Electronic Structure and Magnetocrystalline Anisotropy Energy of MnAl

The spin-polarized band calculations including spin-orbit interaction for τ -phase (L1 0 ) MnAl have been performed with LMTO-ASA method in the frame of LSD. It has been predicted that the MnAl has a magnetic moment of 2.4 µ B with a help of the tetragonal distortion from cubic B2 to L1 0 structure. The magnetocrystalline anisotropy energy (MAE) is obtained as (0.26 ± 0.01) meV/f.u. This leads to 1.5 ×10 6 J/m 3 for magnetic anisotropy constant which is comparable to the measured value ∼10 6 J/m 3 . The dependence of the MAE on axial ratio c / a also reflects the influence of the tetragonal distortion, that is, the MAE shows drastic change from negative to positive at the vicinity of c / a =0.7071 which corresponds to cubic B2 lattice. For larger value of c / a , MAE decreases with increasing c / a and goes into negative again for c / a >1.2.