The compounds CaREBaCu3O7-y (RE=La and Sm) are tetragonal at room temperature with Tc between 60 and 70 K. The single-phase compounds were prepared by solid-state reaction. The resistivity was measured by a four-probe technique in a continuous flow cryostat with the temperature being controlled to an accuracy of 10 mK. The resistivity vs temperature showed a break in slope around 180 K in CaLaBaCu3O7-y and around 220 K in CaSmBaCu3O7-y . The results were analysed for fluctuation conductivity from 180 K downwards. A plot of d ρ/d T vs T showed a sharp peak at Tm =69·69 K for La compound and 66·00 K for the Sm compound. Detailed analysis of the resistivity in the region Ton to 180 K was carried out using the procedure due to Veira and Vidal. The results are discussed in this paper. © 1991 Indian Academy of Sciences.

Sankaranarayanan V

Department Of Physics

H. Krishnan

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IIT Madras

Fluctuation-induced excess conductivity in the compounds CaREBaCu3O7−y (RE=La and Sm)

Bulletin of Materials Science

Fluctuations in phase across the weak links in a granular superconductor contribute to the excess conductivity below Tm, the temperature at which the plot of temperature derivative of electrical resistivity against temperature shows a maximum. In a narrow range of temperature above T∞ (the temperature at which the resistivity at which the resistivity becomes zero), the excess conductivity, Δσ = [σ(T) - σ(Tm)], is expected to vary as (T-T∞)-γ. In this work, resistivity measurements on CaREBaCu3O7-y (RE=La, Sm), Ag coated YBa2Cu3O7-y, Tl2CaBa2Cu2O8 and YBa2Cu3-xZnxCu3O7-y (x=0.05, 0.075, 0.1 and 0.15) in the paracoherence region are reported. Analysis of the data indicates the excess conductivity in this region is better described by the critical exponent y = 1.33. From an analogy between the tunneling Hamiltonian in the granular material and the Hamiltonian for an XY ferromagnet one expects the critical exponent, γ, to be the same as the critical exponent for susceptibility in the ferromangetic case. © 1992.

Physica C: Superconductivity and its applications

Excess conductivity studies in the paracoherence region in high- temperature superconductors

Physica Scripta

A Tribute

Journal of Applied Physics

Method for Measuring Electrical Resistivity of Anisotropic Materials

Physical Review B

Fluctuation conductivity of Tl-Ba-Ca-Cu-O thin films

Preparation, characterization, and superconducting properties of tetragonalLaBaCaCu3O7+δ

Anomalous in-plane paraconductivity in single-crystal YBa2Cu3O7

Fluctuation-induced excess conductivity in the compounds CaREBaCu3O7-y (RE=La and Sm)

Journal	Data powered by TypesetBulletin of Materials Science
Publisher	Data powered by TypesetSpringer India
ISSN	02504707
Open Access	Yes