Physica C-Superconductivity and its applications vol:341 pages:965-968
The pinning of vortices is studied in a superconducting Pb film with a regular array of submicron dots (Co dots with in-plane magnetization and Co/Pt dots with out-of-plane magnetization) or antidots. Matching anomalies are observed in the critical current and magnetization behavior at integer and rational multiples of the first matching field, corresponding to stable vortex configurations. The pinning force of Co dots with a single-domain state is enhanced compared to multi-domain dots. For Co/Pt dots with out-of-plane magnetisation a clear asymmetry is present in the magnetisation curves due to the direct interaction of the vortices with the magnetic moment of the dots. In superconducting films with a square array of antidots, Shapiro voltage steps are observed in the voltage-current characteristics in the presence of rf-radiation. These steps clearly reveal the presence of mobile interstitial vortices coexisting with immobile vortices strongly pinned at the antidots.