Relationship between the lattice parameter and superconductivity in the 2-1-4 series n-type cuprates

Cong Wang; Cheng Dong; Guangcan Che; Zhiyu Qiao; Hong Chen; Zhongxian Zhao

doi:10.1103/PhysRevB.55.3935

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Relationship between the lattice parameter and superconductivity in the 2-1-4 series n-type cuprates

Cong Wang, Cheng Dong, Guangcan Che, Zhiyu Qiao, Hong Chen, Zhongxian Zhao

DOI 10.1103/PhysRevB.55.3935 · Physical Review B

T1

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Abstract

The superconductivity of R2−x−yLayCexCuO4−δ (R=Nd, Gd, y=0, 0.2, 0.5,..., 1.4. x=0.10,..., 0.15,..., 0.25) series are studied. The solubility limit of La3+ in Nd1.85−yLayCe0.15CuO4−δ is determined to be ylim=1.3, while the Ce-solubility limit increases to Xlim=0.25 in Nd0.7−xLa1.3CexCuO4−δ with the maximum lattice parameter a=3.995 Å. The Tcon and the bulk superconducting fraction are found to decrease with increasing La content. However, the reduction of superconductivity induced by increasing lattice constant a can be compensated by a proper decrease of Ce content irrespective of the lattice parameter a up to 3.982 Å. These results indicate that the lattice parameters are not directly related to the superconductivity. Actually, both the change of the a parameter and the Ce content x induce a variation in oxygen vacancies δ and result in the change of the charge-carrier density. Taking these facts into account, we give a simplified formula to calculate the charge-carrier density n0 as n0=x+2δ=x+2(Aa+Bx+C0). In order to keep an optimum charge-carrier density for superconductivity, the variations in oxygen vacancies induced by the change of lattice parameter a must be compensated by an appropriate decrease of Ce dopant. This implies that the a parameter, doping concentration, oxygen vacancy, and the charge-carrier density can be taken into unified consideration, in which the charge-carrier density is considered to be a determining factor for superconductivity.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
Nd1.85Ce0.15CuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	26	Pressure not reported	onset
Nd1.85Ce0.15CuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	24	Pressure not reported	onset
Nd1.65La0.2Ce0.15CuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	26	Pressure not reported	onset
Nd1.65La0.2Ce0.15CuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	23	Pressure not reported	onset
Nd1.35La0.5Ce0.15CuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	26	Pressure not reported	onset
Nd1.35La0.5Ce0.15CuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	18	Pressure not reported	onset
Nd1.15La0.7Ce0.15CuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	26	Pressure not reported	onset
Nd1.15La0.7Ce0.15CuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	18	Pressure not reported	onset
Nd0.9La0.95Ce0.15CuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	26	Pressure not reported	onset
Nd0.9La0.95Ce0.15CuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	15	Pressure not reported	onset
Nd0.85La1.0Ce0.15CuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	26	Pressure not reported	onset
Nd0.85La1.0Ce0.15CuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	10	Pressure not reported	onset
Nd0.8La1.1Ce0.10CuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	27	Pressure not reported	onset
Nd0.8La1.1Ce0.10CuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	23	Pressure not reported	onset
Nd0.78La1.1Ce0.12CuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	26	Pressure not reported	onset
Nd0.78La1.1Ce0.12CuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	17	Pressure not reported	onset
Nd0.75La1.1Ce0.15CuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	26	Pressure not reported	onset
Nd0.65La1.2Ce0.15CuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	26	Pressure not reported	onset
Nd0.55La1.3Ce0.15CuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	26	Pressure not reported	onset