Thermoelectric Power of Tetrathiofulvalinium Tetracyanoquinodimethane

Abstract

Measurements of the thermopower of the organic conductor tetrathiofulvalinium tetracyanoquinodimethane have been made in the region 10-300\ifmmode^\circ\else\textdegree\fi{}K. At high temperatures ($T>140\ifmmode^\circ\else\textdegree\fi{}$K) the samples are metallic showing increased electron correlations as the temperature is lowered to about 56\ifmmode^\circ\else\textdegree\fi{}K. At this point the thermopower is zero and a discontinuity marks the transition to the insulating state.