LOCAL TIME-DEPENDENT MAGNETIZATION OF SUPERCONDUCTING FILMS IN THE PRESENCE OF A TRANSPORT CURRENT

The time dependence of the normal component of the local flux density Bz(t) was studied using a small Hall sensor placed on a thin film of the high-temperature superconductor YBa2Cu3O7. Following the preparation of the critical state, the time dependence of Bz(t) was studied before, during, and after the application of both positive and negative transport currents. Initial application of current results in an increased relaxation rate. A simple approximation for the relaxation behavior was used to calculate the spatial dependence of the current and flux densities as a function of time using a modified Bean critical-state model that incorporates demagnetization effects in superconducting films. With this model it was possible to account for most of the observed behavior. © 1995 The American Physical Society.