Superconductivity and antiferromagnetism in La2−xCa1+xCu2O6±δ and La2−xSrxCaCu2O6±δ

K. Kinoshita; T. Yamada

doi:10.1103/PhysRevB.46.9116

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Superconductivity and antiferromagnetism in La2−xCa1+xCu2O6±δ and La2−xSrxCaCu2O6±δ

K. Kinoshita, T. Yamada

DOI 10.1103/PhysRevB.46.9116 · Physical Review B

T1

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Abstract

La2CaCu2O6 can be made superconducting by doping Ca or Sr in the form of La2−x(Sr,Ca)xCaCu2O6+δ and by synthesis under high O2 pressures of more than 4 atm. Superconducting properties of La2−xCa1+xCu2O6±δ (0.08≤x≤0.25) and La2−xSrxCaCu2O6±δ (0.07≤x≤0.23) as functions of composition (x) and oxygen partial pressure during synthesis (PO2 up to 400 atm) were investigated by measuring their electrical resistivity and magnetic susceptibility. In both compounds, the superconducting transition temperature (Tc) increased with increasing x and PO2, and showed almost the same maximum Tc (zero) of about 51 K at the solubility limit of Ca or Sr in La (x≊0.25) with PO2 at 400 atm, although at a lower PO2, Tc (zero) was higher in a Sr-doped compound than that of a Ca- doped compound. Nonsuperconducting or weakly superconducting La2−xCa1+xCu2O6±δ and La2−xSrxCaCu2O6±δ synthesized under oxygen partial pressures between 0.2 and 10 atm showed cusps in their magnetic susceptibility at around 25 K, which may result from three-dimensional (3D) antiferromagnetic ordering. The superconductivity of these compounds may appear as a result of the frustration of such 3D antiferromagnetic correlation as with other copper oxide superconductors.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
La1.82Ca1.18Cu2O6±δ Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	49	Pressure not reported	zero_resistance
La1.82Ca1.18Cu2O6±δ Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	60	Pressure not reported	onset
La2-xCa1+xCu2O6±δ Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	51	Pressure not reported	zero_resistance
La2-xSrxCaCu2O6±δ Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	51	Pressure not reported	zero_resistance
La1.6Sr0.4CaCu2O6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
La1.85(Ca0.86Sr0.14)1.15Cu2O6.03 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown