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Author Claus, H. ♦ Welp, U. ♦ Zheng, H. ♦ Chen, L. ♦ Paulikas, A. P. ♦ Veal, B. W. ♦ Gray, K. E. ♦ Crabtree, G. W.
Sponsorship (US)
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Publisher The American Physical Society
Language English
Subject Keyword CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS ♦ CRITICAL CURRENT ♦ CURRENT DENSITY ♦ GRAIN BOUNDARIES ♦ MAGNETIC FIELDS ♦ MAGNETIC MOMENTS ♦ MONITORING ♦ SHIELDING ♦ TRANSPORT ♦ VOLTAGE DROP ♦ WELDING
Abstract We determine the critical current J{sub cB} of grain boundaries fabricated by ''welding'' of melt-textured YBCO with various degrees of ab-plane misalignment. J{sub cB} is determined by monitoring the magnetic moment due to persistent shielding currents, which were induced in rings containing two sections of a single grain boundary. The voltage drop across the junctions is estimated to be below 10{sup -12} V, much smaller than in typical transport measurements. As the temperature or magnetic field is increased, an abrupt decrease (kink) is observed in the magnetic moment of the ring when the induced shielding current in the ring exceeds the critical current across the boundaries. The kink signals that flux has begun to penetrate through the grain boundaries into the bore of the ring. This behavior is confirmed by magneto-optical imaging. We observe that grain boundaries with [001] tilt mismatch angles up to 5{sup o} have critical current densities in excess of 10{sup 4} A/cm{sup 2}, comparable to the bulk current density. At larger mismatch angles, the critical current rapidly decreases with increasing angle. The qualitative behavior of J{sub cB} as function of temperature, magnetic field, and misorientation angle is similar to that observed YBCO grain boundaries manufactured by other methods.
ISSN 01631829
Educational Use Research
Learning Resource Type Article
Publisher Date 2001-10-01
Publisher Department Argonne National Laboratory (ANL), Argonne, IL
Publisher Place United States
Journal Physical Review B
Volume Number 64
Issue Number 14
Organization Argonne National Laboratory (ANL), Argonne, IL


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