ENHANCED AC CONDUCTIVITY BELOW T(C) IN FILMS OF YBA2CU3O7-DELTA

In superconductors, close to the transition temperature, a peak in the real part of the conductivity sigma1(T,omega), can appear for several reasons. We show that even in the two-fluid model, a peak is present when there is a distribution of T(c)'s in the sample. A parasitic inductance modifies the features of a peak considerably, but in general does not generate a peak by itself. We illustrate this by four-contact-impedance measurements on thin (3000-angstrom) films of YBa2Cu3O7-delta in the kHz regime.