Correlation of transport and magnetic critical currents in melt-processed YBa2Cu3O7−δ thick films
Jones, A. R. ; Cardwell, D. A. ; Ingle, N. J. C. ; Ashworth, S. P. ; Campbell, A. M. ; Alford, N. McN. ; Button, T. W. ; Wellhofer, F. ; Abell, J. S.
[S.l.] : American Institute of Physics (AIP)
Published 1994
[S.l.] : American Institute of Physics (AIP)
Published 1994
| ISSN: |
1089-7550
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| Source: |
AIP Digital Archive
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| Topics: |
Physics
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| Notes: |
Transport critical current measurements have been carried out on melt-processed thick films of YBa2Cu3O7−δ on yttria-stabilized zirconia in fields of up to 8 T both within grains and across grain boundaries. These measurements yield Jc values of ∼3000 A cm−2 at 4.2 K and zero magnetic field and 400 A cm−2 at 77 K and zero magnetic field, taking the entire sample width as the definitive dimension. Optical and scanning electron microscopy reveals that the thick-film grains consist typically of a central "hub'' region ∼50 μm in diameter, which is well connected to radial subgrains or "spokes'' which extend ∼1 mm to define the complete grain structure. Attempts have been made to correlate the transport measurements of inter- and intra-hub-and-spoke (H-S) critical current with values of this parameter derived previously from magnetization measurements. Analysis of the transport measurements indicates that current flow through H-S grains is constrained to paths along the spokes via the grain hub. Taking the size of the hub as the definitive dimension yields an intra-H-S grain Jc of ∼60 000 A cm−2 at 4.2 K and 0 T, which is in reasonable agreement with the magnetization data. Experiments in which the hub is removed from individual grains confirm that this feature determines critically the Jc of the film.
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| Type of Medium: |
Electronic Resource
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| URL: |