Correlation between hole density and oxygen excess in the Bi2Sr2CaCu2O8+δ superconductor

P. Ghigna; G. Spinolo; G. Flor; N. Morgante

doi:10.1103/PhysRevB.57.13426

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Correlation between hole density and oxygen excess in the Bi2Sr2CaCu2O8+δ superconductor

P. Ghigna, G. Spinolo, G. Flor, N. Morgante

DOI 10.1103/PhysRevB.57.13426 · Physical Review B

T1

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Abstract

Charge-carrier density in Bi-2212 oxide superconductor samples with well-defined cation molecularity has been measured by means of Cu−LIII x-ray absorption spectroscopy, as a function of the oxygen content, which was fixed to known values by annealing at predetermined T and P(O2), and subsequent quenching. The main results of this work can be summarized as follows: (i) at low oxygen content the hole density is greater than that one determined by the oxygen excess only; (ii) at intermediary oxygen content values the hole density is almost entirely determined by the oxygen excess only; each extra oxygen atom contributes two holes to the overall charge-carrier density; (iii) for the highest values of the oxygen content, each extra oxygen atom contributes only one hole to the overall charge-carrier density. From these results a band model is drawn in which the extra oxygen levels lie in energy near the Fermi level.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
Bi2Sr2CaCu2O8+δ Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
Bi2.15Sr1.48Ca1.37Cu2O8.075 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown