Josephson characteristics in a-axis oriented YBa2Cu3O7-δ/PrBa2Cu3O7-δ'/YBa2Cu3O7-δ junctions

A sandwich-type all-oxide Josephson junction consisting of an a-axis oriented YBa2Cu3O7−δ/PrBa2Cu3O7−δ′/YBa2Cu3O7−δ structure has been realized and its Josephson characteristics experimentally investigated. Almost all the fabricated junctions showed the Josephson characteristics, including a resistively shunted junction (RSJ)-like current-voltage characteristic and a Fraunhofer-like magnetic-field dependence of the critical current. The obtained maximum values of the critical-current density jc and the IcRn value were 110 A/cm2 and 80 μV, respectively, for a 50-nm-thick PBCO interlayer at 3 K. Besides, the temperature dependencies of the critical current and the normal resistance were measured. Ic was proportional to exp(− aT1/2), where a is a constant.