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arXiv · 1102.1057

Common Fermi Surface Topology and Nodeless Superconducting Gap in K0.68Fe1.79Se2 and (Tl0.45K0.34)Fe1.84Se2 Superconductors Revealed from Angle-Resolved Photoemission Spectroscopy

Lin Zhao·Daixiang Mou·Shanyu Liu·Xiaowen Jia·Junfeng He·Yingying Peng·Li Yu·Xu Liu·Guodong Liu·Shaolong He·Xiaoli Dong·Jun Zhang·J. B. He·D. M. Wang·G. F. Chen·J. G. Guo·X. L. Chen·Xiaoyang Wang·Qinjun Peng·Zhimin Wang·Shenjin Zhang·Feng Yang·Zuyan Xu·Chuangtian Chen·X. J. Zhou
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Abstract

We carried out high resolution angle-resolved photoemission measurements on the electronic structure and superconducting gap of K_0.68Fe_1.79Se_2 (T_c=32 K) and (Tl_0.45K_0.34)Fe_1.84Se_2 (T_c=28 K) superconductors. In addition to the electron-like Fermi surface near M(π,π), two electron-like Fermi pockets are revealed around the zone center Γ(0,0) in K0.68Fe1.79Se_2. This observation makes the Fermi surface topology of K_0.68Fe_1.79Se_2 consistent with that of (Tl,Rb)_xFe_{2-y}Se_2 and (Tl,K)_xFe_{2-y}Se_2 compounds. A nearly isotropic superconducting gap (Δ) is observed along the electron-like Fermi pocket near the M point in K_0.68Fe_1.79Se_2 (Δ\sim 9 meV) and (Tl_0.45K_0.34)Fe_1.84Se_2 (Δ\sim 8 meV). The establishment of a universal picture on the Fermi surface topology and superconducting gap in the A_xFe_2-ySe_2 (A=K, Tl, Cs, Rb and etc.) superconductors will provide important information in understanding the superconductivity mechanism of the iron-based superconductors.

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Lin Zhao, Daixiang Mou, Shanyu Liu, Xiaowen Jia, Junfeng He, Yingying Peng, Li Yu, Xu Liu, Guodong Liu, Shaolong He, Xiaoli Dong, Jun Zhang, J. B. He, D. M. Wang, G. F. Chen, J. G. Guo, X. L. Chen, Xiaoyang Wang, Qinjun Peng, Zhimin Wang, Shenjin Zhang, Feng Yang, Zuyan Xu, Chuangtian Chen, X. J. Zhou. 2011-02-05. Common Fermi Surface Topology and Nodeless Superconducting Gap in K0.68Fe1.79Se2 and (Tl0.45K0.34)Fe1.84Se2 Superconductors Revealed from Angle-Resolved Photoemission Spectroscopy. https://doi.org/10.1103/physrevb.83.140508

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