Magnetic and thermoelectric properties of Co2MnT (T = Ga, Si) Heusler compounds

Highlights: • The Co2MnGa and Co2MnSi Heusler compounds were confirmed to be ferromagnetic. • The Co2MnSi Heusler compound exhibited a high Curie temperature. • The Co2MnGa and Co2MnSi Heusler compounds were n-type thermoelectric materials. • The Co2MnSi Heusler compound showed a power factor of 1800 μW/mK2 at 600 K. Magnetic measurements confirmed that the Co₂MnSi Heusler compound is a superior ferromagnetic material to the Co₂MnGa Heusler compound. The Co₂MnGa Heusler compound showed a saturation magnetization of 81.3 emu/g and a Curie temperature of 700 K, while the Co₂MnSi Heusler compound exhibited both a high saturation magnetization of 130 emu/g and a high Curie temperature of 1015 K. Thermoelectric measurements revealed that the Co₂MnSi Heusler compound is also a superior thermoelectric material to the Co₂MnGa Heusler compound. The Co₂MnGa Heusler compound showed a large Seebeck coefficient of −35.2 μV/K and a low electrical resistivity value of 1.30 μΩm at room temperature, while the Co₂MnSi Heusler compound showed values of −14.3 μV/K and 0.198 μΩm, respectively. A power factor of 1800 μW/mK² at 600 K was obtained in the Co₂MnSi Heusler compound, which is comparable to or higher than that of the well-known Fe₂VAl Heusler compound.