Superconductivity in Electrochemically Intercalated R/S‑CTA-SnSe₂ by Using Chiral Piezoelectric Precursors

Molecule intercalation has shown distinct advantages in modulating the superconducting properties of 2D materials. Chiral molecule intercalation provides a strategy for tuning electronic properties, while this approach has been limited to a few 2D materials such as TaS₂ and TiS₂. Although extensive research on 2D SnSe₂ exists, chiral molecule intercalation in SnSe₂ remains unexplored. Herein, we report the first successful electrochemical intercalation of chiral CTA cations (CTA = 3-chloro-2-hydroxypropyltrimethylammonium) into SnSe₂ by using piezoelectric R/S-CTA-Cl with a large piezoelectric coefficient of approximately 24 pm/V as the precursors, leading to the formation of superconductors R/S-CTA-SnSe₂. Characterization techniques, including powder X-ray diffraction, Raman spectroscopy, and circular dichroism spectroscopy, confirm a significant lattice expansion in SnSe₂ and the successful intercalation of chiral CTA cations, while polar R/S-CTA-Cl does not endow R/S-CTA-SnSe₂ with piezoelectric/ferroelectric properties. Magnetic susceptibility and electrical transport measurements reveal that the intercalated R/S-CTA-SnSe₂ materials exhibit a superconducting transition at around 5 K. Notably, the distinct out-of-plane and in-plane upper critical magnetic fields demonstrate the 2D nature of the intercalated compounds. This work highlights an approach for designing and tailoring superconducting materials through chiral cation intercalation and opens avenues for further exploration of chiral effects in superconductors.