Microwave surface resistance in nanostructured high-Tc superconductor films

The impact of artificially created defects nanostructure, formed by implanted dielectric nanoparticles or irradiation defects, on microwave properties of high-Tc superconductor films is analyzed in the framework of phenomenological theory for microwave response of type-II superconductors. We have calculated the surface resistance for such a kind of nanostructured type-II superconductor film and investigated conditions for the emergence of nonlinear response caused by the entrance of microwave-induced vortices in the film's interior through its edges. The obtained results indicate that artificial defect nanostructure in the film's interior formed by point-like or columnar structural defects can significantly improve its microwave characteristics in both the Meissner and mixed states and also increase the threshold for the onset of nonlinear response.