Electronic Structure and Magnetocrystalline Anisotropy Energy of MnAl

Abstract

The spin-polarized band calculations including spin-orbit interactionfor τ -phase (L1₀) MnAl have been performed with LMTO-ASAmethod in the frame of LSD. It has been predicted that the MnAl has amagnetic moment of 2.4, μ _B with a help of the tetragonaldistortion from cubic B2 to L1₀ structure. The magnetocrystallineanisotropy energy (MAE) is obtained as (0.26 ± 0.01) meV/f.u. Thisleads to 1.5 × 10⁶, J/m³ for magnetic anisotropy constant which is comparable to the measured value -- 10⁶, J/m³. 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.