具有在位交换相互作用的库珀对：高温超导的一种可能机制

中文摘要 AI 辅助

在为非常规超导提出的各种机制中，本文聚焦于导致铜酸盐和铁基氮化物中d波和s±波配对对称性的库仑相互作用。尽管有效相互作用\(U_{eff}=U - J\)主要是排斥的，但由洪德耦合参数\(J\)产生的吸引分量足以束缚分数电荷。在单带哈伯德模型中评估这种结合能可得出超导配对能隙\(\Delta_0\)并估计转变温度\(T_c\)。该模型专注于承载这些分数电荷的掺杂超导平面，得出了依赖于哈伯德\(U\)和洪德\(J\)参数的解析表达式以准确再现超导穹顶。此外，该模型通过考虑洪德耦合参数成功解决了在铜酸盐中观察到的特征性电子和空穴掺杂不对称问题。最后，虽然该理论准确描述了奇异金属行为，但目前仅对赝能隙相和欠掺杂同位素效应提供了定性解释。

英文摘要

Among the various mechanisms proposed for unconventional superconductivity, this paper focuses on the Coulomb interaction responsible for $d$-wave and $s_\pm$-wave pairing symmetries in cuprates and iron pnictides. Although the effective multi-orbital interaction $U_\text{eff}=U-J$ is predominantly repulsive, an attractive component driven by the Hund's coupling parameter $J$ is sufficient to bind fractional charges. This attractive multi-orbital contribution and a repulsive term of the single-band Hubbard model yield the superconducting pairing gap $Δ_0$ and an estimate of the transition temperature $T_c$. Given the complex electronic structure and vast compositional space of these materials, the model focuses exclusively on the doped superconducting plane hosting these fractional charges. Through this approach, an analytical expression mainly dependent on the Hubbard $U$ and Hund $J$ parameters that reproduces the empirical superconducting dome is derived. Furthermore, the model addresses the characteristic electron and hole doping asymmetry observed in cuprates by accounting for Hund's coupling parameters. Finally, while the model describes strange metal behavior, it currently provides only a qualitative explanation for the pseudogap phase and the underdoped isotope effect.

发表机构

• University of Yaoundé I（雅温得第一大学）

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