Electrodynamic properties of a superconducting Y-Ba-Cu-O film in the submillimeter wave length range

The dynamic conductivity σi(v) and permittivity ε'(v) spectra of a superconducting YBa2Cu3I7-x film are measured directly at frequencies v=8-32 cm-1 which are smaller than the energy of the superconducting gap. In the normal phase ε'(v, T) and σi(v, T) reveal a metallic behaviour with a characteristic plasma frequency ∼ 3200 cm-1 and damping ∼ 380-1. In the superconducting phase the variation of ε(v,T) is in accordnace with the classical concepts regarding the low-frequency electrodynamics of superconductors. The polycrystalline structure of the film substantially distorts the behavior of the dynamic conductivity in the superconducting phase. The temperature dependences of the superconducting electrons concentration, penetration depth of radiation and real and imaginary parts of the surface impedance are calculated