Progress in Superconductivity

The Korean Superconductivity Society (한국초전도학회)
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Effect of Calcium Doping in Low Angle Grain Boundaries of $YBa_2Cu_3O_{7-\delta}$ on Textured Metal Substrates

  • Kang, B.W. (National Creative Research Initiative Center for Superconductivity and Department of Physics Pohang University of Science and Technology) ;
  • A. Goyal (Oak Ridge National Laboratory) ;
  • F.A. List (Oak Ridge National Laboratory) ;
  • D.K. Christen (Oak Ridge National Laboratory) ;
  • H. R. Kerchner (Oak Ridge National Laboratory) ;
  • S. Sathyamurthy (Oak Ridge National Laboratory) ;
  • Lee, D.F. (Oak Ridge National Laboratory) ;
  • Martin, P.M. (Oak Ridge National Laboratory) ;
  • Koreger, D.M. (Oak Ridge National Laboratory)
  • Published : 2002.01.01
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Abstract

We report the effect of Ca doping in $YBa_2Cu_3O_{7-\delta}$ (YBCO) thin films grown on the Rolling- Assisted, Biaxially Textured Substrates (RABiTS) with the architecture of $CeO_2/YSZ/CeO_2/Ni$. Critical currents of bilayer and trilayer structures of $YBCO/Y_{0.7}Ca_{0.3}Ba_2Cu_3O_{7-\delta}$/(YCaBCO) as well as undoped YBCO for comparison have been measured in a wide range of temperatures and fields. For $6-8^{\circ}$ grain boundaries, 30% Ca-doping in bilayer structure enhances $J_c$ as high as 35%. The enhancement is larger at low temperatures and at magnetic fields. On the other hand, 30% Ca-doping in trilayer structure reduces $J_c$ as high as 60%. Combined with slightly lower $T_c$, this indicates that Ca is overdoped in this structure and degrades GBs.

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