Thermal Transport Properties of Bechgaard Salts (TMTSF)2PF6 and (TMTSF)2ClO4: Implication of Spin-Charge Separation

We report thermal transport measurements performed on the quasi-one-dimensional Bechgaard salts (TMTSF)2ClO4 and (TMTSF)2PF6 along the a-direction. For both salts, magnon-drag effects are found to contribute considerably to thermopower above 80 K. These results imply spin-charge separation in the metallic state for both salts. Moreover, a linear temperature-dependent thermal conductivity is found to be unaffected by anion disorder below an anion ordering transition temperature TAO~25 K in (TMTSF)2ClO4.