Electronic Structure and Ordering Degree in $Fe_3Al$ Alloy Doped with Transition Metals. Ab Initio Study

$Fe_3Al$ alloy crystallizes in $DO_3$-type structure. In the perfectly ordered alloy there are two nonequivalent sublattices (A,C) and B, which are occupied by Fe atoms, whereas all D sites are taken by metalloid. Such perfect ordering is, however, difficult to achieve experimentally, and some disorder between B-D as well as (A,C)-D sublattices typically appears in real samples. This disorder modifies strongly electronic structure and magnetic properties. The aim of this contribution is to investigate total energy dependence of atomic exchange of sites between B-D and (A,C)-D positions in $Fe_3Al$ as well as in alloys doped with transition metals using ab-initio technique. Furthermore, dependence of electronic and magnetic properties of $Fe_3Al$-based alloys on the crystallographic ordering is thoroughly investigated