Factors Influencing Critical Current Densities in High T sub c Superconductors

  • Fisanick G.

A key requirement for many practical application of the new class of high T sub c superconductors is the ability to sustain high current densities in the presence of magnetic fields. The new materials present two substantially different behaviors. For Ba sub 2 YCu sub 3 O sub 7 critical current behavior of polycrystalline material is dominated by intergranular transport. We will review a model for transport involving the effects of correlation of defects with grain boundary orientation, the presence of impurities at the grain boundaries, measurements of tunneling characteristics through the boundaries, and the effect of grain alignment on critical current. The case is substantially different in the 84K superconducting phase Bi sub (2.2) Sr sub 2 Ca sub (0.8) Cu sub 2 O sub (8+delta) where there is a very strong dependence of critical current densities at 30-84K on magnetic field for single crystals. There is a lack of threshold behavior in the I-V characteristics in finite applied fields larger than H sub (c1) (T) which is attributed to flux creep. This suggests that in the Bi material there is insufficient pinning of vortices in the intrinsic material to prevent them moving in the presence of an applied transport current, causing dissipation. The implications of these various factors on potential applications of these materials will be discussed.

Recent Publications

January 01, 2019

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  • Bron M.
  • Chute M.
  • Evans H.
  • Lalmas M.
  • Redi M.
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© 2017 International World Wide Web Conference Committee (IW3C2), published under Creative Commons CC BY 4.0 License. Many of today's websites have recognised the importance of mobile friendly pages to keep users engaged and to provide a satisfying user experience. However, next to the experience provided by the sites themselves, ...

January 01, 2019

Analyzing uber's ride-sharing economy

  • Aiello L.
  • Djuric N.
  • Grbovic M.
  • Kooti F.
  • Lerman K.
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© 2017 International World Wide Web Conference Committee (IW3C2), published under Creative Commons CC BY 4.0 License. Uber is a popular ride-sharing application that matches people who need a ride (or riders) with drivers who are willing to provide it using their personal vehicles. Despite its growing popularity, there exist ...

January 01, 2019

The paradigm-shift of social spambots: Evidence, theories, and tools for the arms race

  • Cresci S.
  • Petrocchi M.
  • Pietro R.
  • Spognardi A.
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© 2017 International World Wide Web Conference Committee (IW3C2), published under Creative Commons CC BY 4.0 License. Recent studies in social media spam and automation provide anecdotal argumentation of the rise of a new generation of spambots, so-called social spambots. Here, for the first time, we extensively study this novel ...