Electronic structure and magnetism of Fe3Al1−xSix alloys

Total energy and electronic structure calculations for Fe3Al1−xSix alloys with DO3-type structure have been performed to understand structural and magnetic properties using plane-wave pseudopotential method. With the increase of Si content, the equilibrium lattice constants reduce linearly and the saturation magnetic moments per unit cell of Fe3Al1−xSix alloys decrease, which are in good agreement with the experimental results. To illustrate the origin of magnetism of Fe3Al1−xSix alloys, spin-polarized density of states and local magnetic moments are investigated. The results show that the difference in local moments of Fe(A,C) and Fe(B) is due to different local environment in DO3-type structure and the relative affinity of Si and Al for Fe. In addition, to analyze the effect of Si on the magnetism of Fe3Al, the Mulliken charge and bond population are used to study the charge transfer and the bonding types, respectively. The calculated results give a reasonable explanation of recent experimental findings.