arXiv subjects

A. L. Ivanovskii

Publications and source records attributed to A. L. Ivanovskii.

At least 55 records · Page 3Linked to original sources

arXiv2009

Structural, electronic and magnetic properties of ether carbides (Fe3W3C, Fe6W6C, Co3W3C and Co6W6C) from first principles calculations

First-principles FLAPW-GGA calculations have been performed with the purpose to determine the peculiarities of the structural, electronic, magnetic properties and stability for a family of related ether carbides M3W3C and M6W6C (where M= Fe and Co). The geometries of all phases were optimized and their structural parameters, theoretical density, cohesive and formation energies, total and partial densities of states, atomic magnetic moments have been obtained and analyzed in comparison with available theoretical and experimental data.

cond-mat.mtrl-sci↗

arXiv2009

Band structure of new layered 17 K superconductor Sr4Sc2Fe2P2O6 in comparison with hypothetical Sr4Sc2Fe2As2O6

The results of the ab initio FLAPW-GGA calculations of the band structure of the newly synthesized tetragonal (space group P4/nmm) layered iron phosphide-oxide: 17K superconductor Sr4Sc2Fe2P2O6 are presented. For Sr4Sc2Fe2P2O6 the optimized structural data, the energy bands, total and partial densities of states, Fermi surface topology, low-temperature electron specific heat and molar Pauli paramagnetic susceptibility have been determined and discussed in comparison with hypothetical isostructural iron arsenide-oxide phase Sr4Sc2Fe2As2O6 and related layered FeAs and FeP superconductors.

cond-mat.supr-con↗

arXiv2008

Band structure of (Sr3Sc2O5)Fe2As2 as a possible parent phase for new FeAs superconductors

By means of first-principles FLAPW-GGA calculations, we have investigated the electronic properties of the newly synthesized layered phase - (Sr3Sc2O5)Fe2As2. The electronic bands, density of states and Fermi surface have been evaluated. The resembling of our data for (Sr3Sc2O5)Fe2As2 with band structure pictures of known FeAs superconducting materials may be considered as the theoretical background specifying the possibility for (Sr3Sc2O5)Fe2As2 to become a parent phase for new FeAs superconductors.

cond-mat.supr-con↗

arXiv2008

Electronic and elastic properties of new nitrogen-containing perovskite-like superconductor ZnNNi3

Full-potential linearized augmented plane wave (FP-LAPW) method with the generalized gradient approximation (GGA) for the exchange-correlation potential has been applied for the study of structural, elastic and electronic properties of the newly synthesized nitrogen-containing perovskite-like superconductor ZnNNi3. The optimized lattice parameter, independent elastic constants (C11, C12 and C44), bulk modulus B, compressibility betta, and shear modulus G are evaluated. The band structure, total and site- projected l- decomposed DOSs, the shape of the Fermi surface, the Sommerfeld coefficient and the molar Pauli paramagnetic susceptibility for this novel anti-perovskite are obtained and analyzed in comparison with related anti-perovskites ZnCNi3 and MgCNi3

cond-mat.supr-con↗

arXiv2008

First-principles study of electronic band structure and elastic properties of superconducting nanolaminate Ti2InC

The full-potential linearized augmented plane wave method with the generalized gradient approximation for the exchange-correlation potential (FLAPW-GGA) is used to predict the electronic and elastic properties of the newly discovered superconducting nanolaminate Ti2InC. The band structure, density of states and Fermi surface features are discussed. The optimized lattice parameters, independent elastic constants, bulk and shear moduli, compressibility are evaluated and discussed. The elastic parameters of the polycrystalline Ti2InC ceramics are estimated numerically for the first time.

cond-mat.mtrl-sci↗

arXiv2008

Band structure of tetragonal and orthorhombic fluorine-arsenide SrFeAsF as a parent phases for a new group of oxygen-free FeAs superconductors

The full-potential linearized augmented plane wave method with the generalized gradient approximation for the exchange and correlation potential (LAPW-GGA) is used to understand the electronic band structure of fluorine-arsenide SrFeAsF as a possible parent material for a new group of oxygen-free FeAs superconductors. The electronic bands, density of states, Fermi surface and atomic charges have been evaluated and discussed for high-temperature tetragonal and low-temperature orthorhombic SrFeAsF phases.

cond-mat.supr-con↗

arXiv2008

Band structure of SrFeAsF and CaFeAsF as parent phases for a new group of oxygen-free FeAs superconductors

By means of first-principle FLAPW-GGA calculations, we have investigated the electronic properties of the newly discovered layered quaternary systems SrFeAsF and CaFeAsF as parent phases for a new group of oxygen-free FeAs superconductors. The electronic bands, density of states, Fermi surfaces, atomic charges, together with Sommerfeld coefficients and molar Pauli paramagnetic susceptibility have been evaluated and discussed in comparison with oxyarsenide LaFeAsO - a parent phase for a new class of high-temperature (Tc about 26-56K) oxygen-containing FeAs superconductors. Similarity of our data for SrFeAsF and CaFeAsF with the band structure of oxygen-containing FeAs superconducting materials may be considered as theoretical background specifying the possibility of superconductivity in these oxygen-free systems.

