topological invariants and surface states, Rh 3 M 2 S 2 (M = Pb, In, Tl) can be categorized as Z 2 topological metals when the SOCs are considered. This work unveils the superconductivity and nontrivial band topology of Rh 3 M 2 S 2 (M = Pb, In, Tl), and will facilitate the search for kagome superconductors in shandite-type materials.