Flux-front motion parallel to CuO2 planes in YBa2Cu3O7-δ observed with a scanning Hall probe

The motion of the flux front in YBa2Cu3O7-δ with the field applied parallel to the layers is studied using a scanning Hall probe. By tracking the peak positions versus field in the remanence, we determine directly the critical current density perpendicular to the layers (Jc=8.3×104 A/cm2 at 4.2 K). The observed critical-current anisotropy (∼500) is much larger than indicated by high-temperature measurements. By scanning the flux profiles in the direction perpendicular to the layers, we find direct evidence that flux motion occurs parallel to the layers. A model that accounts for the observed mountain-pass topography in the remanence is presented.