Revealing the Electron-Spin Fluctuation Coupling by Photoemission in CaKFe_{4}As_{4}
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 CaKFe_{4}As_{4}, obtained via high-re...
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| Main Authors: | , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
American Physical Society
2025-04-01
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| Series: | Physical Review X |
| Online Access: | http://doi.org/10.1103/PhysRevX.15.021001 |
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| Summary: | 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 CaKFe_{4}As_{4}, 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 CaKFe_{4}As_{4} but also enhance our understanding of the electron-spin fluctuation interactions in unconventional superconductors. |
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| ISSN: | 2160-3308 |