论文标题

Eliashberg理论用于自旋 - 裂变介导的超导性 - 应用于散装和单层FESE

Eliashberg theory for spin-fluctuations mediated superconductivity -- Application to bulk and monolayer FeSe

论文作者

Schrodi, Fabian, Aperis, Alex, Oppeneer, Peter M.

论文摘要

我们提出了一种新颖的方法,可将自旋和电荷波动嵌入超导性的各向异性,多频段和全频带埃利亚斯伯格治疗中。我们的分析框架基于随机相近似,可以自言自语计算相互作用中材料特定特征,更具体地说是超导状态。我们将这种方法应用于批量FESE作为基于铁的超导体的代表,并成功地求解了超导过渡温度$ T_C $,间隙对称性和间隙幅度。我们获得了$ T_C \约6 $ K,与实验一致($ T_C \ 8 $ K),以及其他与实验观察的良好一致的数量,从而支持了散装FE​​SE中的自旋波动介导的配对。相反,在Srtio $ _3 $上应用我们的单层FESE方法,我们发现完整的Eliashberg框架中的自旋波动给出了$ d $ - 波间隙,并带有$ t_c \ le 11 $ k,因此无法为实验性的高度温度提供一个关键温度的解释($ t_c \ of t_c \ of of t_c \ of 70 $ k)。因此,我们的结果将界面电子 - 音波耦合作为该系统中的主要库珀配对介质。

We present a novel method for embedding spin and charge fluctuations in an anisotropic, multi-band and full-bandwidth Eliashberg treatment of superconductivity. Our analytical framework, based on the random phase approximation, allows for a selfconsistent calculation of material specific characteristics in the interacting, and more specifically, the superconducting state. We apply this approach to bulk FeSe as representative for the iron-based superconductors and successfully solve for the superconducting transition temperature $T_c$, the gap symmetry and the gap magnitude. We obtain $T_c \approx 6$ K, consistent with experiment ($T_c \approx 8$ K), as well as other quantities in good agreement with experimental observations, thus supporting spin fluctuations mediated pairing in bulk FeSe. On the contrary, applying our approach to monolayer FeSe on SrTiO$_3$ we find that spin fluctuations within the full Eliashberg framework give a $d$-wave gap with $T_c\le 11$ K and therefore cannot provide an explanation for a critical temperature as high as observed experimentally ($T_c \approx 70$ K). Our results hence point towards interfacial electron-phonon coupling as the dominant Cooper pairing mediator in this system.

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