Correlation of transport and magnetic critical currents in melt‐processed YBa2Cu3O7−δthick films
| Autor: | N.McN. Alford, A.M. Campbell, J.S. Abell, Anya R. Jones, F. Wellhofer, S. P. Ashworth, Tim W. Button, N. J. C. Ingle, David A. Cardwell |
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| Rok vydání: | 1994 |
| Předmět: | |
| Zdroj: | Journal of Applied Physics. 76:1720-1725 |
| ISSN: | 1089-7550 0021-8979 |
| Popis: | 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 s... |
| Databáze: | OpenAIRE |
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