Electronic structure and site preference of transition-metal impurities in Fe3Si

In the intermetallic compound Fe 3 Si there are two non-equivalent Fe sites, one (C) with cubic symmetry and another (T) with tetrahedral symmetry. Impurities from the first transition row show a marked tendency at thermal equilibrium to occupy one or other of the two types of sites preferentially; impurities from the left of Fe such as Mn preferring the C site and impurities from the right of Fe such as Co preferring the T site. In this paper the authors calculate (i) the band structure Fe 3 Si, (ii) the local densities of states of the pure system for various sites and spin orientations from Haydock's method and (iii) similar local densities of states of the systems with various impurities in both possible positions. One-electron total energies are compared and they find that the calculations give the correct site preferences in terms of them. A simple physical interpretation of the results is proposed.