CUED Publications database

Correlation of transport and magnetic critical currents in melt-processed YBa2Cu3O7-δ thick films

Jones, AR and Cardwell, DA and Ingle, NJC and Ashworth, SP and Campbell, AM and Alford, NM and Button, TW and Wellhofer, F and Abell, JS (1994) Correlation of transport and magnetic critical currents in melt-processed YBa2Cu3O7-δ thick films. Journal of Applied Physics, 76. pp. 1720-1725. ISSN 0021-8979

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Abstract

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 J c of the film.

Item Type: Article
Subjects: UNSPECIFIED
Divisions: Div C > Materials Engineering
Depositing User: Cron Job
Date Deposited: 07 Mar 2014 11:40
Last Modified: 08 Dec 2014 02:28
DOI: 10.1063/1.357687