Two-dimensional superconductors exfoliated from layered materials harbor novel superconductivity and exotic correlated phases, often concomitantly, but their discovery has been few and far between. Employing the anisotropic Migdal-Eliashberg formalism based on ab initio calculations, we find monolayer ${\mathrm{NiTe}}_2$ 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 ${\mathrm{NiTe}}_2$ intercalated with lithium is found to display two-gap superconductivity with a critical temperature $T_{\text{c}}\sim 11.3$ K and a superconducting gap of $\sim 3.1$ meV, arising from a synergy of electronic and phononic effects. As monolayer and bilayer ${\mathrm{NiTe}}_2$ have been recently isolated experimentally, and lithium can be inserted into the bilayer via ionic liquid gating, 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.

中文翻译：

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二维NiTe2晶体中的新兴超导性

从层状材料剥落的二维超导体常常伴随着新颖的超导相和奇异的相关相，但是它们的发现却很少且相差甚远。利用从头算的各向异性Migdal-Eliashberg形式主义，我们发现单层${\mathrm{镍铁}}_2$ 成为内在的超导体 ${Ť}_{\text{C}}〜5.7$K，尽管不知道块状晶体超导。明显地，双层${\mathrm{镍铁}}_2$ 发现嵌入锂时在临界温度下显示出两个能隙的超导性 ${Ť}_{\text{C}}〜11.3$ K和超导间隙 $〜3.1$meV，来自电子和声子效应的协同作用。作为单层和双层${\mathrm{镍铁}}_2$ 最近已经通过实验分离出来，并且可以通过离子液体门将锂插入双层中，相对较高 ${Ť}_{\text{C}}$，基板独立性和接近可调性将使这些超导体成为探索有趣的关联效应和量子临界相关二维超导性的理想平台。