Towards “Ideal” High-Tc Josephson Junction: [100]-tilt YBa2Cu3O7-x Bicrystal Boundary

Based on structural, electrical and THz characterization of [100]-tilt YBa2Cu3O7-x bicrystal junctions, criteria have been formulated for the “ideal” high-Tc Josephson junction: a single crystallographic facet for each high-Tc electrodes at the bicrystal boundary, optimal oxygen content inside the boundary, IcRn-values up to 10 mV, phonon-induced structures on the I-V curves at the voltages from 4 to 12 mV at T = 4.2 K and RSJ-like I-V curves at T ≥ 50 K within an accuracy of 1%. When compared with the “ideal” low-Tc junctions, the “ideal” high-Tc junctions are characterized by the IcRn-values of around 4-5 times below Ambegaokar-Baratoff value πΔ(0)/2 and strong interaction between Josephson oscillations and optical phonons of electrodes.