INVESTIGATION OF FLUX-CREEP IN HIGH-T-C-SUPERCONDUCTORS USING HALL-SENSOR-ARRAY

The details of a new method for studying thermally activated flux cree p in thin superconducting samples is described. The method employs a l inear array of microscopic Hall sensors to measure the time and spatia l dependence of the magnetic induction across the sample. These data a re analyzed on the basis of the local rate equation for thermally acti vated flux motion, taking into account both the in-plane and out-of-pl ane components of the induction field. Following this analysis, flux c reep parameters, such as the flux-line current density, flux-line aver age velocity, and the activation energy for flux creep, can be directl y determined as a function of position and time. New experimental data in a superconducting Nd1.85Ce0.15CuO4-delta crystal demonstrate this method. (C) 1997 American institute of Physics.