Unconventional superconductivity in chiral molecule-TaS₂ hybrid superlattices.

Abstract

Chiral superconductors, a unique class of unconventional superconductors in which the complex superconducting order parameter winds clockwise or anticlockwise in the momentum space¹, represent a topologically non-trivial system with intrinsic time-reversal symmetry breaking (TRSB) and direct implications for topological quantum computing^2,3. Intrinsic chiral superconductors are extremely rare, with only a few arguable examples, including UTe₂, UPt₃ and Sr₂RuO₄ (refs. ^4-7). It has been suggested that chiral superconductivity may exist in non-centrosymmetric superconductors^8,9, although such non-centrosymmetry is uncommon in typical solid-state superconductors. Alternatively, chiral molecules with neither mirror nor inversion symmetry have been widely investigated. We suggest that an incorporation of chiral molecules into conventional superconductor lattices could introduce non-centrosymmetry and help realize chiral superconductivity¹⁰. Here we explore unconventional superconductivity in chiral molecule intercalated TaS₂ hybrid superlattices. Our studies reveal an exceptionally large in-plane upper critical field B_c2,|| well beyond the Pauli paramagnetic limit, a robust π-phase shift in Little-Parks measurements and a field-free superconducting diode effect (SDE). These experimental signatures of unconventional superconductivity suggest that the intriguing interplay between crystalline atomic layers and the self-assembled chiral molecular layers may lead to exotic topological materials. Our study highlights that the hybrid superlattices could lay a versatile path to artificial quantum materials by combining a vast library of layered crystals of rich physical properties with the nearly infinite variations of molecules of designable structural motifs and functional groups¹¹.