Time-reversal symmetry breaking superconductivity in chiral molecule intercalated TaS₂

Superconductors that violate time-reversal symmetry (TRS) are often associated with unconventional pairing mechanisms and topological superconductivity, and thus are intensively studied with the hope of harnessing the topological protection for quantum information processing. TRS breaking can arise by either incorporating magnetism into superconductivity or, more profoundly, by establishing chiral superconducting ordering parameters that intrinsically lack TRS. Here, we introduce a new route to induce chiral superconductivity by intercalating chiral molecules into otherwise s-wave two-dimensional van der Waals superconductor TaS₂. The spontaneous TRS breaking in chiral molecule-intercalated TaS₂ is evidenced by a field-free superconducting diode effect, which necessitates the absence of both TRS and inversion symmetry. The superconducting diode polarity remains unchanged under different field cooling procedures, suggesting that the TRS breaking is likely due to a chiral superconducting gap function rather than accidentally introduced magnetic impurities. Furthermore, an exceptionally large in-plane upper critical field that well exceeds the Pauli paramagnetic limit is observed, confirming the unconventional pairing mechanism beyond the Bardeen–Cooper–Schrieffer (BCS) theory. This work identifies a new paradigm for investigating chiral superconductivity and chiral-related physics by imbuing organic molecular chirality into 2D solid-state systems.