First-principles calculations of electronic structures and ferromagnetism of Fe3Si(001)//MgO(001) films

The first-principles calculations based on density functional theory (DFT) were carried out in investigating electronic structures and ferromagnetism of Fe3Si films epitaxial on MgO(001). Firstly, the various geometric structures of Fe3Si(001)//MgO(001) constructed near lattice constant c = 3.995 angstrom were optimized to gain the most steady equilibrium state at c = 3.980 angstrom. Then, the calculated cohesive energy and negative heat of formation indicate that Fe3Si(001)//MgO(001) formed in this manner obtain high structural stability. The calculated results of spin-polarized energy band structures and density of states show that Fe3Si(001)//MgO(001) exhibit the metallic feature whose bonding orbitals are constituted by covalent bond and metallic bond. Two peaks located in both the sides of the Fermi level and the total density of states (TDOS) in this energy range are all due to the Fe 3d states, which implies that the pseudo energy gap exists in the Fermi level and covalent electron orbit hybridization takes place. Ferromagnetism of Fe3Si(001)//MgO(001) are determined by the 3d states of Fe atoms. There are two occupied sites for Fe atoms with different local magnetic moments, which is 1.34 mu(B)/atom for Fe[A, C] atoms and a value of 2.68 mu(B) /atom for Fe[B] atoms, likewise indicating Fe3Si films epitaxial on MgO(001) are ferromagnetic.