Frequency dependence of HTS AC harmonic susceptibility in the Kim-Anderson and collective pinning vortex glass models

By numerically solving the nonlinear magnetic flux diffusion equation, the temperature dependence of the AC magnetic susceptibility have been computed at different frequencies in the framework of the collective pinning vortex glass and of the Kim-Anderson models. In particular the frequency dependence of the amplitude of the third harmonic have been analyzed. Such dependence is determined by the dynamic curvature of the E-J characteristics, normalized to the dynamic resistivity.