ELECTRODYNAMICS OF THE ORGANIC SUPERCONDUCTORS KAPPA-(BEDT-TTF)(2)CU(NCS)(2) AND KAPPA-(BEDT-TTF)(2)CU[N(CN)(2)]BR

We have performed measurements of the surface impedance in the normal and superconducting states of the title compounds in the millimeter wave-frequency range (13 cm-1), and have evaluated the complex conductivity for different crystallographic orientations. Above the transition temperature, the materials behave like metals with a scattering rate of approximately 20 cm-1. In the superconducting state the electrodynamics is in good agreement with calculations based on a BCS ground state: while the penetration depth and the coherence length are anisotropic, the superconducting energy gap shows no indications of line nodes. © 1994 The American Physical Society.