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Observation of a Van Hove singularity and implication for strong-coupling induced Cooper pairing in

DOI: 10.1103/PhysRevB.92.144513 DOI Help

Authors: Delong Fang (Nanjing University) , Xun Shi (Institute of Physics, Chinese Academy of Sciences) , Zengyi Du (Nanjing University) , Pierre Richard (Institute of Physics, Chinese Academy of Sciences) , Huan Yang (Nanjing University) , X. X. Wu (Chinese Academy of Sciences) , Peng Zhang (Chinese Academy of Sciences) , Tian Qian (Chinese Academy of Sciences) , Xiaxin Ding (Nanjing University) , Zhenyu Wang (Chinese Academy of Sciences) , T. K. Kim (Diamond Light Source) , Moritz Hoesch (Diamond Light Source) , Aifeng Wang (University of Science and Technology of China) , Xianhui Chen (University of Science and Technology of China) , Jiangping Hu (Chinese Academy of Sciences) , Hong Ding (Chinese Academy of Sciences) , Hai-Hu Wen (Nanjing University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Review B , VOL 92 (14)

State: Published (Approved)
Published: October 2015

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.

Subject Areas: Physics, Materials

Instruments: I05-ARPES

Added On: 01/11/2015 18:30

Discipline Tags:

Superconductors Quantum Materials Hard condensed matter - electronic properties Physics Materials Science

Technical Tags:

Spectroscopy Angle Resolved Photoemission Spectroscopy (ARPES)