Effect of chemical order on the magnetic and electronic properties of epitaxial off-stoichiometryFexSi1−xthin films

Abstract

Off-stoichiometry, epitaxial Fe x Si 1-x thin films (0.5<x<1.0) exhibit D0 3 or B2 chemical order, even far from stoichiometry. Theoretical calculations show the magnetic moment is strongly enhanced in the fully chemically disordered A2 phase, while both theoretical and experimental results show that the magnetization is nearly the same in the B2 and D0 3 phases, meaning partial chemical disorder does not influence the magnetism. The dependencies of the magnetic moments are directly and non-linearly linked to the number of Si atoms, primarily nearest neighbor but also to a lesser extent (up to 10%) next nearest neighbor, surrounding Fe, explaining the similarities between B2 and D0 3 and the strong enhancement for the A2 structure. The calculated electronic density of states shows many similarities in both structure and spin polarization between the D0 3 and B2 structures, while the A2 structure exhibits disorder broadening and a reduced spin polarization.2

Effect of local environment on moment formation in iron silicides

“…Particularly, the magnetic moment per iron atom in amorphous films is higher, than in epitaxial [39,40]. For example, the experiments and ab initio calculations [39] show that in amorphous films the magnetic moment per Fe atom μ Fe ≈ 0.65μ B at 50% concentration of Si, contrary to the situation in the alloys with B2 structure. Thus, the possibility of occupation of the Fe II sites by Si atoms is one of main structural features which differ disordered random solid solution from B2-like structures and is directly related to the mechanisms of magnetic moment formation.…”

“…The electron and magnetic properties of the epitaxial and amorphous films are also essentially differ from each other [39,40]. Particularly, the magnetic moment per iron atom in amorphous films is higher, than in epitaxial [39,40]. For example, the experiments and ab initio calculations [39] show that in amorphous films the magnetic moment per Fe atom μ Fe ≈ 0.65μ B at 50% concentration of Si, contrary to the situation in the alloys with B2 structure.…”

“…An increase of the Si concentration till 50%, i.e., when all Fe I atoms are replaced by Si ones (see Fig.5), the magnetic moment of the elementary cell vanishes. The partially ordered structure of the B2 type are observed in most of epitaxial Fe -Si films [17,39]. In amorphous films situation is different, there a chemically disordered random solid solution is formed: the Si atoms can occupy any of iron positions, Fe I or Fe II .…”

Approach to form planar structures based on epitaxial Fe1−xSix films grown on Si(111)

“…Finally, the D03 structure is chemically ordered with Fe on the cube corners and Fe and Si alternating in the body centers [16]. In particular, increasing silicon content leads to a decrease in the carrier concentration, which is important in the context of the resistivity mismatch in spin transistors devices without an oxide tunnel barrier [17]. Moreover, this can also bring about a larger magneto-optical Kerr effect than in case of bcc-Fe, that is crucial for magnetophotonic applications [18].…”

Effect of the Local Environment on the Magnetic Properties of Mn3Si: Hybrid Ab Initio and Model Study

“…One of the most exciting compounds from the transition metal silicides family is the Heusler compounds of T 3 Si with the DO 3 ‐type cubic crystal structure. The reason why the compound T 3 Si has long attracted attention is the presence of metal properties along with high‐spin polarization . One more motivation for studying the T 3 Si system (T‐transition metal) is the possibility to tune its magnetic properties.…”