First-Principles study of thermoelectric properties of Half-Metallic Non-Magnetic Half-Heusler alloy Mn₂Ge

Research about Heusler alloys have been massively conducted through experimental and theoretical studies due to their fascinating properties. Most of Heusler alloy compounds exhibit half-metallic behavior, in which one of the spin channels of such a material behaves as a metal and the other behaves as an insulator because there is an open energy gap at the Fermi level. On the other hand, the thermoelectric properties of the materials usually work well in the insulator or semiconductor phase rather than in the metal phase. Motivated by such interesting phenomena, we conduct first-principles study to explore the thermoelectric properties of Mn2Ge, one of Heusler compounds that exhibits half-metallic behavior. Our calculation results show that Mn2Ge of the spin-down channel has a high Seebeck coefficient and ZT value (electron part) at room temperature around 892 MV/K and 0.97, respectively. The positive sign of the Seebeck coefficient on spin-up and spin down indicate that the majority charge carrier in Mn2Ge are positive charges (holes).