cond-mat.supr-con↗

arXiv2008

Electronic band structures and intra-atomic interactions in layered quaternary oxyarsenides LaZnAsO and YZnAsO

First-principle FLAPW-GGA band structure calculations are employed to obtain the structural, electronic properties and chemical bonding picture for two related layered phases, namely, quaternary oxyarsenides LaZnAsO and YZnAsO. These compounds are found to be direct-transition type semiconductors with the GGA gaps of about 0.65-1.30 eV. The peculiarities of chemical bonding in these phases are investigated and discussed in comparison with quaternary oxyarsenide LaFeAsO - a basic phase for the newly discovered 26-52K superconductors.

cond-mat.mtrl-sci↗

arXiv2008

Elastic properties and chemical bonding in ternary arsenide SrFe2As2 and quaternary oxyarsenide LaFeAsO - basic phases for new 38-55K superconductors

We report the first-principle FLAPW-GGA calculations of the elastic properties of two related layered phases, namely, the ternary arsenide SrFe2As2 and the quaternary oxyarsenide LaFeAsO - basic phases for the newly discovered "122" and "1111" 38-55K superconductors. The independent elastic constants (Cij), bulk moduli, compressibility, and shear moduli are evaluated and discussed. The numerical estimates of the elastic parameters of the polycrystalline SrFe2As2 and LaFeAsO ceramics are performed for the first time. Additionally, the peculiarities of chemical bonding in these phases are discussed.

cond-mat.supr-con↗

arXiv2008

Elastic properties of ternary arsenide SrFe2As2 and quaternary oxyarsenide LaOFeAs as basic phases for new 38-55K superconductors from first principles

Here we report the first-principle FLAPW-GGA calculations of the elastic properties of two related phases, namely, the ternary arsenide SrFe2As2 and the quaternary oxyarsenide LaOFeAs as the basic phases for the newly discovered "1111" and "122" 38-52K superconductors. The independent elastic constants (Cij), bulk moduli, compressibility, and shear moduli are evaluated and discussed. Additionally, numerical estimates of the elastic parameters of the polycrystalline LaOFeAs and SrFe2As2 ceramics are performed for the first time.

cond-mat.supr-con↗

arXiv2008

Electronic structure of oxygen-free 38K superconductor Ba1-xKxFe2As2 in comparison with BaFe2As2 from first principles

Based on first-principles FLAPW-GGA calculation, we have investigated electronic structure of newly discovered oxygen-free 38K superconductor Ba1-xKxFe2As2 in comparison with parent phase - tetragonal ternary iron arsenide BaFe2As2. The density of states, magnetic properties, near-Fermi bands compositions, together with Sommerfeld coefficients and molar Pauli paramagnetic susceptibility are evaluated. The results allow us to classify these systems as quasi-two-dimensional ionic metals, where the conduction is strongly anisotropic, only happening on the (Fe-As) layers. According to our calculations, at the hole doping of BaFe2As2 the density of states at the Fermi level grows, and this can be a possible factor of occurrence of superconductivity for Ba1-xKxFe2As2. On the other hand, Ba1-xKxFe2As2 lays at the border of magnetic instability and the pairing interactions might involve magnetic or orbital fluctuations.

cond-mat.supr-con↗

arXiv2008

Electronic structure of new quaternary superconductors LaONiBi and LaOCuBi from first principles

Based on first-principles FLAPW-GGA calculations, we have investigated the electronic structure of newly synthesized novel superconductors LaONiBi and LaOCuBi, the first bismuth-containing compounds from the family of quaternary oxypnictides which attract now a great deal of interest in search for novel 26-55K superconductors. The band structure, density of states and Fermi surfaces are discussed. Our results indicate that the bonding inside of the (La-O) and (Ni(Cu)-Bi) layers is covalent whereas the bonding between the (La-O) and (Ni(Cu)- Bi) blocks is mostly ionic. For both oxybismuthides, the DOSs at the Fermi level are formed mainly by the states of the (Ni(Cu)-Bi) layers, the corresponding Fermi surfaces have a twodimensional character and the conduction should be strongly anisotropic andhappen only on the (Ni(Cu)-Bi) layers. As a whole, the new oxybismuthides may be described as low-TC superconducting non-magnetic ionic metals.

cond-mat.supr-con↗

arXiv2008

Electronic structure and magnetism in BeO nanotubes induced by boron, carbon and nitrogen impurities

