Critical currents and irreversibility lines in HgBa2(Ca1-xSrx)2Cu3O8+δ and Hg0.5Tl0.5Ba2(Ca1-xSrx)2 Cu3O8+δ

K. H. Yoo, N. H. Hur, Y. K. Park, J. C. Park, Y. Y. Song, S. C. Yu

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Abstract

We have investigated the temperature dependence and applied magnetic-field dependences of critical current densities Jc(H, T) and the irreversibility lines Hirr(T) obtained from the magnetization measurements in HgBa2(Ca1-xSrx)2Cu3O8+δ and Hg0.5Tl0.5Ba2(Ca1-xSrx)2Cu3O8+δ. Jc(H, T) and Hirr(T) of Hg0.5Tl0.5Ba2(Ca1-xSrx)2Cu3O8+δ are found to be higher than those of HgBa2(Ca1-xSrx)2Cu3O8+δ, indicating that the Tl substitution at Hg sites provides additional flux pinning. Jc(H, T) has been analyzed using the flux-creep model. Jc(H, T) in magnetic fields above 1 T is well described by the flux-creep model. However, the thermal activation energy estimated by fitting the data to the flux-creep model shows different behaviors above and below about 65 K for both HgBa2(Ca1-xSrx)2Cu3O8+δ and Hg0.5Tl0.5Ba2(Ca1- xSrx)2Cu3O8+δ. Also, in Hirr(T) a crossover from a power-law temperature dependence above 65 K to a more rapid dependence below 65 K is observed in both samples. Although the origin of such a crossover in Hirr(T) and Jc(H, T) is not clear, the two phenomena are considered to be closely related.

Original languageEnglish
Pages (from-to)21-25
Number of pages5
JournalPhysica C: Superconductivity and its applications
Volume231
Issue number1-2
DOIs
Publication statusPublished - 1994 Sep 20

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering

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