Possible Enhancement of Thermoelectric Properties by Use of a Magnetic Semiconductor: Carrier-Doped Chalcopyrite Cu1−xFe1+xS2

We focus on the chalcopyrite CuFeS2 to utilize the interaction between carriers and magnetic moments of Fe as a possible source to achieve high power factor. Polycrystalline samples of Cu1−xFe1+xS2 were synthesized, and their thermoelectric properties are reported. Electrical resistivity decreased by two orders of magnitude with increasing x, while the Seebeck coefficient showed large values of −200 μV/K at room temperature. Thermal conductivity also decreased with the increase of x. As a result, the power factor and the figure of merit, zT, of the carrier-doped samples are about 10 times larger than those of CuFeS2. These observations suggest that magnetic semiconductors can make good thermoelectric materials.