Transport phenomena in time-reversal symmetry-breaking Kagome superconductors

Recent studies have found that all three materials within the vanadium-based Kagome superconductors (<i>A</i>V₃Sb₅, <i>A</i> = K, Cs, Rb) exhibit time-reversal symmetry-breaking behaviors in the superconducting states. Among the three, the Josephson junctions structured Nb/K_1–<i>x</i>V₃Sb₅/Nb and RbV₃Sb₅ show magnetic hysteresis below the superconducting transition temperature. In CsV₃Sb₅, there exists a zero-field superconducting diode effect, meaning the magnitude of the positive and negative superconducting critical current are different. We first discuss the similarities and differences among the three above-mentioned experiments. Then, we discuss the possible mechanisms responsible for the unconventional superconducting transport phenomena: such as chiral superconducting order parameter (d+id or p+ip), and chiral pair density waves arising from the coupling of the charge density waves and conventional superconducting states.