Towards the quantitative theory of the high-Tc Josephson junctions

The possible reasons leading to the reduction of the characteristic voltage V_C of the high-temperature-superconductor (HTS) Josephson Junctions are discussed. It is emphasized that the electron scattering at the superconductor-normal-metal (SN) boundaries plays a decisive role in HTS weak links. Rough estimates of the parameter γ_B describing the SN boundary transparency were obtained. Calculations of the properties of the SNS sandwiches, variable thickness bridges, and SNIS´ tunnel junctions within the framework of BCS-based theories of the Josephson effect have been carried out using models which take into account the low transparency of HTS/N-metal interfaces, and possible values of their I_cR_N product are estimated