Current redistribution effects in superconducting microwave measurements

Microwave measurements, performed on high temperature Superconducting (HTS) films, have evidenced anomalous features in the temperature dependence of some fundamental parameters such as the surface impedance (Z(S)) the penetration depth (lambda) and the complex conductivity (sigma). In particular, anomalous peaks have been observed in the temperature region just below the critical temperature T-C. In high temperature superconductors (HTSs), these behaviours have been interpreted in terms of different theoretical models, concerning the nature of superconducting quasi-particles and their intrinsic pairing mechanisms. The aim of this paper is to stress the importance Of Current redistribution phenomena which take place in microwave measurements and are able to give rise to similar anomalous effects. By performing specific simulations on planar resonators and following standard procedures in the data extraction, unconventional temperature dependences of Z(S), lambda and sigma have been reproduced.