Common Fermi-surface topology and nodeless superconducting gap of K0.68Fe1.79Se2 and (Tl0.45K0.34)Fe1.84Se2 superconductors revealed via angle-resolved photoemission

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

doi:10.1103/PhysRevB.83.140508

Common Fermi-surface topology and nodeless superconducting gap of K0.68Fe1.79Se2 and (Tl0.45K0.34)Fe1.84Se2 superconductors revealed via angle-resolved photoemission

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

DOI 10.1103/PhysRevB.83.140508 · Physical Review B

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Abstract

We carried out high-resolution angle-resolved photoemission measurements on the electronic structure and superconducting gap of K0.68Fe1.79Se2 (Tc=32 K) and (Tl0.45K0.34)Fe1.84Se2 (Tc=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 K0.68Fe1.79Se2. This observation makes the Fermi surface topology of K0.68Fe1.79Se2 consistent with that of (Tl, Rb)xFe2−ySe2 and (Tl, K)xFe2−ySe2 compounds. A nearly isotropic superconducting gap Δ is observed along the electron-like Fermi pocket near the M point in K0.68Fe1.79Se2 (Δ~9 meV) and (Tl0.45K0.34)Fe1.84Se2 (Δ~8 meV). The establishment of a universal picture on the Fermi surface topology and superconducting gap in the AxFe2−ySe2 (A=K, Tl, Cs, Rb, etc.) superconductors will provide important information for understanding the superconductivity mechanism of iron-based superconductors.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
K0.68Fe1.79Se2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	32	Pressure not reported	unknown
K0.68Fe1.79Se2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	32	Pressure not reported	unknown
K0.68Fe1.79Se2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	32	Pressure not reported	unknown
(Tl0.45K0.34)Fe1.84Se2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	28	Pressure not reported	unknown
(Tl0.45K0.34)Fe1.84Se2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	28	Pressure not reported	unknown
(Tl0.45K0.34)Fe1.84Se2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	28	Pressure not reported	unknown