Field and frequency dependent transport in the two-dimensional organic conductor α-(BEDT-TTF)2I3

Abstract

We studied the electrodynamic response of α-(BEDT-TTF)2I3 in a wide range of frequency, covering microwave and millimeter wave frequencies as well as the optical spectral range, and found a frequency dependent conductivity up to 1000 cm-1 in the low temperature phase. This is accompanied be a non-linear transport with a smooth onset at about 10 V /cm. Our X-ray studies show no indication of superstructure reflections and clearly rule out the formation of a charge density wave ground state. The lack of a temperature dependence in the millimeter wave conductivity between 20 K and 100 K makes hopping transport unlikely.