2005, 2001, English, Thesis edition: Critical Current Anisotropy in High Temperature Superconductors Durrell, John Hay

User activity

Share to:
 
Bookmark: http://trove.nla.gov.au/version/70523
Physical Description
  • 41231855 bytes, 8069707 bytes, application/​zip, application/​pdf
  • Thesis
Published
  • 2005-06-10T15:37:51Z
  • 2001-04
Language
  • English

Edition details

Title
  • Critical Current Anisotropy in High Temperature Superconductors
Author
  • Durrell, John Hay
Published
  • 2005-06-10T15:37:51Z
  • 2001-04
Physical Description
  • 41231855 bytes, 8069707 bytes, application/​zip, application/​pdf
  • Thesis
Subjects
Notes
  • The associated data is in a 'raw' form and is lacking some contextual data. Please do not republish any of the data from the zip file without reference to the author.
  • After nearly 15 years of research effort, High Temperature Superconductors (HTS) arefinding a wide range of practical applications. A clear understanding of the factors controllingthe current carrying capacity of these materials is a prerequisite to their successfultechnological development. The critical current density (Jc) in HTS is directly dependent onthe structure and pinning of the Flux Line Lattice (FLL) in these materials.This thesis presents an investigation of the Jc anisotropy in HTS. The use of thin films grownon off c-axis (vicinal) substrates allowed the effect of current directions outside the cuprateplanes to be studied. With this experimental geometry Berghuis, et al. (Phys. Rev. Lett. 79,12, pg. 2332) observed a striking flux channelling effect in vicinal YBa2Cu3O7-δ (YBCO)films. By confirming, and extending, this observation, it is demonstrated that this is anintrinsic effect. The results obtained, appear to fit well with the predictions of a field angledependent cross-over from a three dimensional rectilinear FLL to a kinked lattice of stringsand pancakes. The pinning force density for movement of strings inside the cuprate planes isconsiderably less than that on vortex pancake elements. When the FLL is entirely string-likethis reduced pinning leads to the observed channelling minima. It is observed that anti-phaseboundaries enhance the Jc in vicinal YBCO films by strongly pinning vortex strings.The effect on the FLL structure cross-over of increasing anisotropy has been elucidated usingde-oxygenated vicinal YBCO films. Intriguingly, the counter intuitive prediction that therange of applied field angle for which the kinked lattice is fully developed reduces withincreasing anisotropy, appears to be confirmed.Although vortex channelling cannot be observed in c-axis YBCO films, the pinning forcedensity for vortex string channelling has been extracted by observing string dragging. Bystudying the effect of rotating the applied field at a constant angle to the cuprate planes, it ispossible to observe the cross-over into the string pancake regime in c-axis films. In the 3Dregion, the observed behaviour is well explained by the anisotropic Ginzburg-Landau model.Measurements were also made on thin films of the much more anisotropic Bi 2Sr2CaCu2O8+xmaterial, grown on vicinal substrates. The absence of any flux channelling effect and clearadherence to the expected Kes-Law behaviour in the observed Jc characteristics does notprovide evidence for the existence of the predicted ‘crossing lattice’ in Bi 2Sr2CaCu2O8+x .
  • Materials Science and Metallurgy, University of Cambridge 2001
Language
  • English
Contributed by
OAIster

Get this edition

  • Set up My libraries

    How do I set up "My libraries"?

    In order to set up a list of libraries that you have access to, you must first login or sign up. Then set up a personal list of libraries from your profile page by clicking on your user name at the top right of any screen.

  • All (1)
  • Unknown (1)
None of your libraries hold this item.
None of your libraries hold this item.
None of your libraries hold this item.
None of your libraries hold this item.
None of your libraries hold this item.
None of your libraries hold this item.
None of your libraries hold this item.
None of your libraries hold this item.

User activity


e.g. test cricket, Perth (WA), "Parkes, Henry"

Separate different tags with a comma. To include a comma in your tag, surround the tag with double quotes.

Be the first to add a tag for this edition

Be the first to add this to a list

Comments and reviews

What are comments? Add a comment

No user comments or reviews for this version

Add a comment