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KFe2Se2 is the Parent Compound of K-Doped Iron Selenide Superconductors

Wei Li, Hao Ding, Zhi Li, Peng Deng, Kai Chang, Ke He, Shuaihua Ji, Lili Wang, Xucun Ma, Jiang-Ping Hu, Xi Chen, Qi-Kun Xue

DOI 10.1103/PhysRevLett.109.057003 · Physical Review Letters

T1

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Abstract

We elucidate the existing controversies in the newly discovered K-doped iron selenide (KxFe2−ySe2−z) superconductors. The stoichiometric KFe2Se2 with 2×2 charge ordering was identified as the parent compound of KxFe2−ySe2−z superconductor using scanning tunneling microscopy and spectroscopy. The superconductivity is induced in KFe2Se2 by either Se vacancies or interacting with the antiferromagnetic K2Fe4Se5 compound. In total, four phases were found to exist in KxFe2−ySe2−z: parent compound KFe2Se2, superconducting KFe2Se2 with 2×5 charge ordering, superconducting KFe2Se2−z with Se vacancies, and insulating K2Fe4Se5 with 5×5 Fe vacancy order. The phase separation takes place at the mesoscopic scale under standard molecular beam epitaxy conditions.

Source-reported materials — not catalogue approval

FormulaReported Tc (K)Pressure (GPa)Type
KFe2Se2

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—Pressure not reportedunknown
KFe2Se2-z

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Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.

—Pressure not reportedunknown

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