High Thermoelectric Power Factor in a Carrier-Doped Magnetic Semiconductor CuFeS₂

The chalcopyrite CuFeS 2 is a natural magnetic semiconductor, where Fe spins order antiferromagnetically at T N = 853 K. We investigate the thermoelectric properties of the carrier-doped chalcopyrite alloys, Cu 1- x Fe 1+ x S 2 with x = 0.03 and 0.05, and Zn 0.03 Cu 0.97 FeS 2 . All systems showed characteristic behavior of n -type degenerate semiconductors. The large Seebeck coefficient with a high carrier-density indicates enhanced carrier mass of m * = 3–6 m 0 , where m 0 is the electron mass. Consequently, the thermoelectric power factor exceeds 1 × 10 -3 W K -2 m -1 at 400 K. We propose that utilizing magnetic semiconductor can be a new effective strategy to obtain enhanced values of the power factor.