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SUMMARY:Thermodynamics and critical current density in HTS superconductors
  and beyond  - Jeff Tallon\, Robinson Research Institute\, Victoria Univer
 sity\, New Zealand.
DTSTART:20140625T101500Z
DTEND:20140625T111500Z
UID:TALK52268@talks.cam.ac.uk
CONTACT:Helen Verrechia
DESCRIPTION:With an HTS manufacturing business* spun out from our fundamen
 tal and applied R&D programmes over the past 27 years\, we are particularl
 y conscious of the ongoing need to drive up the critical current density\,
  Jc\, and determine its fundamental limits. This talk examines the relatio
 nship between thermodynamics and Jc both in the presence and absence of ex
 ternal applied fields. These two limits result in quite different phenomen
 ology. In the self-field limit (Hext = 0) we find that Jc is limited by fu
 ndamental parameters and this provides a means to directly measure the Lon
 don penetration depth\, (T)\, from Jc(T)\, along with the symmetry and 
 magnitude of the order parameter. The ideas developed are confirmed by the
  effects of impurity substitution on Jc(T) which have a distinctive charac
 ter due to the rapid suppression of superfluid density due to impurity sca
 ttering. The ideas are also confirmed by applying to 31 different supercon
 ducting systems\, including s-wave and d-wave\, type I and type II. By com
 bining with in-field Jc data we can also extract both the magnitude and T-
 dependence of the order parameter.
LOCATION:Mott Seminar Room (531)\, Cavendish Laboratory\, Department of Ph
 ysics
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