Saturation magnetization and crystalline anisotropy calculations for MnAl permanent magnet

Theoretical saturation magnetization and magnetocrystalline anisotropy energy (MAE) of τ-phase (face-centered tetragonal) Mn₅₀Al₅₀ alloy were obtained by first principles calculations, and the alloy was fabricated to compare the experimental values with the theoretical predictions. The calculated magnetic moment and MAE for τ-phase Mn₅₀Al₅₀ were 2.37 μ_B/f.u. and 0.259 meV/f.u. (1.525×10⁶ J/m³), respectively, which result in the maximum energy product (BH)_max of 12.64 MG Oe and the magnetocrystalline anisotropy field of 38 kOe. The saturation magnetization for τ-phase Mn₅₄Al₄₆ alloy was measured to be 98.3 emu/g, which gives 4.7 MG Oe of (BH)_max. The magnetization is about 70% of the theoretical value of 144 emu/g.