SPATIALLY RESOLVED MAGNETIC HYSTERESIS IN A YBA2CU3O7-Y CRYSTAL MEASURED BY A HALL-PROBE ARRAY

We report local-magnetic-field measurements near a YBa2Cu3O7-y crystal by a linear array of Hall probes. Two distinct features are observed in the local-field hysteresis H(l) vs H, which are not present in the integrated magnetization measured by a SQUID: (1) a peak in H(l) right after the field reversal that we attribute to the field generated by the current flow in a platelike superconductor, and (2) a position-dependent suppression of H(l) near zero external field which may linked to H(cl). These local measurements suggest a relevant scale for the critical current variation of between 10 and 200-mu-m.