FLUX CUTTING IN YBA2CU3O7-DELTA SINGLE-CRYSTALS - EXPERIMENT AND PHENOMENOLOGICAL MODEL

We measured the current-induced loss of vortex correlation in YBa2Cu3O 7-delta crystals using the pseudo-dc-flux-transformer geometry. We fin d that the current density J(cut) at which the top and bottom voltage drops differ is a linear function of temperature, is independent of pi nning, and depends on the thickness of the sample. This thickness depe ndence strongly suggests that the electrical current flows at the surf ace of the sample. The observed behavior with temperature, magnetic fi eld, and thickness is described by a phenomenological model.