Growth of Mn$_{2}$TiSn alloy and its magnetic and structural characterizations

A ternary inter-metallic alloy Mn$_{2}$TiSn is one of the candidates predicted to be a Heusler compound with high spin polarization and Curie temperature well above room temperature, which is suitable for spintronic applications. Mn$_{2}$TiSn powder samples were prepared by arc melting and annealing under controlled environment to study magnetic and structural properties. Temperature and field dependent magnetization measurements show the sample is ferromagnetically ordered with a Curie temperature above 400 K. The low temperature magnetization at 10 K is about 2.5 emu/g under 100 Oe. The coercivity increases as temperature decreases from 1 kOe at room temperature to 2.4 kOe at 10 K. Theoretical calculation from the high field data shows the anisotropy energy is 4.0 $\times$ 10$^{5}$ ergs/cm$^{3}$ at 300 K but it becomes slightly more than doubled at 10 K. TEM and XRD characterizations reveal that the compound crystallizes in the hexagonal structure (D0$_{19}$, P6$_{3}$/mmc) rather than the theoretically proposed L2$_{1}$ cubic structure, which is supported by the first-principle structure calculations where the total energy per unit cell volume is preferred for the hexagonal structure.