Magnetoresistance, transport noise and granular structure in polycrystalline superconductors

Abstract

In this work we present a theoretical study on the magnetic field dependence of the electrical resistance R (Ba) and the transport noise (TN) in a high‐Tc polycrystalline superconductors. In the model, we have considered the ceramic superconductor as a series‐parallel array of Josephson devices and the intergranular magnetic field is described within the framework of the intragranular flux‐trapping model. The obtained results qualitatively reproduce the hysteretic behavior of the R (Ba) dependence in increasing and decreasing applied magnetic fields. We have found that the hysteretic behavior in the R (Ba) dependence changes appreciably if different statistical distributions of the geometric factors of grains are used. In addition, such changes are also reflected in the TN, which is produced by the electric current rearrangement in the array with increasing applied magnetic fields. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Experimental and theoretical study of transport properties in uniaxially pressed (Bi,Pb)2Sr2CaGarcía-Fornaris1, Muné2, Suzuki3 et al. 2010Physica C: SuperconductivitySelf Cite3000View full textAdd to dashboardCite

“…Following the results of Refs. [4,5], we have assumed that the mean value of the geometric factor of the grains in Bi-2223 ceramic samples is G % 0. By using a computational program we were able to generate a two-dimensional series-parallel array of Josephson devices.…”

“…Polycrystalline high-T c superconductors can be regarded as a two-dimensional series-parallel array of Josephson devices [4]. We assumed that for each device in the network, the critical current density j c as a function of both the applied magnetic field B a and the grain-boundary angle a can be described by:…”

“…Within this context, the main contribution of the paper is to provide a more adequate model to describe the magnetoresistance and the transport noise features of polycrystalline high-T c superconductors. This has been made by considering the grain-boundary angle distributions (GBAD) instead of the geometric factor of the grains as proposed previously [4].…”

“…[4] to described both the magnetoresistance RðB a Þ and the transport noise TN by considering the grain-boundary angle distribution GBAD of the samples. The parameters of the GBAD were obtained by fitting experimental curves of the magnetoresistance and transport noise measured in polycrystalline samples of Bi 1:65 Pb 0:35 Sr 2 Ca 2 Cu 3 O 10þd subjected to different uniaxial compacting pressures.…”

“…Recently, a theoretical approach for describing the magnetic field dependence of the electrical resistance RðB a Þ and the transport noise (TN) in high-T c polycrystalline superconductors was developed [4]. The superconducting ceramics are considered as a series-parallel array of Josephson devices and the intergranular magnetic field, B i , described in terms of the intragranular flux-trapping model.…”