Motion of vortices in superconductors

A dissipation-free current can be achieved in a superconductor only when tiny magnetic vortices, which penetrate the superconductor when a magnetic field is applied, are pinned down against current-induced force. To investigate the mechanism by which such vortex pinning occurs, we have made real-time observations of the onset of vortex motion in high-temperature Bi2Sr2CaCu2O8+δ(Bi-2212) superconductors.