发表机构
Kent State University（肯特州立大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过自洽Keldysh--Nambu形式研究无序$d$-波超导体中Eliashberg效应，发现弹性杂质散射恢复吸收并激活配对增强，其频率窗口边界由准粒子再分布、加热与对破缺竞争决定，且上边界在接近临界温度时跨越最大能隙。
AI 中文摘要
我们研究了无序$d$-波超导体中外部电磁辐射对超导的激发——即Eliashberg效应。我们采用自洽的Keldysh--Nambu准经典形式，并加入非弹性弛豫项，在Born近似下处理弹性散射并保留完整的二阶杂质顶点，以计算配对幅度的静态修正。我们发现，干净的$d$-波超导体在任何频率下均无增强：在没有动量弛豫通道的情况下，空间均匀的驱动不产生吸收，仅导致对破缺。弹性杂质散射恢复了吸收，并随之激活了Eliashberg通道中的响应。我们发现配对幅度的增强仅限于一个有限的频率窗口、无序强度、非弹性散射速率和能隙幅度范围内。窗口的两个边界均随能隙标度，但由准粒子再分布、加热和对破缺之间的竞争决定，而非光谱特征。此外，与阈值固定在$2\Delta$的$s$-波情况相反，上边界并不固定在最大能隙上，并在系统接近临界温度时跨越该能隙。
英文摘要
We study the stimulation of superconductivity by an external electromagnetic radiation --- the Eliashberg effect --- in a disordered $d$-wave superconductor. We use the self-consistent Keldysh--Nambu quasiclassical formalism augmented by an inelastic relaxation term to compute the static correction to the pairing amplitude by treating elastic scattering within the Born approximation with the full second-order impurity vertex retained. We find that the clean $d$-wave superconductor shows no enhancement at any frequency: without a momentum relaxation channel a spatially uniform drive produces no absorption, only pair breaking. Elastic impurity scattering restores absorption and with it activates response in the Eliashberg channel. We find enhancement of the pairing amplitude which is confined to a bounded window in frequency, disorder strength, inelastic scattering rate and gap magnitude. Both edges of the window scale with the gap but are set by the competition between quasiparticle redistribution, heating and pair breaking rather than by a feature of the spectrum. Furthermore, in contrast to the $s$-wave when the threshold is pinned at $2Δ$, the upper edge is not pinned to the maximum gap and crosses it as the system approaches the critical temperature.
Comments16 pages, 6 figures
