Emergent superconductivity in two-dimensional NiTe$_2$ crystals

TL;DR

This study predicts that monolayer NiTe₂ is an intrinsic superconductor with a transition temperature around 5.7 K, and bilayer NiTe₂ intercalated with lithium exhibits two-gap superconductivity with a higher transition temperature of 11.3 K, highlighting potential for 2D superconducting applications.

Contribution

First theoretical prediction of intrinsic superconductivity in monolayer NiTe₂ and discovery of two-gap superconductivity in lithium-intercalated bilayer NiTe₂.

Findings

Monolayer NiTe₂ is predicted to be an intrinsic superconductor at ~5.7 K.

Lithium-intercalated bilayer NiTe₂ shows two-gap superconductivity at ~11.3 K.

Superconductivity in these materials is substrate-independent and tunable.

Abstract

Despite growing interest in them, highly crystalline two-dimensional superconductors derived from exfoliated layered materials are few. Employing the anisotropic Migdal-Eliashberg formalism based on {\it ab initio} calculations, we find monolayer NiTe$_{2}$ to be an intrinsic superconductor with a $T_{\text c}\sim$5.7~K, although the bulk crystal is not known to superconduct. Remarkably, bilayer NiTe$_{2}$ intercalated with lithium is found to display two-gap superconductivity with a critical temperature $T_{\text{c}}\sim 11.3$~K and superconducting gap of $\sim$3.1~meV, arising from a synergy of electronic and phononic effects. The comparatively high $T_\text{c}$, substrate independence and proximity tunability will make these superconductors ideal platforms for exploring intriguing correlation effects and quantum criticality associated two-dimensional superconductivity.