CONTROLLED REDUCTION OF CRITICAL-CURRENT DENSITIES IN YBCO THIN-FILMS

The reduction of critical currents in HTS films has proven to be of pr imary importance for the fabrication of devices sensitive to small app lied magnetic fields (<100 Gauss). In this work, we report on a proces s we have developed for the controlled reduction of critical current d ensities (J(c)'s) on thin films of YBCO. By diffusing SiO in photolith ographically defined microbridges YBCO, we have been able to obtain a reduction of up to three orders of magnitude of the J(c)'s of our samp les in a reproducible way, without significantly lowering their transi tion temperatures. The microbridges treated in this way show an increa sed sensitivity to externally applied magnetic fields. This indicates that our method for reducing the J(c)'s of HTS films is a good candida te for the fabrication of flux flow devices. Preliminary experimental results on flux flow devices are discussed.