Structural and magnetic properties of Mn_2+δTiSn

The structural and magnetic properties of Mn_2+δTiSn prepared by arc melting and annealing have been investigated. Structural studies show that the compound crystallizes in the hexagonal Ni₃Sn-type structure with a = 5.70 Å and c = 4.55 Å. The phase stability of Mn₂TiSn in the hexagonal structure is supported by the first-principle electronic structure calculations where the total energy per unit-cell volume in the hexagonal structure is smaller than that in the cubic structure. Field and temperature dependence of magnetization show that the sample is magnetically ordered with a Curie temperature around 400 K. The anisotropy energy calculated from the high-field data is 4.0 × 10⁵ ergs/cm³ at 300 K but increases by a factor of two (8.6 × 10⁵ ergs/cm³) as temperature decreases to 10 K. The observed magnetic properties are explained as the consequences of competing ferromagnetic and antiferromagnetic interactions between different magnetic sublattices.