Revealing the Electron-Spin Fluctuation Coupling by Photoemission in CaKFe4As4

IF 11.6 1区物理与天体物理 Q1 PHYSICS, MULTIDISCIPLINARY

Physical Review X Pub Date : 2025-04-02 DOI:10.1103/physrevx.15.021001

Peng Li, Yuzhe Wang, Yabin Liu, Jianghao Yao, Zhisheng Zhao, Zhengtai Liu, Dawei Shen, Huiqian Luo, Guanghan Cao, Juan Jiang, Donglai Feng

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引用次数: 0

Abstract

Electron-boson coupling in unconventional superconductors is one of the key parameters in understanding the superconducting pairing symmetry. Here, we report definitive photoemission evidence of electron-spin fluctuation coupling in the iron-based superconductor CaKFe4As4, obtained via high-resolution ARPES. Our study identifies a distinct kink structure on the α band, observable only in the superconducting phase and closely linked with the superconductivity, indicative of strong electron-boson interactions. Notably, this kink structure corresponds to two distinct bosonic modes at 11 meV and 13 meV, aligning with spin resonance modes previously observed in inelastic neutron-scattering experiments. This alignment underscores the significant role of antiferromagnetic fluctuations in the pairing mechanism of this superconductor. Furthermore, the unique momentum-dependent and orbital-selective properties of the coupling revealed by ARPES provide profound insights into the pairing symmetry, suggesting predominantly s±-wave pairing facilitated by spin fluctuations. Our findings not only highlight the pivotal role of spin resonance in the superconductivity of CaKFe4As4 but also enhance our understanding of the electron-spin fluctuation interactions in unconventional superconductors.

Published by the American Physical Society

2025

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光电发射揭示CaKFe4As4中电子-自旋涨落耦合

非常规超导体中的电子-玻色子耦合是理解超导对对称性的关键参数之一。在这里，我们报告了铁基超导体CaKFe4As4中电子-自旋涨落耦合的明确光发射证据，通过高分辨率ARPES获得。我们的研究确定了α带上独特的扭结结构，仅在超导相中可见，并与超导性密切相关，表明了强电子-玻色子相互作用。值得注意的是，这种扭结结构对应于11 meV和13 meV的两种不同的玻色子模式，与之前在非弹性中子散射实验中观察到的自旋共振模式一致。这种排列强调了反铁磁波动在这种超导体的配对机制中的重要作用。此外，ARPES揭示的独特的动量依赖和轨道选择特性为配对对称性提供了深刻的见解，表明自旋涨落促进了s±波配对。我们的发现不仅突出了自旋共振在CaKFe4As4超导性中的关键作用，而且增强了我们对非常规超导体中电子-自旋涨落相互作用的理解。2025年由美国物理学会出版

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来源期刊

Physical Review X PHYSICS, MULTIDISCIPLINARY-

CiteScore

24.60

自引率

1.60%

发文量

197

审稿时长

3 months

期刊介绍： Physical Review X (PRX) stands as an exclusively online, fully open-access journal, emphasizing innovation, quality, and enduring impact in the scientific content it disseminates. Devoted to showcasing a curated selection of papers from pure, applied, and interdisciplinary physics, PRX aims to feature work with the potential to shape current and future research while leaving a lasting and profound impact in their respective fields. Encompassing the entire spectrum of physics subject areas, PRX places a special focus on groundbreaking interdisciplinary research with broad-reaching influence.