Observation of a Van Hove singularity and implication for strong-coupling induced Cooper pairing in KFe2As2
Delong Fang, Xun Shi, Zengyi Du, Pierre Richard, Huan Yang, X. X. Wu, Peng Zhang, Tian Qian, Xiaxin Ding, Zhenyu Wang, T. K. Kim, M. Hoesch, Aifeng Wang, Xianhui Chen, Jiangping Hu, Hong Ding, Hai-Hu Wen
DOI 10.1103/PhysRevB.92.144513 · Physical Review B
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Abstract
Scanning tunneling spectroscopy and angle-resolved photoemission spectroscopy have been investigated on single-crystal samples of KFe2As2. A Van Hove singularity (VHS) has been directly observed just a few meV below the Fermi level (EF) of superconducting KFe2As2, which locates in the middle of the principal axes of the first Brillouin zone. The majority of the density of states at EF, mainly contributed by the proximity effect of the saddle point to EF, is nongapped in the superconducting state. Our observation of the ungapped feature of the density of states due to the VHS points, while providing consistent explanations to many exotic behaviors previously observed in this material, suggests Cooper pairing induced by a strong-coupling mechanism.
Source-reported materials — not catalogue approval
| Formula | Reported Tc (K) | Pressure (GPa) | Type |
|---|---|---|---|
| KFe2As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 3.6 | Pressure not reported | unknown |
| KFe2As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 3.6 | Pressure not reported | unknown |
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