标题： 弗里德尔振荡和单层NbSe$_2$中的手性超导性 显示英文标题

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

摘要： 1965年，Kohn和Luttinger提出了超导性的真正电子机制。 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配对就会出现。 在一些二维过渡金属二硫化物中，主要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。 使用相关低能d带的第一性原理紧束缚参数化方法，我们在包括布洛赫重叠的方案中微观地评估了屏蔽相互作用。 在实空间中，我们发现符号交替的长程Friedel振荡，这是Kohn-Luttinger机制的关键。 动量分辨的能隙方程在临界温度Tc处预测了两个简并解，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。 我们对低于Tc的完全能隙手性相的预测与单层NbSe$_2$的隧道谱测量中提取的谱函数高度一致。 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 including Bloch overlaps. In the direct space, we find long-range Friedel oscillations alternating in sign, a key to the Kohn-Luttinger mechanism. The momentum-resolved gap equations predict two degenerate solutions at the critical temperature Tc, 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 Tc is in excellent agreement with the spectral function extracted from tunneling spectroscopy measurements of single-layer NbSe$_2$.