Defect and dopant properties of the oxyfluoride superconductor Sr2 CuO2 F2+δs

S. D'Arco; M. S. Islam

doi:10.1103/PhysRevB.55.3141

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Defect and dopant properties of the oxyfluoride superconductor Sr2 CuO2 F2+δs

S. D'Arco, M. S. Islam

DOI 10.1103/PhysRevB.55.3141 · Physical Review B

T1

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Abstract

Computer simulation techniques are used to investigate the defect and dopant properties of the oxyfluoride superconductor, Sr2 CuO2 F2+δ . The observed La2 CuO4 -type structure is correctly reproduced by our interatomic potential model. Defect calculations find that the most favorable fluorine interstitial position is near the ideal site and is associated with significant local relaxation, in accord with diffraction studies. A variety of redox reactions relevant to high-Tc behavior have been examined. Our results confirm that oxidation, involving fluorine incorporation at interstitial sites, is the most favorable process to introduce the holes necessary for superconductivity. We also consider the energetics of a range of dopant substitutions (alkali and alkaline-earth ions) at the Sr site.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
Sr2CuO2F2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	46	Pressure not reported	unknown
Ca2-xNaxCuO2Cl2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
(Sr,Ca)3Cu2O4Cl2-y Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	80	Pressure not reported	unknown