Extreme thermopower anisotropy and interchain transport in the quasi-one-dimensional metal Li0.9Mo6O17.

Abstract

Thermopower and electrical resistivity measurements transverse to the conducting chains of the quasi-one-dimensional metal Li0.9Mo6O17 are reported in the temperature range 5≤T≤500 K. For T≥400 K the interchain transport is determined by thermal excitation of charge carriers from a valence band ∼0.14 eV below the Fermi level, giving rise to a large, p-type thermopower that coincides with a small, n-type thermopower along the chains. This dichotomy-semiconductorlike in one direction and metallic in a mutually perpendicular direction-gives rise to substantial transverse thermoelectric effects and a transverse thermoelectric figure of merit among the largest known for a single compound.