Origin of the semiconducting-to-superconducting transition of La2−xCa1+xCu2O6±δ under high-oxygen-pressure annealing

H. Shibata; A. Matsuda; K. Kinoshita; T. Watanabe; T. Yamada

doi:10.1103/PhysRevB.49.12315

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Origin of the semiconducting-to-superconducting transition of La2−xCa1+xCu2O6±δ under high-oxygen-pressure annealing

H. Shibata, A. Matsuda, K. Kinoshita, T. Watanabe, T. Yamada

DOI 10.1103/PhysRevB.49.12315 · Physical Review B

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Abstract

The Madelung energy of La2−xCa1+xCu2O6±δ system, whose properties change from semiconductor to superconductor under high-oxygen-pressure annealing, is calculated. We find the increase in ΔVA, the difference in Madelung site potential between the apex and the CuO2 planes’ oxygen, promotes the superconducting transition in this system. Slight intercalation of oxygen between two CuO2 planes is found to be of primary importance in determining ΔVA.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
La1.82Ca1.18Cu2O6.014 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	49	Pressure not reported	unknown
La1.82Ca1.18Cu2O5.99 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
La1.9Ca1.1Cu2O6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
La2CaCu2O6.037 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown