Grain boundary dissipation in high-{Tc} superconductors
Thin-film and bulk [001] tilt bicrystal grain boundaries (GBs) in YBa{sub 2}Cu{sub 3}O{sub 7} exhibit a strong dependence of critical current density, J{sub c} on misorientation angle. What was initially difficult to understand was the 30x smaller J{sub c} in bulk GBs which are microscopically more perfect. The authors review an explanation of this zero-field data, which is based on the pinning of Josephson vortices by the meandering found in thin-film GBs. In addition, there is evidence that J{sub c} of GBs does not drop as quickly with applied magnetic field as expected by simple Josephson junction models. The long-wavelength pinning potential due to meandering is less effective at high fields, but Gurevich and Cooley (GC) proposed a new mechanism for an enhanced GB J{sub c} arising from pinned Abrikosov vortices in the banks of a GB which present a static, quasiperiodic pinning potential to pin GB vortices. They find a peak in J{sub c} and an unusual hysteresis which give considerable support to the GC concept. In low fields, the GBs exhibit a larger J{sub c} for field cooling, which is opposite to the usual hysteresis but agrees with GC due to the larger Abrikosov vortex density in the banks. Magnetization data on the same sample are consistent including the identification of the irreversibility field.
- Research Organization:
- Argonne National Lab., IL (US)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 754471
- Report Number(s):
- ANL/MSD/CP-100401
- Country of Publication:
- United States
- Language:
- English
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