Emergent superconductivity in two-dimensional NiTe${}_2$ crystals

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.