Chang M-H, Backes S, Lu D, Gauthier N, Hashimoto M, Chen G-Y, Wen H-H, Mo S-K, Valentí R, Pfau H
Department of Physics, The Pennsylvania State University, University Park, PA, USA.
RIKEN iTHEMS, Wako, Saitama 351-0198, Japan; Center for Emergent Matter Science, RIKEN, Wako, Saitama, Japan.
Nat Commun. 2024 Nov 17;15(1):9958. doi: 10.1038/s41467-024-54330-x.
The attractive interaction in conventional BCS superconductors is provided by a bosonic mode. However, the pairing glue of most unconventional superconductors is unknown. The effect of electron-boson coupling is therefore extensively studied in these materials. A key signature is dispersion kinks that can be observed in the spectral function as abrupt changes in velocity and lifetime of quasiparticles. Here, we show the existence of two kinks in the unconventional iron-based superconductor RbFeAs using angle-resolved photoemission spectroscopy (ARPES) and dynamical mean field theory (DMFT). In addition, we observe the formation of a Hubbard band multiplet due to the combination of Coulomb interaction and Hund's rule coupling in this multiorbital system. We demonstrate that the two dispersion kinks are a consequence of these strong many-body interactions. This interpretation is in line with a growing number of theoretical predictions for kinks in various general models of correlated materials. Our results provide a unifying link between iron-based superconductors and different classes of correlated, unconventional superconductors such as cuprates and heavy-fermion materials.
传统BCS超导体中的吸引相互作用由玻色子模式提供。然而，大多数非常规超导体的配对机制尚不清楚。因此，电子-玻色子耦合效应在这些材料中得到了广泛研究。一个关键特征是色散扭结，它可以在谱函数中作为准粒子速度和寿命的突然变化而被观察到。在这里，我们利用角分辨光电子能谱（ARPES）和动态平均场理论（DMFT），展示了非常规铁基超导体RbFeAs中存在两个扭结。此外，我们观察到在这个多轨道系统中，由于库仑相互作用和洪德规则耦合的结合，形成了一个哈伯德带多重态。我们证明这两个色散扭结是这些强多体相互作用的结果。这种解释与各种关联材料通用模型中关于扭结的越来越多的理论预测一致。我们的结果在铁基超导体与不同类型的关联非常规超导体（如铜酸盐和重费米子材料）之间提供了一个统一的联系。
