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Transport critical currents and flux pinning in melt-grown YBa2Cu3O7−δ

✍ Scribed by Y. Yang; C. Beduz; Z. Yi; R.G. Scurlock

Publisher
Elsevier Science
Year
1992
Tongue
English
Weight
579 KB
Volume
199
Category
Article
ISSN
0921-4534

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✦ Synopsis

The critical current and flux pinning properties of melt grown YBa2Cu3OT_6 bulk material were investigated by transport measurements and V-I characteristics. A J¢ of 16 000 A cm -2 in zero field and 3000 A cm -2 in 1 T at 77 K was obtained using a criterion of 3.3 I~V cm-~. No features of granularity could be detected as Jc showed no hysteresis with increasing or decreasing field. By considering a distribution of activation energy Uo together with the correlation volume of flux bundles V¢ and the pinning range rp, the measured V-1 characteristics in the flux creep regime were found to be consistent with that of thermally activated flux flow (TAFF). The temperature and field dependence of the derived V¢rp points to a collective pinning mechanism by point defects. The depinning current J¢, one to tow orders of magnitude higher than the transport Jc, was also obtained by using the Uo and V¢rp deduced from the V-I characteristics.

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