Temperature dependence of critical current in josephson contacts based on YBa2Cu3O7-δ and Bi2Sr2Ca2Cu4Ox

A stationary Josephson effect in contacts based on YBa2Cu3O7-δ (Tc∼90K) and Bi2Sr2Ca2Cu4Ox (Tc∼90K and Tc∼87K) ceramic samples is investigated. In YBa2Cu3O7-δ samples the critical current temperature dependence near Tc is as follows: Ic∼(Tc-T)3/2 which allows one to hypothetically refer the contacts mentioned to S-N-I-N-S type. The contact volt-ampere characteristics based on Bi2Sr2Ca2Cu4Ox at low temperatures are typical of S-I-S-structures. Using Ambegaokar and Baratov theory for Bi2Sr2Ca2Cu4Ox, calculation of temperature dependence of a superconducting gap Δ(T) (1.45≤2Δ(0)/kTc≤3.5) is performed