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arXiv 1707.04547cond-mat.supr-con
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强耦合多带超导体中的准粒子干涉

Quasiparticle interference in multiband superconductors with strong coupling

A. Dutt, A. A. Golubov, O. V. Dolgov, D. V. Efremov

摘要:

本文在玻恩近似下,基于强耦合Eliashberg方法,发展了多带超导体中准粒子干涉(QPI)的理论。在此理论框架下,我们研究了具有无节点s波序参量序参量的多带超导体中QPI响应函数的依赖性。我们特别注意了具有相同和相反的序参量符号的带之间的准粒子散射的差异。我们发现,在动量值接近两个带之间的动量转移,准粒子干涉响应函数的能量依赖性有三个奇异性。其中两个对应于间隙函数的值,第三个依赖于间隙和转移动量。我们认为,只有最小带隙附近的奇异性可以作为一个通用的工具来区分$s_{++}$和$s_{\pm}$序参量。在两种对称情况下,无论参数的变化如何,在较小间隙值附近的响应函数峰值的符号的鲁棒性是可以通过实验利用的有希望的特征。

英文摘要:

We develop a theory of the quasiparticle interference (QPI) in multiband superconductors based on strong-coupling Eliashberg approach within the Born approximation. In the framework of this theory, we study dependencies of the QPI response function in the multiband superconductors with nodeless s-wave superconductive order parameter. We pay a special attention to the difference of the quasiparticle scattering between the bands having the same and opposite signs of the order parameter. We show that, at the momentum values close to the momentum transfer between two bands, the energy dependence of the quasiparticle interference response function has three singularities. Two of these correspond to the values of the gap functions and the third one depends on both the gaps and the transfer momentum. We argue that only the singularity near the smallest band gap may be used as an universal tool to distinguish between $s_{++}$ and $s_{\pm}$ order parameters. The robustness of the sign of the response function peak near the smaller gap value, irrespective of the change in parameters, in both the symmetry cases is a promising feature that can be harnessed experimentally.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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