Reduced fluxon viscosity in a Josephson junction

Fluxon viscosities within weak Josephson junctions are orders of magnitude smaller than in bulk. Highly mobile fluxons within weak junctions, driven by surface microwave currents, are responsible for the large low-field microwave absorption observed in the granular high-temperature superconductors. While typical fluxon displacements in bulk are in the Angstrom range, displacements in weak Josephson junctions are in the micron range. © 1988.