INTRINSIC JOSEPHSON EFFECTS IN 60-K PHASE YBCO THIN-FILM MESAS

We fabricated c-axis oriented mesas oil YBa2Cu3O7-delta thin films. Co lumnar structures with an area of 20 x 20 mu m(2) and a depth of 0.1 m u m were formed on oxygen deficient films with a critical temperature (T-c) of 64 K or less. The devices showed hysteretic I-V curves withou t any branches. The dependence of the critical current density on the temperature near T, is explained by the Ambegaokar-Baratoff relation.