Large magnetic anisotropy in hexagonal Fe₂MnSn alloy

We performed combined theoretical and experimental studies of electronic, magnetic, and structural properties of Fe₂MnSn Heusler alloy. The density functional theory (DFT) calculations of bulk and thin-film Fe₂MnSn Heusler alloys predict that this compound crystallizes in energetically close hexagonal D0₁₉ and cubic L2₁ phases due to their very similar equilibrium energies, which agrees well with the experimental results. Both the cubic and hexagonal phases are ferromagnetic with high T_c of 325 K and 475 K, respectively. The high-field magnetizations measured at 100 K are 3.3 µ_B/f.u. and 4.3 µ_B/f.u) for the cubic and hexagonal phases, respectively. These values are smaller than the predicted values (6.0 µ_B/f.u. for the cubic and 6.5 for the hexagonal phases) by the DFT calculations. The hexagonal phase shows high value of magnetic anisotropy of 5.1 Merg/cm³ at 100 K. The cubic phase has an energy gap in the minority-spin conduction band that vanishes in the hexagonal phase.