Common Fermi-surface topology and nodeless superconducting gap of K0.68Fe1.79Se2 and (Tl0.45K0.34)Fe1.84Se2 superconductors revealed via angle-resolved photoemission
/ Authors
Lin Zhao, D. Mou, Shanyu Liu, X. Jia, Junfeng He, Y. Peng, Li Yu, Xu Liu, Guodong Liu, Shaolong He
and 15 more authors
Xiaoli Dong, Jun Zhang, J. He, D. M. Wang, G. Chen, J. G. Guo, X. L. Chen, Xiaoyang Wang, Qin-jun Peng, Zhimin Wang, Shen-jin Zhang, Feng Yang, Zu-Yan Xu, Chuangtian Chen, X. Zhou
/ Abstract
We carried out high-resolution angle-resolved photoemission measurements on the electronic structure and superconducting gap of K0.68Fe1.79Se2 (T-c = 32 K) and (Tl0.45K0.34)Fe1.84Se2 (T-c = 28 K) superconductors. In addition to the electron-like Fermi surface near M(pi, pi), two electron-like Fermi pockets are revealed around the zone center Gamma (0,0) in K0.68Fe1.79Se2. This observation makes the Fermi surface topology of K0.68Fe1.79Se2 consistent with that of (Tl, Rb)(x)Fe2-ySe2 and (Tl, K)(x)Fe2-ySe2 compounds. A nearly isotropic superconducting gap Delta is observed along the electron-like Fermi pocket near the M point in K0.68Fe1.79Se2 (Delta similar to 9 meV) and (Tl0.45K0.34)Fe1.84Se2 (Delta similar to 8 meV). The establishment of a universal picture on the Fermi surface topology and superconducting gap in the A(x)Fe(2-y)Se(2) (A = K, Tl, Cs, Rb, etc.) superconductors will provide important information for understanding the superconductivity mechanism of iron-based superconductors.
Journal: Physical Review B