Pressure-induced Ising superconductivity in organic-intercalated 1T-TaS2.

Layered transition metal dichalcogenides host a rich landscape of correlated electronic phases that are profoundly sensitive to interlayer coupling. Although both thinning and pressure have been individually used to tune these properties, the high-pressure behavior of low-dimensional systems remains largely unexplored. Here, we propose a synergistic tuning strategy by combination of organic cation intercalation and pressure to simulate the properties of low-dimensional materials under pressure. We show that intercalating cetyltrimethylammonium cations into the bulk 1T-TaS2 significantly weakens the interlayer coupling and leads to an effective reduction in dimensionality. Moreover, the intercalated sample exhibits distinct features under high pressure as compared with non-intercalated one. The superconductivity in the intercalated sample is induced accompanied by a complete suppression of nearly commensurate CDW order, differing from the melting of commensurate state in the non-intercalated case. Upon further compression up to 58.1 GPa, the superconductivity displays a dome-shaped evolution, also without showing re-enhancement that presented in the non-intercalated sample. More strikingly, the superconductivity in the intercalated 1T-TaS2 displays signatures of Ising superconductivity, with its in-plane upper critical field exceeding twice the Pauli paramagnetic limit. Our findings not only provide a powerful route for tuning the collective electronic states but also open up possibilities in searching for emergent phenomena in low-dimensional materials.