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Excess conductivity studies in the paracoherence region in high- temperature superconductors
, H. Krishnan
Published in
1992
Volume: 194
   
Issue: 1-2
Pages: 163 - 170
Abstract
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.
About the journal
JournalPhysica C: Superconductivity and its applications
ISSN09214534
Open AccessNo
Concepts (10)
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    HIGH TEMPERATURE SUPERCONDUCTORS - GRAIN BOUNDARIES
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    HIGH TEMPERATURE SUPERCONDUCTORS - PHASE TRANSITIONS
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    HIGH TEMPERATURE SUPERCONDUCTORS - THERMAL EFFECTS
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    Critical exponent
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    Excess conductivity
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    GRANULAR SUPERCONDUCTOR
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    PARACOHERENCE REGION
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    PHASE FLUCTUATIONS
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    TUNNELING HAMILTONIAN
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    High temperature superconductors