MAXIMUM-ENTROPY RECONSTRUCTION OF THE INTERNAL MAGNETIZATION DENSITY DISTRIBUTIONS IN FE-3(ALXSI1-X) ALLOYS

Magnetization distributions in Fe3Al, Sendust, Fe3Si and Fe4Si have been reanalysed by applying the model-free maximum-entropy method. The results show that in the first three alloys the magnetic moments of iron at the B sites decrease while their e(g)-type asphericities increase with increasing silicon content. The asphericities at (A, C) sites are not very different from those at B sites. Compared with the situation in BCC iron, the formation of DO3 ordering with the presence of silicon increases the number of e(g) states at the Fermi level, while the opposite is true for aluminium atoms. Iron substituting for aluminium or silicon exhibits a substantially different degree of asphericity than exhibited at B sites. In the case of substitution for silicon a decrease in the magnetic moments at D sites with respect to the B sites is seen. The spatial extent of the magnetization distribution at iron sites is generally more extended than observed in pure iron. From the purely maximum-entropy point of view, negative magnetization is not needed for the magnetic structure factor reconstruction. However, at least in the case of Sendust alloy, it is shown that such magnetization is necessary in order to obtain a sensible spatial distribution of the magnetization at the D site. It is shown that, once negative magnetization is allowed, its distribution throughout the unit cell has a localized character.