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Abstract

Dielectric resonances in the microwave region 16 to 40 GHz have been observed in single crystals of the highly anisotropic material TTF-TCNQ below 25°K. The application of open-circuit boundary conditions to the dielectric resonator problem is shown to be inappropriate for this material and a tractable alternative theory, which takes external fields into account, is presented. Using this theory, the dielectric modes were analyzed at 4.2°K to obtain the complex dielectric constant εb along the crystallographic b-axis. For four samples studied in detail, the average values for the real and imaginary parts of the dielectric constant are found to be 4200 and 16 respectively at 25 GHz. A frequency dependence of ε’b is found; however, it is not clear whether this frequency dependence is intrinsic to the samples or is due to the approximate nature of the solution. No frequency dependence of ε”b was observed.