Temperature dependence of the positron annihilation parameters in Bi2−xPbxCa2Sr2Cu3Oy and Bi2CaSr2Cu2Oy superconductors

P. K. Pujari; T. Datta; Udayan De; B. Ghosh

doi:10.1103/PhysRevB.50.3438

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Temperature dependence of the positron annihilation parameters in Bi2−xPbxCa2Sr2Cu3Oy and Bi2CaSr2Cu2Oy superconductors

P. K. Pujari, T. Datta, Udayan De, B. Ghosh

DOI 10.1103/PhysRevB.50.3438 · Physical Review B

T1

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Abstract

We report the results of temperature dependence of S-parameter and lifetime (τ) measurements on the normal and superconducting states of Bi2CaSr2Cu2Oy (Bi-2:1:2:2) and Bi2−xPbxCa2Sr2Cu3Oy (Bi-2:2:2:3) superconductors. A decrease of the S parameter as well as τ below Tc is seen for both compounds. These observations are interpreted qualitatively considering a reported positron-density-distribution calculation and invoking the local charge-transfer process from CuO2 to Bi-O planes at the onset of the superconducting transition. The possible influence of sample preparation conditions and structural changes on the temperature dependencies of the positron annihilation parameters across Tc is also discussed.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
Bi2-xPbxCa2Sr2Cu3Oy Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	106	Pressure unresolved	zero_resistance
Bi2CaSr2Cu2Oy Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	53	Pressure unresolved	zero_resistance