Controllable reduction of critical currents in YBa2Cu3O7−δ films

Abstract

The critical currents in high quality thin films of the high T_c superconductor, YBa₂Cu₃O_7−δ, can be controllably reduced by orders of magnitude using ion irradiation. This reduction in critical current occurs without substantial decrease in T_c or increase in room‐temperature resistivity. Using this technique, we have fabricated weak links that exhibit an ac Josephson effect at 77 K.