Abstract
The low-frequency response of type II superconductors to electromagnetic excitations is the result of two contributions: the Meissner currents and the dynamics of quantum units of magnetic flux, known as vortices. These vortices are threedimensional elastic entities, interacting repulsively, and typically immersed in an environment of randomly distributed pinning centers. Despite the continuous progress made during the last decades, our current understanding of the complex dynamic behavior of vortex ensembles relies on observables involving a statistical average over a large number of vortices. Global measurements, such as the widespread acsusceptibility technique, rely on introducing certain assumptions concerning the average vortex motion thus losing the details of individuals. Recently, scanning susceptibility microscopy (SSM) has emerged as a promising technique to unveil the magnetic field dynamics at local scales. This chapter is aimed at presenting a pedagogical and rather intuitive introduction to the SSM technique for uninitiated readers, including concrete illustrations of current applications and possible extensions.
