"Pseudogap" State in Superconductors: a.c. Response

Inhomogeneity of the metallic state and, subsequently, a spatial dependence of the critical temperature is a key ingredient of the "pseudogap" phenomenon. One can observe a gap structure above along with anonomalous diamagnetism (splitting of resistive and Meissner transitions). The a.c. properties are drastically different from those for normal models. It is shown that the ReZ?*ImZ* and their difference (Z is the surface impedance, w is the frequency of the a.c. field. Proximity effect between superconducting regions and normal matrix is playing an important role.