Modeling of nonlinear surface impedance of high-Tc superconductors using an exponential vortex penetration model

We have modeled surface impedance of YBa₂Cu₃O₇−δ thin films, using an exponential dependence on an applied rf magnetic field. For verification of the model we compared simulation results with experimental data of Nguyen et al. [2] and of Hein [14] at differing temperatures, frequencies and rf power levels. Obtained temperature dependence of the model fitting coefficients exhibited the same character in both cases