Degenerate Monolayer Ising Superconductors via Chiral‐Achiral Molecule Intercalation

ABSTRACT Engineering unconventional superconducting states is a central challenge in condensed matter physics. Molecule‐intercalated TaS 2 superlattices have recently been reported to host such states, yet their origin remains debated—underscoring the urgent need for controlled, device‐integrated studies. Here, we report that nanometer‐thick TaS 2 and NbSe 2 intercalated with chiral and achiral organic cations instead exhibit robust monolayer‐like Ising superconductivity, with no evidence of unconventional pairing. Using high‐quality superlattices integrated into devices, we disentangle the roles of interlayer coupling and charge transfer in shaping their superconducting behavior. In TaS 2 , intercalation induces interlayer decoupling regardless of molecular size or symmetry, yielding monolayer‐like Ising superconductivity. NbSe 2 instead retains quasi‐3D transport, with a gradual Ising enhancement and near‐monolayer behavior only at the largest interlayer spacing. Transport remains reciprocal across all superlattices, showing no measurable signatures of inversion‐symmetry breaking. The data are consistent with electronically detached monolayers with opposite spin‐split bands, coupled through thermal and tunneling processes. In this scenario, supported by DFT calculations, inversion symmetry is preserved. These findings establish molecular intercalation compounds as a robust, device‐ready, platform for engineering advanced superconducting superlattices.