标题： 弗里德尔振荡和单层NbSe$_2$中的手征超导性 显示英文标题

标题： Friedel oscillations and chiral superconductivity in monolayer NbSe$_2$

摘要： 1965年，Kohn和Luttinger提出了一种真正的电子机制来解释超导性。 尽管两个电子之间的原始静电相互作用是排斥的，在金属中电子-空穴涨落可以导致屏蔽库仑势的Friedel振荡。 当利用吸引区域时，电子之间的Cooper对就会出现。 在一些二维过渡金属二硫属化物中，主导配对机制的性质仍然存在争议。 专注于NbSe$_2$，我们表明，当考虑三重晶格上多个轨道的屏蔽效应时，可以通过库仑相互作用诱导超导性。 使用基于第一性原理的紧束缚参数化方法对相关低能d带进行评估，我们在一个包括布洛赫重叠和Umklapp过程的方案中微观地计算了屏蔽相互作用。 在实空间中，我们发现符号交替的长程Friedel振荡。 动量分辨的能隙方程在临界温度$T_c$附近预测了两个准简并的向列态，表明配对的非常规性质。 它们的复数线性组合，即具有p型对称性的手性能隙，提供了系统的基态。 我们预测在$T_c$以下有一个完全禁带的手性相，这与从单层NbSe$_2$的隧道谱测量中提取的谱函数一致。 显示英文摘要

摘要： In 1965 Kohn and Luttinger proposed a genuine electronic mechanism for superconductivity. Despite the bare electrostatic interaction between two electrons being repulsive, in a metal electron-hole fluctuations can give rise to Friedel oscillations of the screened Coulomb potential. Cooper pairing among the electrons then emerges when taking advantage of the attractive regions. The nature of the leading pairing mechanism in some two-dimensional transition metal dichalcogenides is still debated. Focusing on NbSe$_2$, we show that superconductivity can be induced by the Coulomb interaction when accounting for screening effects on the trigonal lattice with multiple orbitals. Using ab initio-based tight-binding parametrizations for the relevant low-energy d-bands, we evaluate the screened interaction microscopically, in a scheme that includes Bloch overlaps and Umklapp processes. In the direct space, we find long-range Friedel oscillations which alternate in sign. The momentum-resolved gap equations predict two quasi-degenerate nematic solutions near the critical temperature $T_c$, signaling the unconventional nature of the pairing. Their complex linear combination, i.e., a chiral gap with p-like symmetry, provides the ground state of the system. Our prediction of a fully gapped chiral phase well below $T_c$ is in agreement with the spectral function extracted from tunneling spectroscopy measurements of single-layer NbSe$_2$.