A. V. Lukoyanov

Evolution of the electronic structure and physical properties of Fe2MeAl (Me = Ti, V, Cr) Heusler alloys

We present the results of experiments on the optical, electrical and magnetic properties and electronic structure and optical spectrum calculations of the Heusler alloys Fe2TiAl, Fe2VAl and Fe2CrAl. We find that the drastic transformation of the band spectrum, especially near the Fermi level, when replacing the Me element (Me = Ti, V, Cr), is accompanied by a significant change in the electrical and optical properties. The electrical and optical properties of Fe2TiAl are typical for metals. The abnormal behavior of the electrical resistivity and the optical properties in the infrared range for Fe2VAl and Fe2CrAl are determined by electronic states at the Fermi level. Both the optical spectroscopic measurements and the theoretical calculations demonstrate the presence of low-energy gaps in the band spectrum of the Heusler alloys. In addition, we demonstrate that the formation of Fe clusters may be responsible for the large enhancement of the total magnetic moment in Fe2CrAl.

Local correlations and hole doping in NiO: A dynamical mean-field study

Using a combination of ab initio band-structure methods and dynamical mean-field theory, we study the single-particle spectrum of the prototypical charge-transfer insulator NiO. Good agreement with photoemission and inverse-photoemission spectra is obtained for both stoichiometric and hole-doped systems. In spite of a large

Sm2Fe17 and Tm2Fe17: electronic structure, magnetic and optical properties

mathrm{Ni}phantom{rule{0.2em}{0ex}}d

Doped Mott insulator as the origin of heavy-fermion behavior in LiV2O4.

spectral weight at the top of the valence band, the doped holes are found to occupy mainly the ligand

Specific features of the behavior of the optical properties of TbNi5 − xCux intermetallic compounds

p

Optical absorption and structure of energy bands of GdNi5 − xCux intermetallic compounds

orbitals. Moreover, high hole doping leads to a significant reconstruction of the single-particle spectrum accompanied by a filling of the correlation gap.

Influence of aluminum impurity on the electronic structure and optical properties of the TbNi5 intermetallic compound

For two intermetallics, the results of experimental measurements of optical and magnetic properties together with calculations in the frame of the LSDA+U method are reported. The calculations of the electronic structure allow one to interpret the curves of optical conductivity extracted from direct experimental ellipsometry measurements of optical constants. A detailed analysis shows that, whereas experimental curves of the optical conductivity for both compounds are similar to each other, the contributions of various interband transitions are slightly different. Also band structure calculations give magnetic structure and values of magnetic moments for each ion in Sm2Fe17 and Tm2Fe17 as well as the total one in good agreement with experimental values if the orbital moment is taken into account. Obtained optical theoretical and experimental results demonstrate good agreement with each other for both intermetallics.

Orbital density functional as a means to restore the discontinuities in the total-energy derivative and the exchange?correlation potential

We investigate the electronic structure of LiV2O4, for which heavy-fermion behavior has been observed in various experiments, by the combination of the local density approximation and dynamical mean field theory. To obtain results at zero temperature, we employ the projective quantum Monte Carlo method as an impurity solver. Our results show that the strongly correlated a 1g band is a lightly doped Mott insulator which, at low temperatures, shows a sharp (heavy) quasiparticle peak just above the Fermi level, which is consistent with recent photoemission experiments by Shimoyamada et al. [Phys. Rev. Lett. 96, 026403 (2006)10.1103/PhysRevLett.96.026403].

Transition of iron ions from high-spin to low-spin state and pressure-induced insulator-metal transition in hematite Fe2O3

The optical properties of the TbNi5 − xCux intermetallic compounds have been investigated in the spectral range 0.08–5.64 eV by the ellipsometric method. It is shown that substitution of nickel for copper atoms leads to a significant change in the frequency dependence of the optical conductivity; this change is related to modification of the electronic spectrum. The formation of a new interband absorption band has been revealed, whose intensity increases with an increase in the copper content. The concentration dependences of the plasma and relaxation frequencies of conduction electrons in the compounds under study are determined. Self-consistent calculation of the electronic structure of the TbNi5 binary compound has been performed in the approximation of local electron spin density. The electron density of states for two spin projections and the optical conductivity of this compound have been calculated.

Calculation of temperature dependence of electrical resistivity in the transuranium metals and their alloys

Optical properties of intermetallic compounds GdNi5 − xCux (x = 0, 0.5, 1, 1.5, and 2) have been studied in a spectral range from 0.22 to 15 μm using the ellipsometry method. The substitution of copper for nickel has been found to lead to local changes in the interband optical conductivity spectra. A new quantum-absorption band, whose intensity increases substantially with increasing copper content, has been found at 3–4 eV. The relaxation and plasma frequencies of conduction electrons, which were calculated using data on the optical parameters, also depend on the concentration. Self-consistent calculations of the electronic structure of the intermetallic binary GdNi5 compound have been performed using the LSDA + U method. The density of electronic states for two spin projections and the frequency dependence of the interband optical conductivity of the compound have been calculated.