Talk by Siegfried Graser – Niels Bohr Institute - University of Copenhagen

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Talk by Siegfried Graser

The interface properties of high-temperature copper oxide superconductors have been of interest for many years, and play an essential role in Josephson junctions, superconducting cables and microwave electronics. In particular, the maximum critical current achievable in high-Tc wires and tapes is well known to be limited by the presence of grain boundaries, regions of mismatch between crystallites with misoriented crystalline axes.

Studies of single artificially fabricated grain boundaries have revealed that the critical current Jc of a grain boundary junction depends exponentially on the misorientation angle. Within a microscopic evaluation based on a construction of fully three-dimensional grain boundaries using molecular dynamics this exponential suppression of the critical current with grain
boundary angle can be theoretically explained.

In this framework it is also possible to identify the build-up of charge inhomogeneities as the dominant mechanism for the suppression of the supercurrent.

Talk by Siegfried Graser