Enhanced Ising Superconductivity and Emergent Ferromagnetism Coexisting in Bimolecule-Intercalated Bulk TaS₂.

Abstract

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 TaS₂, with the exotic phenomenon of quantum Griffiths singularity. It is first shown that the neighboring TaS₂ layers are separated by 14.7 Å, indicating vertical stacking of the TBAC and DMF molecules. Such a record-large interlayer spacing renders each TaS₂ 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 TaS₂ (≈0.8 K), and again approaches that of monolayer TaS₂ (≈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-TaS₂ as a fertile platform for exploration of rich physical phenomena with significant technological potentials in superconducting spintronics.