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- Title
Observation of a ubiquitous three-dimensional superconducting gap function in optimally doped Ba<sub>0.6</sub>K<sub>0.4</sub>Fe<sub>2</sub>As<sub>2</sub>.
- Authors
Xu, Y-M.; Huang, Y-B.; Cui, X-Y.; Razzoli, E.; Radovic, M.; Shi, M.; Chen, G-F.; Zheng, P.; Wang, N-L.; Zhang, C-L.; Dai, P-C.; Hu, J-P.; Wang, Z.; Ding, H.
- Abstract
The iron-pnictide superconductors have a layered structureformed by stacks of FeAs planes from which the superconductivity originates. Given the multiband and quasi three-dimensional (3D) electronic structure of these high-temperature superconductors, knowledge of the quasi-3D superconducting (SC) gap is essential for understanding the superconducting mechanism. By using the kz capability of angle-resolved photoemission, we completely determined the SC gap on all five Fermi surfaces (FSs) in three dimensions on Ba0.6K0.4Fe2As2 samples. We found a marked kz dispersion of the SC gap, which can derive only from interlayer pairing. Remarkably, the SC energy gaps can be described by a single 3D gap function with two energy scales characterizing the strengths of intralayer Δ1 and interlayer Δ2 pairing. The anisotropy ratio Δ1/Δ2, determined from the gap function, is close to the c-axis anisotropy ratio of the magnetic exchange coupling Jc/Jab in the parent compound. The ubiquitous gap function for all the 3D FSs reveals that pairing is short-ranged and strongly constrains the possible pairing force in the pnictides. A suitable candidate could arise from short-range antiferromagnetic fluctuations.
- Subjects
SUPERCONDUCTORS; SUPERCONDUCTIVITY; ELECTRONIC structure; ELECTRONIC systems; SUPERCONDUCTING magnets; FERROMAGNETIC material fluctuations; ANISOTROPY
- Publication
Nature Physics, 2011, Vol 7, Issue 3, p198
- ISSN
1745-2473
- Publication type
Article
- DOI
10.1038/nphys1879