THE GIANT SHORT-TIME DECAY OF PERSISTENT CURRENTS IN Y1BA2CU3O7-DELTA AT 77-K

Using a home-made pulse magnetometer, the decay of the persistent supercurrent in Y1Ba2Cu3O7-delta (Y1:2:3) has been measured from 10(-4) to 10(5) s. There is a three-fold nonlogarithmic decrease in the persistent current from 10(-4) to 10 s at 77 K, suggesting that the traditionally measured critical current density (J(c)) is only a small remnant of the fast reduced supercurrent. The nonlogarithmic decay suggests a significant negative curvature in the corresponding ln V-ln I plot and fits with the collective pinning/superconductive glass model qualitatively.