On the microwave response of thin superconducting films with trapped magnetic flux

Abstract

Basing on the phenomenological model of the microwave response of thin superconducting films with trapped magnetic flux elaborated in Luzhbin et al (2005) Supercond. Sci. Technol. Vol.18, pp.1112-7, detailed analysis of the ac linear response of a superconducting strip-line resonator cooled down in FC and ZFC regimes is presented. Special emphasis on a nonuniform distribution of the trapped vortices and on the magnetic field and temperature dependence of the phenomenological model parameters such as critical current density, vortex pinning and viscous motion coefficients is made. For a ZFC case realistic trapped magnetic field distribution based on the critical-state model for a vortex penetration is used. Within the framework of the used model the unusual multi-peak dependence of the surface resistance of HTS films observed experimentally is explained as well as clarified conditions for its appearance.