Revealing the electron-spin fluctuation coupling by photoemission in CaKFe4As4

Fuente: arXiv
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Autori principali: Li, Peng, Wang, Yuzhe, Liu, Yabin, Yao, Jianghao, Zhao, Zhisheng, Liu, Zhengtai, Shen, Dawei, Luo, Huiqian, Cao, Guanghan, Jiang, Juan, Feng, Donglai
Natura: Preprint
Pubblicazione: 2025
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author Li, Peng
Wang, Yuzhe
Liu, Yabin
Yao, Jianghao
Zhao, Zhisheng
Liu, Zhengtai
Shen, Dawei
Luo, Huiqian
Cao, Guanghan
Jiang, Juan
Feng, Donglai
author_facet Li, Peng
Wang, Yuzhe
Liu, Yabin
Yao, Jianghao
Zhao, Zhisheng
Liu, Zhengtai
Shen, Dawei
Luo, Huiqian
Cao, Guanghan
Jiang, Juan
Feng, Donglai
contents 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 exciton 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 understanding of the electron-spin exciton interactions in unconventional superconductors.
format Preprint
id arxiv_https___arxiv_org_abs_2503_03473
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Revealing the electron-spin fluctuation coupling by photoemission in CaKFe4As4
Li, Peng
Wang, Yuzhe
Liu, Yabin
Yao, Jianghao
Zhao, Zhisheng
Liu, Zhengtai
Shen, Dawei
Luo, Huiqian
Cao, Guanghan
Jiang, Juan
Feng, Donglai
Superconductivity
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 exciton 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 understanding of the electron-spin exciton interactions in unconventional superconductors.
title Revealing the electron-spin fluctuation coupling by photoemission in CaKFe4As4
topic Superconductivity
url https://arxiv.org/abs/2503.03473