3D Ising Superconductivity in As-Grown Sn Intercalated TaSe₂ Crystal

2D Ising superconductivity emerges in noncentrosymmetric 2D materials, differing from conventional 2D/3D superconductivity. Here, we report the synthesis of a new polymorph of intercalated layered materials, where two layers of Sn are intercalated in between every two layers of TaSe₂ (2Sn-2TaSe₂), in contrast to the commonly observed single-layer intercalation. Remarkably, the as-grown 2Sn-2TaSe₂ single crystals possess a high quality of crystallinity and showcase 3D Ising superconductivity. Transport measurements and theoretical calculations show that the 2Sn-2TaSe₂ having C point group symmetry induces formation of Ising pairs, which intriguingly exhibits, on one hand, an in-plane upper critical field surpassing the Pauli limit by a factor of 2.6 like a 2D Ising superconductor but, on the other hand, a temperature- and field-dependent conductivity characteristic of conventional 3D superconductivity. Our findings demonstrate the persistent 2D Ising pairing in 3D, paving the way for exploring dimensional physical behaviors by intercalating layered materials.