Local mapping of dissipative vortex motion
  We explore, with unprecedented single vortex resolution, the dissipation and motion of vortices in a superconducting ribbon under the influence of an external alternating magnetic field. This is achieved by combing the phase sensitive character of ac-susceptibility, allowing to distinguish between the inductive-and dissipative response, with the local power of scanning Hall probe microscopy. Whereas the induced reversible screening currents contribute only inductively, the vortices do leave a fingerprint in the out-of-phase component. The observed large phase-lag demonstrates the dissipation of vortices at timescales comparable to the period of the driving force (i.e. 13 ms). These results indicate the presence of slow microscopic loss mechanisms mediated by thermally activated hopping transport of vortices between metastable states. 
B. Raes, J. Van de Vondel, A. V. Silhanek, C. de Souza Silva, J.   Gutierrez, R. B. G. Kramer, and V. V. Moshchalkov
cond-mat.supr-con