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Scaling of Complex Conductivity for A Percolating Metal-Insulator Composite with Inter granular Tunneling Above and Below the Superconducting Transition

Published online by Cambridge University Press:  10 February 2011

D. S. Mclachlan ,
A. B. Pakhomov ,
I. I. Oblachova ,
F. Brouers  and
A. Sarychev
D. S. Mclachlan
Affiliation:
Department of Physics, University of the Witwatersrand,Johannesburg,South Africa.
A. B. Pakhomov
Affiliation:
Department of Physics, University of the Witwatersrand,Johannesburg,South Africa.
I. I. Oblachova
Affiliation:
Ioffe Physical Technical Institute, Saint-Petersbourg 194021, Russia.
F. Brouers
Affiliation:
Materials Sciences,B5 Liège Univertsity, Liège 4000, Belgium.
A. Sarychev
Affiliation:
Center for Problems in Electrodynamics Russian Academy of Sciences, Moscow
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Abstract

The complex conductivity was measured on 3d granular NbC-KCI composite samples at varying metal volume fraction p, frequency ω and temperature above and below the superconductivity critical Tc. The observed frequency dispersion is anomalous in that it is not in accord with the scaling theory of percolation transition. The results are compared with a recently developed scaling theory, which takes both intercluster tunneling and intercluster capacitance into account. The experimental estimates for the new critical exponents are in reasonable agreement with the theory. The very low value of the crossover frequency can also be understood. We also present the data showing the dispersion of the complex conductivity well below the superconducting transition Tc of NbC.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 411: Symposium T – Electricaly-Based Microstructural Characterization , 1995 , 333
Copyright
Copyright © Materials Research Society 1996

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References

REFERENCES

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