Influence of surface barriers on vortex dynamics in Bi2Sr2CaCu2O8+delta whiskers

Bi2Sr2CaCu2O8+delta whiskers are single crystals with highly regular surfac es and few extended defects, making them excellent model systems for studyi ng the role of surfaces in magnetization, Furthermore, they can be elastica lly bent without losing their superconducting properties, making them poten tially important technological materials,,ve have made a detailed investiga tion of their magnetic properties using miclonsized Hall probe arrays and s how that surface effects play a dominant role in controlling the vortex dyn amics, particularly in the moderate to high temperature regime. Local magne tic induction cycles exhibit the asymmetric behaviour characteristic of sur face barriers and when the whiskers are slowly field cooled, sharp jumps ar e observed, The systematic behaviour of these jumps leads us to speculate t hat they represent sudden configurational rearrangements as a result of the interplay between vortex-surface barrier and vortex-vortex interactions.