论文标题
Ising超导体nbse $ _ {2} $中的电子音波耦合和自旋波动
Electron-phonon coupling and spin fluctuations in the Ising superconductor NbSe$_{2}$
论文作者
论文摘要
在NBSE $ _ {2} $和类似材料中实验观察到的超导性，引起了极大的兴趣。最近，人们注意到自旋波动（SF）在这种现象中发挥的可能作用，此外，除了主要的电子波偶联（EPC）之外，还引起了人们的注意。讨论了主要的三脑状态的可能性，并导致了可行的单线 - 三角形Leggett振荡的猜想。但是，这些假设尚未进行定量测试。在本文中，我们报告了EPC的第一个原理计算，并估算了与SF的耦合，包括全部动量依赖性。我们发现：（1）EPC强烈各向异性，主要来自K-K的散射，因此即使是激发态，也排除了三胞胎对称性； （2）SF基本上削弱了超导性，但各向异性仍然如上所述；并且，（3）我们确实找到了Leggett模式的可能性，而不是在单曲线中，而是在$ s _ {++} $ - $ s_ \ pm $ channel中。
Ising superconductivity, observed experimentally in NbSe$_{2}$ and similar materials, has generated tremendous interest. Recently, attention was called to the possible role that spin fluctuations (SF) play in this phenomenon, in addition to the dominant electron-phonon coupling (EPC); the possibility of a predominantly-triplet state was discussed and led to a conjecture of viable singlet-triplet Leggett oscillations. However, these hypotheses have not been put to a quantitative test. In this paper, we report first principle calculations of the EPC and also estimate coupling with SF, including full momentum dependence. We find that: (1) EPC is strongly anisotropic, largely coming from the K-K' scattering, and therefore excludes triplet symmetry even as an excited state; (2) superconductivity is substantially weakened by SF, but anisotropy remains as above; and, (3) we do find the possibility of a Leggett mode, not in a singlet-triplet but in an $s_{++}$ - $s_\pm$ channel.
