Transport critical currents and grain boundary coupling in high-(Tc) superconductors

摘要

We propose that the transport critical current density for high-(Tc) thin films, bicrystals and bulk ceramics is determined by the magnetic field penetration into the grain boundaries; the grain orientation may not be an important factor. The parameter ((lambda)(sub L)/(lambda)(sub J))(sup 2) can characterize the strength of the grain boundary coupling, which depends mainly on the crystal coherence and connectivity at the boundary area, but not on the crystal orientation.