Nematic and chiral superconductivity emerging within the loop-current phase in kagome metals

Abstract

Abstract The kagome metals A V 3 Sb 5 ( A  = Cs, Rb, K) host multiple symmetry-breaking phases, including charge-density-wave and loop-current orders, and exhibit highly exotic superconductivity with pronounced nematicity and chirality. Remarkably, even dilute impurities transform this exotic superconducting state into an isotropic s -wave state. These observations pose a challenge to existing theoretical scenarios. We show that loop-current order induces nematic chiral d -wave superconductivity in kagome metals. The loop-current-induced orbital magnetization (OM) stabilizes one chiral superconducting channels. This OM-chirality coupling mechanism is generic and applies to pairing driven by either attractive or repulsive interactions. Furthermore, coexisting loop-current and bond orders give rise to pronounced nematic chiral superconductivity even for an almost C 6 -symmetric Fermi surface. For attractive pairing, dilute impurities suppress the chiral state and restore a conventional s -wave phase, as observed experimentally. The theory further predicts a robust 2 × 2 pair-density modulation. This study provides key insights into time-reversal-symmetry-breaking exotic superconductivity in kagome metals.