EVIDENCE OF CURRENT-NOISE HYSTERESIS IN SUPERCONDUCTING YBA2CU3O7-DELTA SPECIMENS IN A MAGNETIC-FIELD

Current noise observed on YBa2Cu3O7-delta ceramic superconductors, brought to a resistive state by the application of a magnetic field, is shown to be very different in amplitude when the same resistance value is obtained by either increasing or decreasing the field. A tentative explanation of this hysteretic effect on current noise in terms of a model of superconducting islands separated by resistive, noise-generating boundaries, whose structure is hysteretically field dependent, is reported. The possibility of using the noise to get information on the internal structure of the "strong" and "weak" superconducting regions is suggested.