SURFACE IMPEDANCE STUDIES ON THE ELECTRODYNAMIC RESPONSE OF ORGANIC SUPERCONDUCTORS

We have performed detailed measurements of the surface impedance in th e normal and superconducting state of kappa-(BEDT-TTF)(2)Cu(NCS)(2) in the millimeter wave frequency range (1 cm(-1) to 3 cm(-1)), and have evaluated the complex conductivity for different crystallographic orie ntations. Above the transition temperature, the material behaves like a metal with a scattering rate of approximately 20 cm(-1). In the supe rconducting state the electrodynamics of both materials is in good agr eement with calculations based on a BCS ground state: the penetration depth is temperature independent for T --> 0; while the penetration de pth and the coherence length are strongly anisotrop, the superconducti ng energy gap shows no indications of line nodes.