A New Paradigm to Achieve Time-Reversal Symmetry Breaking Superconductivity with Chiral Molecule Intercalation

Time-reversal symmetry breaking (TRSB) superconductivity arises with magnetic ordering or certain types of low-symmetry superconducting pairing order parameters. TRSB superconductors often indicate topologically non-trivial bound states under particle-hole symmetry, making them a dynamic field for exploring methods to encode quantum information with topological protection. In this work, we demonstrate a novel route to achieve TRSB superconductors by inserting chiral molecules into the interlayer van der Waals gap of otherwise s-wave superconductor tantalum disulfide. The spontaneous TRSB in this system is evidenced by the observation of a field-free superconducting diode effect, which violates both inversion symmetry and time-reversal symmetry. The superconducting diode polarity remains unchanged under different field cooling procedures, suggesting that the TRS breaking is likely due to a TRSB gap function rather than unintentional magnetic impurities. An exceptionally large in-plane upper critical field 9 times above the Pauli paramagnetic limit is observed, indicating a unconventional pairing mechanism beyond the Bardeen–Cooper–Schrieffer (BCS) theory. The topological nature is further implied by a π phase shift in Little-Parks oscillations in a nano-ring structured device. This work introduces a new paradigm for investigating TRSB superconductivity and chiral-related physics by incorporating organic molecular chirality into 2D solid-state systems.