Magneto-optical investigation of flux penetration in a superconducting ring - art. no. 144505

Using advanced magneto-optics, the field and current distributions in super conducting thin film YBa2Cu3O7 rings in an externally applied magnetic fiel d are studied experimentally. The observations are in close agreement with numerical calculations. During the initial flux penetration and field rever sal a highly nonuniform current distribution is observed. In particular, co ncentric counterrotating current loops occur during field reversal. We expl ore implications of these results for the determination of critical current s and penetration fields from bulk magnetization measurements.