Band Theory of Super-Lattice Fe₃Al

Abstract

The energy bands of an ordered alloy Fe 3 Al both in paramagnetic and ferromagnetic state are calculated by the symmetrized augmented plane wave (SAPW) method. There are two types of iron atoms (Fe(I) and Fe(II)) in ferromagnetic state with a different value of the magnetic moment. The density-of-states of Fe(I) which has eight iron atoms as its nearest neighbors is different from that of Fe(II) which is surrounded by four iron atoms and four aluminum atoms. The former density is quite similar to that of iron metal, but the latter is considerably different. The d -bands of majority spin electrons mostly lie below the Fermi level, whereas those of minority spin electrons are extended across the Fermi level. The values of magnetic moments calculated for Fe(I) and Fe(II) are in good agreement with experimental values. The difference between magnetic moments on the atom Fe(II) and on Fe atom in iron metal seems to be attributed to the change of the density-of-states near the top of the d -bands. It is evident that the electronic structures of Fe(II) atoms have been considerably affected by the neighboring aluminum atoms.