We have performed ab initio calculations to systematically investigate electronic properties and magnetism of insulating non-magnetic beryllium monoxide nanotubes induced by non-magnetic sp impurities: boron, carbon and nitrogen. We found that in the presence of these sp impurities, which replace oxygen atoms, the non-magnetic BeO NTs transform into magnetic semiconductors, which acquire magnetization caused by spin splitting of (B,C,N) 2p states located in the forbidden gap of a BeO tube. The magnetic moments of the impurities vary from 0.65 to 1.60. On the contrary, when (B,C,N) dopants substitute for Be atoms or in the presence of an oxygen vacancy, the nonmagnetic state of the BeO tubes is retained.

cond-mat.mtrl-sci↗

arXiv2008

New enlargement of the novel class of superconductors

Here we report on synthesis and characterization of a new member LaO1-deltaNiBi in the family of novel superconductors. Though the onset superconducting temperature ~4 K is smaller compared to 55 K that has been achieved already in SmO1-deltaFeAs the similarities in crystalline structure, elec-tronic properties and low-temperature electron transport features give evidence to the common mechanism that seems to underlie the superconducting state in lanthanum nickel oxybismuthides and oxyarsenides.

cond-mat.supr-con↗

arXiv2008

Structural, magnetic and electronic properties of quaternary oxybismuthides LaOMBi (where M = Sc, Ti ... Ni, Cu) - possible parent phases for new superconducting materials

The extensive ab initio total energy calculations using the VASP-PAW method with the generalized gradient approximation (GGA) for the exchange-correlation potential are applied to systematic investigation of structural, electronic and magnetic properties in quaternary oxybismuthides LaOMBi (where M = Sc, Ti...Ni, Cu). The energy spectrum features similar to lanthanum-iron oxyarsenide LaOFeAs and non-magnetic ground state are indicative of superconductivity possible in lanthanum-nickel oxybismuthide LaONiBi.

cond-mat.supr-con↗

arXiv2008

Atomic models of non-stoichiometric layered diborides M$_{1-x}$B$_2$ (M = Mg, Al, Zr and Nb) from first principles

Two atomic models of non-stoichiometric metal diborides M$_{1-x}$B$_2$ are now assumed: (i) the presence of cation vacancies and (ii) the presence of 'super-stoichiometric' boron which is placed in cation vacancy site. We have performed first principle total energy calculations using the VASP-PAW method with the generalized gradient approximation (GGA) for the exchange-correlation potential in a perspective to reveal the trends of M$_{1-x}$B$_2$ possible stable atomic configurations depending on the type of M cations (M = Mg, Al, Zr or Nb) and the type of the defects (metal vacancies versus metal vacancies occupied by 'super-stoichiometric' boron in forms of single atoms, dimers B$_2$ or trimers B$_3$). Besides we have estimated the stability of these non-stoichiometric states (on the example of magnesium-boron system) as depending on the possible synthetic routes, namely via solid state reaction method, as well as in reactions between solid boron and Mg vapor; and between these reagents in gaseous phase. We demonstrate that the non-stoichiometric states such as B$_2$ and B$_3$ placed in metal sites may be stabilized, while the occupation of vacancy sites by single boron atoms is the most unfavorable.

cond-mat.mtrl-sci↗

arXiv2008

Elastic properties of mono- and polycrystalline hexagonal AlB2-like diborides of s, p and d metals from first-principles calculations

We have performed accurate ab initio total energy calculations using the full-potential linearized augmented plane wave (FP-LAPW) method with the generalized gradient approximation (GGA) for the exchange-correlation potential to systematically investigate elastic properties of 18 stable, meta-stable and hypothetical hexagonal (AlB2-like) metal diborides MB2, where M = Na, Be, Mg, Ca, Al, Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ag and Au. For monocrystalline MB2 the optimized lattice parameters, independent elastic constants (Cij), bulk modules (B), shear modules (G) are obtained and analyzed in comparison with the available theoretical and experimental data. For the first time numerical estimates of a set of elastic parameters of the polycrystalline MB2 ceramics (in the framework of the Voigt-Reuss-Hill approximation), namely bulk and shear modules, compressibility, Young's modules, Poisson's ratio, Lame's coefficients are performed.

cond-mat.mtrl-sci↗

arXiv2008

Elastic properties of quaternary oxyarsenide LaOFeAs as basic phase for new 26-52K superconductors

The full-potential linearized augmented plane wave (FP-LAPW) method with the generalized gradient approximation (GGA) for the exchange-correlation potential has been applied to predict the elastic properties of quaternary oxyarsenide LaOFeAs - the basic phase for the newly discovered 26-52K superconductors. The optimized lattice parameters, independent elastic constants (Cij), bulk modulus B, compressibility betta, and shear modulus G are evaluated and discussed. For the first time the numerical estimates of the elastic parameters for polycrystalline LaOFeAs ceramics are performed. Our analysis shows that LaOFeAs belong to the anisotropic mechanically stable systems; a parameter limiting the mechanical stability of this material is the shear modulus. In addition, LaOFeAs is a soft material (B -98 GPa) with high compressibility (betta - 0.0102 1/GPa); lays at the border of a brittle behavior and adopts a high ionic contribution in intra-atomic bonding.

cond-mat.supr-con↗