MICROWAVE HALL-MOBILITY AND CONDUCTIVITY IN CRYSTALS OF VARIOUS (BEDT-TTF) RADICAL SALTS

We report investigations of the microwave transport properties carried out on the organic conductors and superconductors of (BEDT-TTF)-salts: alpha-, alpha-t- and beta-(BEDT-TTF)2I3, alpha-(BEDT-TTF)3(NO3)2 and aleph-(BEDT-TTF)2Cu(NCS)2. The anisotropy and temperature dependence (300 K to 4 K) of the high-frequency conductivity was measured in a microwave cavity at 10.3 GHz. There is low anisotropy in the high conducting plane of the quasi two-dimensional crystals of the (BEDT-TTF)-family, e.g. the (a -->,b-->)-plane in beta-(BEDT-TTF)2I3; perpendicular to this the microwave conductivity is one order of magnitude lower. At room temperature the microwave Hall mobility at 9.5 GHz of the different phases of (BEDT-TTF)2I3 and (BEDT-TTF)3(NO3)2 is 100 to 200 cm2/Vs in the high conducting planes of the crystals. With about 1200 cm2/Vs the high-frequency mobility of the superconductor (BEDT-TTF)2Cu(NCS)2 is similar to the one measured in the (a -->,b -->)-plane of the high-T(c) superconductor YBa2Cu3O7.