Magnetic moment of iron atoms in Fe-Al body-centered cubic alloys as a function of the nearest environment

Abstract

The Fe-Al systems in the concentration range from 29 to 44 at. % Al are investigated in terms of the density functional theory. It is shown that, in the system under consideration, there can exist three magnetic states with close energies. Two of these three magnetic states have collinear magnetic moments (the ferromagnetic and antiferromagnetic states), and the third is a spin-spiral state. In collinear magnetic structures, the local magnetic moments are determined by the nearest chemical environment and, in the antiferromagnetic state, the iron atoms surrounded by a large number of aluminum atoms in their environment have a negative magnetic moment. The results obtained substantiate the applicability of modified models of the Jaccarino-Walker type for the interpretation of the experimental data obtained for Fe-Al alloys. The results of the calculations also indicate a significant role of Stoner excitations in the formation of magnetic order in these alloys.