Superconductivity in Li-intercalated 1T-SnSe2 driven by electric-field gating

Abstract

Creating carrier reservoirs in layered compounds can effectively tune the carrier density, which often induces a variety of emergent properties. Based on solid-ion-conductor gating technique, we successfully induce superconductivity of 4.8 K in ultrathin Li-intercalated SnSe2 samples. The Li+ ions are driven in between interspacing of SnSe2 layers and form a single reservoir layer to provide electrons. In addition, a dome-like T c is found through substituting of S for Se, where the optimal T c is 6.2 K for SnSe1.8S0.2. Density functional theory calculations confirm that the intercalated LiSnSe2 is thermodynamically favorable, where the intercalation of Li expands the interlayer spacing by 10% and increases the carrier density by two orders of magnitude. Meanwhile the calculated results reveal that the enhanced electron-phonon interaction due to softened phonon determines the occurrence of superconductivity. Our results demonstrate that this strategy is very effective to explore superconductors in layered materials with narrow bandgap.

arXiv commentAccepted by Physical Review Materials

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• Photon drag of superconducting fluctuations in 2D systems
• Majorana corner modes in unconventional monolayers of the 1T-PtSe2 family
• Reversible Tuning of Superconductivity in Ion-Gated NbN Ultrathin Films by Self-Encapsulation with a High-$\kappa$ Dielectric Layer
• Interfacial superconductivity in the type-III heterostructure SnSe${}_2$/PtTe${}_2$