Possible superconducting order parameter symmetries in multi-orbital kagome metals

Kagome metals, particularly the AV₃Sb₅ (A = K, Rb, Cs) family, have attracted considerable attention for their potential to host various exotic quantum phases, including loop current order and unconventional superconductivity [1]. These materials exhibit Van Hove singularities near the Fermi energy, which significantly enhance electronic correlations and lead to rich phase diagrams. While previous theoretical studies primarily relied on single-orbital models [2], realistic Kagome metals possess multiple Van Hove singularities, necessitating a multi-orbital perspective for comprehensive understanding [3]. In this study, we investigate the effects of multi-orbital interactions on superconductivity in Kagome metals. Through parquet renormalization group analysis [4], we examine potential superconducting order parameters and leading instabilities. We present a phase diagram as a function of interaction parameters and discuss the implications for multi-orbital Kagome metallic systems.

[1] S. D. Wilson and B. R. Ortiz, AV₃Sb₅ kagome superconductors. Nat. Rev. Mater. 9, 420–432 (2024).

[2] Takamori Park, Mengxing Ye, and Leon Balents, Electronic instabilities of kagome metals: Saddle points and Landau theory Phys. Rev. B 104, 035142 (2021).

[3] Mingu Kang et al., Twofold van Hove singularity and origin of charge order in topological kagome superconductor. CsV₃Sb₅ Nat. Phys. 18, 301 (2022).

[4] Rahul Nandkishore, L. S. Levitov, and A. V. Chubukov, Chiral superconductivity from repulsive interactions in doped graphene. Nat. Phys. 8, 158 (2012); Yu-Ping Lin and Rahul M. Nandkishore, Parquet renormalization group analysis of weak-coupling instabilities with multiple high-order Van Hove points inside the Brillouin zone. Phys. Rev. B 102, 245122 (2020).