Chin. Phys. Lett.  2008, Vol. 25 Issue (12): 4402-4405    DOI:
Original Articles |
Multiple Nodeless Superconducting Gaps in (Ba0.6K0.4)Fe2As2 Superconductor from Angle-Resolved Photoemission Spectroscopy
ZHAO Lin1, LIU Hai-Yun1, ZHANG Wen-Tao1, MENG Jian-Qiao1, JIA Xiao-Wen1, LIU Guo-Dong1, DONG Xiao-Li1, CHEN Gen-Fu2, LUO Jian-Lin2, WANG Nan-Lin2, LU Wei1, WANG Gui-Ling3, ZHOU Yong3, ZHU Yong4, WANG Xiao-Yang4, XU Zu-Yan3, CHEN Chuang-Tian4, ZHOU Xing-Jiang1
1National Laboratory for Superconductivity, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 1001902Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 1001903Key Laboratory for Optics, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 1001904Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190
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High resolution angle-resolved photoemission measurements have been carried out to study the superconducting gap in the (Ba0.6K0.4)Fe2As2 superconductor with Tc=35 K. Two hole-like Fermi surface sheets around the Γ point exhibit different superconducting gaps. The inner Fermi surface sheet shows larger (10~12 meV) and slightly momentum-dependent gap while the outer one has smaller (7~8meV) and nearly isotropic gap. The lack of gap node in both Fermi surface sheets favours s-wave superconducting gap symmetry. Superconducting gap opening is also observed at the M(π,π) point. The two Fermi surface spots near the M point are gapped below Tc but the gap persists above Tc. The rich and detailed superconducting gap information will provide key insights and constraints in understanding pairing mechanism in the iron-based superconductors.

Keywords: 74.70.-b      74.25.Jb      79.60.-i      71.20.-b     
Received: 25 September 2008      Published: 27 November 2008
PACS:  74.70.-b (Superconducting materials other than cuprates)  
  74.25.Jb (Electronic structure (photoemission, etc.))  
  79.60.-i (Photoemission and photoelectron spectra)  
  71.20.-b (Electron density of states and band structure of crystalline solids)  
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ZHAO Lin, LIU Hai-Yun, ZHANG Wen-Tao et al  2008 Chin. Phys. Lett. 25 4402-4405
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LIU Hai-Yun
MENG Jian-Qiao
JIA Xiao-Wen
LIU Guo-Dong
DONG Xiao-Li
LUO Jian-Lin
WANG Nan-Lin
LU Wei
WANG Gui-Ling
ZHU Yong
WANG Xiao-Yang
XU Zu-Yan
CHEN Chuang-Tian
ZHOU Xing-Jiang
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