Nature of the Josephson barrier in electron-beam-written YBa2Cu3O7-? junctions

We analyze the temperature (T) dependence of the normal-state resistance Rn and critical current Ic in field-emission-gun electron-beam-written YBa2Cu2O7-? Josephson junctions from the electrode transition temperature (Tc) to 1.5 K. From a theoretical fit to Ic(T) and Rn(T) we find that the Josephson barrier exhibits properties of a small Fermi-surface area, dirty normal metal near its maximum metallic resistivity. Within conventional superconductor-normal-superconductor theory the barrier is 3.5 mean-free-paths long at Tc, with a normal-metal coherence length at Tc intermediate between the clean and dirty limits.