Electronic structure and magnetic properties of ordered Fe1−xNix and Fe1−x Cox alloys

The electronic structure and magnetism of ordered Fe1−xNix and Fe1−xCox alloys were calculated by using the first-principles linearized augmented plane-wave (LAPW) method with the local spin density approximation (LSDA). The results indicate that the magnetic properties of both Fe1−xNix and Fe1−xCox are sensitive to their compositions as well as their structures. The FCC structured Fe1−xNix alloys with x=0, 0.5, 0.75, 1 are ferromagnetic ordered, while Fe1−xNix at x=0.25 is ferrimagnetic ordered. For both BCC and FCC structured Fe1−xCox alloys, however, they present ferromagnetic ordering in all compositions. With the increase of Fe compositions for Fe1−xCox, the average magnetic moments increase abruptly and then decrease smoothly, which is in good agreement with experimental results.