Decoupled interband pairing in a bilayer iron-based superconductor evidenced by ultrahigh-resolution angle-resolved photoemission spectroscopy
Year: 2025
Type: article
Abstract: 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.
DOI: 10.1103/vy32-xtt9
Authors: Shichong Wang, Yuanyuan Yang, Yang Li, Wenshan Hong, Huaxun Li, Shaofeng Duan, Lingxiao Gu, Haoran Liu, Jiongyu Huang, Jianzhe Liu, Dong Qian, Guanghan Cao, Huiqian Luo, Wentao Zhang
Language: English
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W4417248751