Enhanced thermoelectric power and cooling ability near the Anderson transition

The thermoelectric power (S) and the thermoelectric figure of merit (Z, a measure of the ability of a material to be a good thermoelectric cooler) at and near the disorder-driven (Anderson) metal-isolator transition at the metallic side is calculated without applying the standard Sommerfeld expansion. The expansion was shown earlier to yield erroneous results. The thermoelectric power is not divergent at the transition but its large magnitude is sufficient for the figure of merit to be considerably greater at the transition than that estimated in an earlier paper under erroneous assumption of its divergence. A correspondence of the obtained expressions for S and Z to those usually applied to study semimetals and semiconductors is manifested.