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Fluctuation Conductivity of RE1−2x Ca x M x Ba2Cu3O7−δ (RE=Nd, Y and M=Pr, Th) Superconductors

  • S. R. Ghorbani
  • M. Rahmati Tarki
Original Paper

Abstract

Polycrystalline samples of RE1−2x Ca x M x Ba2Cu3O7−δ with RE=Nd, Y and M=Pr, Th (with 0.0≤x≤0.10), superconductors were prepared by the standard solid-state method. Resistivity was measured as a function of temperature and doping concentration x. Excess conductivity was analyzed using the modified Lawrence-Doniach (LD) expressions. The fluctuation regions, crossover temperatures, coherence lengths, and effective layer thickness were obtained and the values were compared for both samples. For both samples, it was found that with increasing doping, the crossover temperatures were reduced, while the coherence length decreased. The upper critical field and critical current density were increased with increasing doping concentration due to the introduction of disorder and the enhancement of flux pinning by charge neutral doping. Furthermore, the coherence lengths of the Nd-based samples are larger than that for the Y-based samples by a factor 2. It was found that the value of critical current density in Nd(CaPr)-123 is higher than Y(CaTh)-123, from which it is suggested that CaPr doping is more effective than CaTh doping.

Keywords

Superconductivity Fluctuation Excess conductivity 

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Copyright information

© Springer Science+Business Media New York 2013

Authors and Affiliations

  1. 1.Department of PhysicsFerdowsi University of MashhadMashhadIran
  2. 2.Department of PhysicsHakim Sabzevari UniversitySabzevarIran

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