Enhanced Ising Superconductivity and Emergent Ferromagnetism Coexisting in Bimolecule-Intercalated Bulk TaS.

Superconductivity and ferromagnetism are mutually exclusive in most cases. Here the observation of Ising superconductivity and ferromagnetism coexisting is reported in a bimolecule (tetrabutylammonium chloride and dimethylformamide, or TBAC/DMF)-intercalated bulk TaS, with the exotic phenomenon of quantum Griffiths singularity. It is first shown that the neighboring TaS layers are separated by 14.7 Å, indicating vertical stacking of the TBAC and DMF molecules. Such a record-large interlayer spacing renders each TaS layer to be of exceptionally 2D nature in an otherwise 3D structure, as manifested by substantially enhanced Ising superconductivity with in-plane upper critical field five times the Pauli limit. The corresponding superconducting transition temperature is ≈2.7 K, more than tripled from that of pristine bulk TaS (≈0.8 K), and again approaches that of monolayer TaS (≈3 K). Strikingly, distinct ferromagnetism is observed below the superconducting temperature, and the ferromagnetic order persists all the way up to 365 K. These findings characterize TBAC/DMF-TaS as a fertile platform for exploration of rich physical phenomena with significant technological potentials in superconducting spintronics.