Superconductivity at 38 K in the Iron Arsenide (Ba1−xKx)Fe2As2

Marianne Rotter; Marcus Tegel; Dirk Johrendt

doi:10.1103/PhysRevLett.101.107006

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Superconductivity at 38 K in the Iron Arsenide (Ba1−xKx)Fe2As2

Marianne Rotter, Marcus Tegel, Dirk Johrendt

DOI 10.1103/PhysRevLett.101.107006 · Physical Review Letters

T1

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Abstract

The ternary iron arsenide BaFe2As2 becomes superconducting by hole doping, which was achieved by partial substitution of the barium site with potassium. We have discovered bulk superconductivity at Tc=38 K in (Ba1−xKx)Fe2As2 with x≈0.4. The parent compound BaFe2As2 crystallizes in the tetragonal ThCr2Si2-type structure, which consists of (FeAs)δ− iron arsenide layers separated by Ba2+ ions. BaFe2As2 is a poor metal and exhibits a spin density wave anomaly at 140 K. By substituting Ba2+ for K+ ions we have introduced holes in the (FeAs)− layers, which suppress the anomaly and induce superconductivity. The Tc of 38 K in (Ba0.6K0.4)Fe2As2 is the highest in hole doped iron arsenide superconductors so far. Therefore, we were able to expand this class of superconductors by oxygen-free compounds with the ThCr2Si2-type structure.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
(Ba0.6K0.4)Fe2As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	38.1	Pressure not reported	midpoint
(Ba0.6K0.4)Fe2As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	37.2	Pressure not reported	zero_resistance
(Ba0.6K0.4)Fe2As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	38.3	Pressure not reported	onset
LaFeAs(O1-xFx) Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	26	Pressure not reported	unknown
(La1-xSrx)FeAsO Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	25	Pressure not reported	unknown
LaFePO Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	5	Pressure not reported	unknown
LaNiPO Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	5	Pressure not reported	unknown
LaIr2Ge2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	5	Pressure not reported	unknown
LaRu2P2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	5	Pressure not reported	unknown
YIr2-xSi2+x Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	5	Pressure not reported	unknown
BaNi2P2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	5	Pressure not reported	unknown
YPd2B2C Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	26	Pressure not reported	unknown