CONTINUUM ELECTRODYNAMICS OF TYPE-II SUPERCONDUCTORS IN THE MIXED-STATE - THE DC AND AC RESPONSE

The de and ac response of the ideal type-II superconductor in the mixe d state is analyzed in the frame of a continuum electrodynamics, in wh ich all fields are averaged on a scale exceeding the intervortex dista nce. The results of previous calculations are brought together and com pared, while paying special attention to the role of the vortex line t ension and the normal current. The electromagnetic response is studied in the whole range of magnetic fields and frequencies. The possible e ffect of the normal current on vortex motion is discussed. We in this respect that existing theories, where the Lorentz force involves the n ormal current, are not consistent with Onsager relations. Due to vorte x line tension the external fields penetrate into a superconductor as a superposition of two modes with different complex wave numbers (the two-mode electrodynamics). Obtained expressions for the surface impeda nce should permit one to determine the parameters of the theory from t he experiment and to discriminate different models of vortex motion.