Decoupled interband pairing in a bilayer iron-based superconductor evidenced by ultrahigh-resolution ARPES
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arXiv
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| Main Authors: | , , , , , , , , , , , , , |
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| Format: | Preprint |
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2026
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| _version_ | 1866915723124670464 |
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| author | Wang, Shichong Yang, Yuanyuan Li, Yang Hong, Wenshan Li, Huaxun Duan, Shaofeng Gu, Lingxiao Liu, Haoran Huang, Jiongyu Liu, Jianzhe Qian, Dong Cao, Guanghan Luo, Huiqian Zhang, Wentao |
| author_facet | Wang, Shichong Yang, Yuanyuan Li, Yang Hong, Wenshan Li, Huaxun Duan, Shaofeng Gu, Lingxiao Liu, Haoran Huang, Jiongyu Liu, Jianzhe Qian, Dong Cao, Guanghan Luo, Huiqian Zhang, Wentao |
| contents | We present direct experimental evidence of a weakly coupled multiband superconducting state in the bilayer iron-based superconductor ACa$_2$Fe$_4$As$_4$F$_2$ (A = K, Cs) via ultrahigh-resolution angle-resolved photoemission spectroscopy (ARPES). Remarkably, the K-containing compound exhibits two distinct transition temperatures, corresponding to two separate sets of bilayer-split bands, as evidenced by temperature-dependent superconducting gap and spectral weight near the Fermi energy, while its Cs counterpart displays conventional single transition behavior. These experimental observations are well described by the weakly coupled two-band model of Eilenberger theory, which identifies suppressed interband pairing interactions between the bilayer-split bands as the key mechanism. By exploring quantum phenomena in the weak-coupling limit within a multiband system, our findings pave the way for engineering exotic superconductivity via band-selective pairing control. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2601_07380 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Decoupled interband pairing in a bilayer iron-based superconductor evidenced by ultrahigh-resolution ARPES Wang, Shichong Yang, Yuanyuan Li, Yang Hong, Wenshan Li, Huaxun Duan, Shaofeng Gu, Lingxiao Liu, Haoran Huang, Jiongyu Liu, Jianzhe Qian, Dong Cao, Guanghan Luo, Huiqian Zhang, Wentao Superconductivity Strongly Correlated Electrons We present direct experimental evidence of a weakly coupled multiband superconducting state in the bilayer iron-based superconductor ACa$_2$Fe$_4$As$_4$F$_2$ (A = K, Cs) via ultrahigh-resolution angle-resolved photoemission spectroscopy (ARPES). Remarkably, the K-containing compound exhibits two distinct transition temperatures, corresponding to two separate sets of bilayer-split bands, as evidenced by temperature-dependent superconducting gap and spectral weight near the Fermi energy, while its Cs counterpart displays conventional single transition behavior. These experimental observations are well described by the weakly coupled two-band model of Eilenberger theory, which identifies suppressed interband pairing interactions between the bilayer-split bands as the key mechanism. By exploring quantum phenomena in the weak-coupling limit within a multiband system, our findings pave the way for engineering exotic superconductivity via band-selective pairing control. |
| title | Decoupled interband pairing in a bilayer iron-based superconductor evidenced by ultrahigh-resolution ARPES |
| topic | Superconductivity Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2601.07380 |