Analysis of optical and magnetooptical spectra of Fe5Si3 and Fe3Si magnetic silicides using spectral magnetoellipsometry

Lyashchenko, S. A.; Попов, Захар И.; Варнаков, С. Н.; Попов, Э. Г.; Molokeev, Maxim S.; Yakovlev, I. A.; Кузубов, А. А.; Овчинников, С. Г.; Шамирзаев, Т. С.; Латышев, А. В.; Саранин, А. А.

doi:10.1134/s1063776115050155

Cited by 12 publications

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“…To this day, several Fe-silicide structures have been reported. At the Fe-rich side of the binary phase diagram, metallic as well as ferromagnetic F e 5 Si 3 and F e 3 Si (DO 3 structure) [7,8]have already been established as key materials for spintronics [8,9]. The Si -rich side of the phase diagram contains several variants of a disilicide stoichiometric compound, such as the high-temperature tetragonal metallic α − F eSi 2 phase [11], with applications as an electrode or an interconnect material [12,13], and the orthorhombic semiconducting β − F eSi 2 phase [14], which due to its direct band gap is an interesting candidate for thermoelectric, photovoltaic and optoelectronic devices [15].…”

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confidence: 99%

Self-consistent mapping: Effect of local environment on formation of magnetic moment in α−FeSi2

et al. 2017

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The Hohenberg-Kohn theorem establishes a basis for mapping of the exact energy functional to a model one provided that their charge densities coincide. We suggest here to use a mapping in a similar spirit: the parameters of the formulated multiorbital model should be determined from the requirement that the self-consistent charge and spin densities found from the ab initio and model calculations have to be as close to each other as possible. The analysis of the model allows for detailed understanding of the role played by different parameters of the model in the physics of interest. After finding the areas of interest in the phase diagram of the model we return to the ab initio calculations and check if the effects discovered are confirmed or not. Because of the last controlling step we call this approach as hybrid self-consistent mapping approach (HSCMA). As an example of the approach we present the study of the effect of silicon atoms substitution by the iron atoms and vice versa on the magnetic properties in the iron silicide α − F eSi2. The DFT+GGA calculations are mapped to the model with intraatomic Coulomb and exchange interactions, hoppings to nearest and next nearest atoms and exchange of the delocalized electrons between iron atoms; the magnetic moments on atoms and charge densities of the material are found self-consistently within the Hartree-Fock approximation.We find that while the stoichiometric α − F eSi2 is nonmagnetic, the substitutions generate different magnetic structures. For example, the substitution of three Si atoms by the F e atoms results in the ferrimagnetic structure whereas the substitution of four Si atoms by F e atoms gives rise to either the nonmagnetic or the ferromagnetic state depending on the type of local enviroment of the substitutional F e atoms. Besides, contrary to the commonly accepted statement that the destruction of the magnetic moment is controlled only by the number of F e − Si nearest neighbors, we find that actually it is controlled by the F e − F e next-nearest-neighbors' hopping parameter. This finding led us to the counterintuitive conclusion: an increase of Si concentration in F e1−xSi2+x ordered alloys may lead to a ferromagnetism. This conclusion is confirmed by the calculation within GGA-to-DFT.

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