A phenomenological heterophase model of the conductivity anomalies in high-temperature superconductors

Korzhenevskii, Alexander L.; Luzhkov, A. A.

doi:10.1016/0921-4534(92)90589-5

Cited by 3 publications

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“…The latter is usually described by the effective-medium approximation ͑EMA͒, 10 which proves to be very useful for the description of SN mixtures. [11][12][13][14][15] However, EMA by itself is incapable of analyzing the whole resistive transition (T), especially its low-temperature part, where T approaches T 0 . We combine the EMA, generalized for anisotropic mixtures, 14,16,17 with the theory of percolation of transport currents in SN mixtures.…”

Section: Introductionmentioning

confidence: 99%

Resistive transition anisotropy in superconducting granular ceramics: Interplay of effective medium approximation and percolation

et al. 2003

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The resistive transition (T,H) in granular high-T c superconductors is described by a combination of the effective-medium approximation for anisotropic mixtures with the percolation theory. We found a single parameter accounting for both the structural anisotropy as well as for the intrinsic resistivity anisotropy of a single grain. We obtained a direct ͑no fitting parameters͒ estimate of the superconducting volume fraction f as a function of temperature, as well as of the percolation threshold f p and of the zero-resisitivity threshold f 0 . The model describes successfully the experimental (T,H) dependence at different relative directions of the c axis, the current j and the magnetic field H in Bi 2 Sr 2 CaCu 2 O 8Ϫx ceramics. We provided estimates for the value of the Josephson critical current between grains. The latter proves to be strongly suppressed even by weak magnetic fields HϽ750 Oe. This results in the appearance of the field-induced excess resistivity ⌬ that obeys the dependence 1/⌬Ӎ1ϩH /H, where H is the characteristic field trapped by a single Josephson contact.

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