Quasi-two-dimensional superconductivity in SnSe2 via organic ion intercalation

In this work, two organic-ion-intercalated $\mathrm{Sn}{\mathrm{Se}}_{2}$ superconductors, ${(\mathrm{TBA})}_{x}\mathrm{Sn}{\mathrm{Se}}_{2}$ $({T}_{c}\ensuremath{\sim}6.4\phantom{\rule{0.16em}{0ex}}\mathrm{K})$ and ${(\mathrm{CTA})}_{x}\mathrm{Sn}{\mathrm{Se}}_{2}$ $({T}_{c}\ensuremath{\sim}7.1\phantom{\rule{0.16em}{0ex}}\mathrm{K})$, are synthesized by an electrochemical intercalation method. Via the intercalation of organic ions, the interlayer distance is dramatically enlarged from 6.12 \AA{} of pristine $\mathrm{Sn}{\mathrm{Se}}_{2}$ to 18.62 and 14.74 \AA{} for ${(\mathrm{TBA})}_{x}\mathrm{Sn}{\mathrm{Se}}_{2}$ and ${(\mathrm{CTA})}_{x}\mathrm{Sn}{\mathrm{Se}}_{2}$, respectively. Bulk magnetic susceptibility measurements suggest that both superconductors exhibit a strong anisotropic superconducting shielding effect below ${T}_{c}$. Further measurements of resistivity, I-V characteristic curves, and magnetoresistance reveal a quasi-two-dimensional (2D) superconductivity in ${(\mathrm{CTA})}_{x}\mathrm{Sn}{\mathrm{Se}}_{2}$. The present work suggests that the organic-ion-intercalation method can induce quasi-2D superconductivity in $\mathrm{Sn}{\mathrm{Se}}_{2}$ layers and provides a simple and practical strategy to explore 2D superconductivity as well as other 2D phenomena in layered materials.