Critical current across grain boundaries in melt-textured YBa{sub 2}Cu{sub 3}O

Journal Article · Mon Oct 01 04:00:00 EDT 2001 · Physical Review B

DOI:https://doi.org/10.1103/PhysRevB.64.144507· OSTI ID:40277683

Claus, H; Welp, U; Zheng, H; Chen, L; Paulikas, A P; Veal, B W; Gray, K E; Crabtree, G W

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.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL
• Sponsoring Organization: (US)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 40277683
• Journal Information: Physical Review B, Journal Name: Physical Review B Journal Issue: 14 Vol. 64; ISSN 0163-1829
• Publisher: The American Physical Society
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CRITICAL CURRENT
CURRENT DENSITY
GRAIN BOUNDARIES
MAGNETIC FIELDS
MAGNETIC MOMENTS
MONITORING
SHIELDING
TRANSPORT
VOLTAGE DROP
WELDING