Excess Conductivity of Anisotropic Inhomogeneous Superconductors Above the Critical Temperature
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The theoretical model of conductivity of a layered anisotropic normal metal containing small superconducting ellipsoidal granules with an arbitrary ratio of semiaxes is developed. Calculation data obtained under two simple approximations (self-consistent and Maxwell) are compared. The results may be applied in the analysis of the observed temperature dependence of the conductivity anisotropy in various anisotropic superconductors with the superconducting phase emerging in the form of isolated superconducting granules. The temperature dependence of the electric resistance along and across the conducting layers above and near the superconducting transition temperature is studied experimentally for bridge structures of a varying thickness. It is demonstrated that this resistance and even the effective superconducting transition temperature depend strongly on the bridge thickness (i.e., the number of layers through which the electric current flows). Note that significant differences were observed only for the resistance across the layers.
Keywords:conductivity superconductors anisotropy inhomogeneity
T.I. Mogilyuk acknowledges support from the Russian Foundation for Basic Research (grant nos. 18-02-01022, 18-02-00280, 18-32-00205, and 19-02-01000). The work of P.D. Grigoriev was supported by state task no. 0033-2019-0001 “Development of Theory of Condensed Matter.” This study was supported in part by the BASIS Foundation for the Advancement of Theoretical Physics and Mathematics. A.A. Sinchenko acknowledges support from the Russian Foundation for Basic Research (grant no. 17-29-10007). The work of A.V. Frolov and A.P. Orlov was supported by the state task for the Kotel’nikov Institute of Radio Engineering and Electronics.
CONFLICT OF INTEREST
The authors declare that they have no conflicts of interest.
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