Self-similarity in the I-V characteristics of granular YBa2Cu3O7

Bungre, S; Cassidy, S.M.; Caplin, A.D.; Alford, N.McN.; Button, T.W.

doi:10.1088/0953-2048/4/1s/069

Cited by 15 publications

(7 citation statements)

References 9 publications

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“…A current-controlled percolation therefore is established in the paracoherent state which is characterized by the non-linear CVC of the samples. The non-linearity in CVC can be expressed in a breakdown form [40] as…”

Section: Current-voltage Characteristics and Paracoherent Regimementioning

confidence: 99%

Granularity controlled percolative current conduction in YBa₂Cu₃O₇/Ag composite thick films

Behera

Mishra

2001

Supercond. Sci. Technol.

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Temperature-dependent electrical resistivity in a set of YBa 2 Cu 3 O 7 /Ag thick films prepared by reaction diffusion technique is analysed to estimate the extent of granularity in them. Percolative nature of charge transfer in the films was examined by studying the excess conductivity in the superconducting order parameter fluctuation (SCOPF) region (T T c ), the approach to zero-resistance state in the tail region, the current-controlled tailing of the resistivity transition near T c 0 (T c 0 < T < T c 0 ) and the current-voltage characteristics in the paracoherent regime (T < T c 0 ) with their associated exponents. The percolative current model was thus utilized to quantify granularity in the films of such parameters like the weak link resistivity across grain boundaries, current path lengthening factor arising due to grain misalignment, and due to voids and cracks. Evolution of these parameters with Ag content in the films indicates reduced structural defects (voids and cracks) at higher Ag concentrations. The result points to a mechanism of grain growth in the composites, which accounts for the improved grain growth with narrower grain size distribution in these systems as compared to that in Ag-free YBCO sintered material. These microstructural modifications cause lowering of percolation threshold from the value expected in a granular system where the grain size approaches to one of the system dimensions (the film thickness) making the conduction through grain boundary essentially two-dimensional.

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Section: Current-voltage Characteristics and Paracoherent Regimementioning

confidence: 99%

Granularity controlled percolative current conduction in YBa₂Cu₃O₇/Ag composite thick films

Behera

Mishra

2001

Supercond. Sci. Technol.

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“…The response to an applied electric field of the three-dimensional Josephson network can be calculated, a power law V ∝ (I − I c ) a being obtained in a phase-coherent state above the critical current [80,122]. The experimental support was originally provided by measurements on specially prepared classical superconducting arrays [80] but soon afterwards also by a number of papers reporting results on HTS samples [82,96,[123][124][125][126]. The interpretation of results on polycrystalline HTSs includes usually other peculiarities of these systems, e.g.…”

Section: Initial Dissipation and Current-voltage Characteristicsmentioning

confidence: 99%

Current transfer and initial dissipation in high- superconductors

Prester

1998

Supercond. Sci. Technol.

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Various aspects of the problem of current transfer in high- superconductors (HTSs) are reviewed. The spatial inhomogeneities of various types are identified as a primary cause of non-uniformity of both normal currents and supercurrents in real samples of HTSs. The role these inhomogeneities play in transport features of the samples is discussed. The case of grain boundaries in polycrystalline samples is elaborated in detail. The local structural and transport properties of isolated grain boundaries are first reviewed and then integrated into the knowledge of global (macroscopic) charge transport. The paper emphasizes the common ingredients characterizing the transport in various forms and families of HTS samples in small magnetic fields. The phenomenon of percolation is identified as the most obvious one and is shown to dominate a large number of observations covered by this report. The experimental results focused on by this report elaborate primarily the problems of critical currents, initial dissipation and current-voltage characteristics, penetration depth, resistive and metal-insulator transition, resistance noise and magneto-optical studies of current paths. Various models for current transfer (disordered bonds, brick wall and railway switch) are also reviewed and discussed.

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“…The literature includes several previous experimental observations of power laws of the breakdown form, in studies of HTSCs, 28,[69][70][71][72][73] as well as in granular systems modeled as Josephson junction arrays. 74 In HTSCs, the range of observed exponents a ¼ 2-3 is quite large, though the reasons for this are not clear.…”

Section: Discussionmentioning

confidence: 99%

Percolating transport in superconducting nanoparticle films

Fostner

Nande

Smith

et al. 2017

Journal of Applied Physics

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Nanostructured and disordered superconductors exhibit many exotic fundamental phenomena, and also have many possible applications. We show here that films of superconducting lead nanoparticles with a wide range of particle coverages, exhibit non-linear V(I) characteristics that are consistent with percolation theory. Specifically, it is found that V / ðI À I c Þ a , where a ¼ 2.1 6 0.2, independent of both temperature and particle coverage, and that the measured critical currents (I c) are also consistent with percolation models. For samples with low normal state resistances, this behaviour is observable only in pulsed current measurements, which suppress heating effects. We show that the present results are not explained by vortex unbinding [Berezinskii-Kosterlitz-Thouless] physics, which is expected in such samples, but which gives rise to a different power law behaviour. Finally, we compare our results to previous calculations and simulations, and conclude that further theoretical developments are required to explain the high level of consistency in the measured exponents a.

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Self-similarity in the I-V characteristics of granular YBa₂Cu₃O₇

Abstract: &&ax. The onset of dissipation in the I-V characteristics of granular YBa2Cu307shows clear evidence for a finite critical current. At currents above critical, dissipation in the weak links is only slightly field-and temperaturedependent.

Cited by 15 publications

References 9 publications

Granularity controlled percolative current conduction in YBa₂Cu₃O₇/Ag composite thick films

Granularity controlled percolative current conduction in YBa₂Cu₃O₇/Ag composite thick films

Current transfer and initial dissipation in high- superconductors

Percolating transport in superconducting nanoparticle films

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Self-similarity in the I-V characteristics of granular YBa2Cu3O7

Abstract: &&ax. The onset of dissipation in the I-V characteristics of granular YBa2Cu307shows clear evidence for a finite critical current. At currents above critical, dissipation in the weak links is only slightly field-and temperaturedependent.

Cited by 15 publications

References 9 publications

Granularity controlled percolative current conduction in YBa2Cu3O7/Ag composite thick films

Granularity controlled percolative current conduction in YBa2Cu3O7/Ag composite thick films

Current transfer and initial dissipation in high- superconductors

Percolating transport in superconducting nanoparticle films

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Product

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Self-similarity in the I-V characteristics of granular YBa₂Cu₃O₇

Granularity controlled percolative current conduction in YBa₂Cu₃O₇/Ag composite thick films

Granularity controlled percolative current conduction in YBa₂Cu₃O₇/Ag composite thick films