M. Dressel et al., FIELD AND FREQUENCY-DEPENDENT TRANSPORT IN THE 2-DIMENSIONAL ORGANIC CONDUCTOR ALPHA-(BEDT-TTF)2I3, Journal de physique. I, 4(4), 1994, pp. 579-594
The title compound undergoes a metal-insulator phase transition of unk
nown origin at T(MI) = 135 K. We studied the electrodynamic response o
f alpha-(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 w
ith a smooth onset at about 10 V/cm. Our X-ray studies show no indicat
ion of superstructure reflections and clearly rule out the formation o
f a charge density wave ground state. The lack of a temperature depend
ence in the millimeter wave conductivity between 20 K and 100 K makes
hopping transport unlikely.