Work

Transition metal alloys are widely used in modern science and technology. To understand the microscopic nature of physical characteristics of these alloys is important for the development and prediction of changes in properties of materials used in spintronics, aerospace, and nuclear technology etc. In our paper series, we represent such new results. The distinctive features of the electronic and magnetic structures of Co2FeSi and Co2FeGa Heusler alloys, as well as CeFe2 and LaMnO3 are obtained theoretically from first principles using the fully relativistic Dirac LMTO band structure method. The calculated densities of valence states, orbital and spin magnetic moments as well as the x-ray absorption spectra (XAS), x-ray magnetic circular dichroism (XMCD), and resonant magnetic x-ray scattering spectra (for LaMnO3 only) of the alloys are analyzed and discussed. MeCrS2 compounds with triangular Cr layers show a large variety of magnetic ground states originating from a competition between antiferromagnetic direct nearest-neighbor d-d exchange between Cr atoms and ferromagnetic superexchange via S p states. The expression for the mass operator of the electron-electron interaction in which the contributions of static and dynamic fluctuations of the charge and spin densities are separated clearly has been obtained within the cluster expansion for Green functions and thermodynamic potential of disordered crystal system with strong electron correlations. The influence of the atomic and magnetic order and temperature on the electronic structure of the disordered b.c.c.-Fe–Co alloy and static conductivity is investigated. The features of magnetic and transport properties of these alloys due to the restructuring of the energy spectrum of electrons are revealed. It is shown a non-monotonic concentration dependence of the electrical resistance in b.c.c.-Fe–Co alloy is governed by strong electron correlations and the resulting magnetic order. The self-consistent harmonic approximation method based on the double-time Green functions is adapted to the metals with hexagonal closed-packed structure. The expression for the dynamic matrix of h.c.p.-crystals in which contributions from central and non-central interatomic interaction forces are separated clearly is obtained taking into account the effects of anharmonicity and electron-phonon interaction. The influence caused by non-ideal structure anisotropy and thermal crystalline lattice vibration anharmonicity as well as non-central interatomic force contribution in the phonon spectrum and self-diffusion properties along the c and a axes are studied for h.c.p.-titanium. It is shown this anharmonicity leads to further decrease in potential barrier strength for substitution atomic diffusion activation in titanium based alloys being the reason for their relatively high creep. The ab initio electronic structure calculations carried out in our paper series allow us to analyze the intricacies of physical mechanisms responsible for the formation of electric, magnetic, and mechanical properties of the investigated alloys more versatily and reliably for their future possible use in modern technology.