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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Draganyuk O. N., Zamkova N. G., Zhandun V. S.
Заглавие : Effect of substitution of Mn and Ga atoms by Fe atom in the Mn2GaC MAX phase
Место публикации : J. Magn. Magn. Mater. - 2022. - Vol. 563. - Ст.169860. - ISSN 03048853 (ISSN), DOI 10.1016/j.jmmm.2022.169860
Примечания : Cited References: 40. - The reported study was funded by Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science to the research project № 20-42-240004: “The effect of the composition, pressure, and dimension on the magnetic, electronic, optical, and elastic properties of the magnetic M n+1 AX n (M = Cr, Mn; Fe, A = Al, Ga, Si, Ge, P, In; X = C, N; n = 1-3) MAX-phases”. The calculations were performed with the computer resources of “Complex modeling and data processing research installations of mega-class” SRC “Kurchatovsky Institute” ( http://ckp.urcki.ru ). The ternary phase diagrams for the calculation of formation enthalpies were taken from Materials Project ( https://materialsproject.org ) and OQMD ( https://oqmd.org/ ) databases
Аннотация: The magnetic properties of ordered and disordered MAX-phase Mn2-xFe2xGaC and Mn2Ga1-xFexC (x = 12.5, 25, and 50 at.%) have been studied within DFT-GGA. The investigation of phase stability of M2AX phases is performed by comparing the total energy of MAX phases to that of the set of competitive phases for calculation of the phase formation enthalpy. At the small concentration of Fe atoms (x = 12.5 %) compound remains stable. We have found that introducing Fe atom at A-site leads to the forming of ferromagnetic phase with large magnetic moments on magnetic atoms and magnetization. Through detailed group-theoretical analysis we have obtained that only ferromagnetic ordering is possible when Fe atom ordering over Ga sites. The study of exchange constants shows that the out-of-plane Fe-Mn exchange gives the main contribution in appearance of ferromagnetic phase. The temperature dependences of magnetization reveal the increase of Curie temperature in Mn2GaC with Fe atom incorporated into Ga-site.
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Draganyuk O. N., Zhandun V. S., Zamkova N. G.
Заглавие : Effect of the Local Environment on the Magnetic Properties of Mn3Si: Hybrid Ab Initio and Model Study
Место публикации : Phys. Status Solidi B. - 2019. - Vol. 256, Is. 12. - Ст.1900228. - ISSN 03701972 (ISSN), DOI 10.1002/pssb.201900228
Примечания : Cited References: 34. - The reported study was funded by Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science to the research Project No. 18‐42‐243019: “First‐principles studies of the polarization, magnetic, electronic, and magnetoelectric properties of functional compounds with a spinel structure containing 3d and 4f ions.”
Аннотация: The effect of the local environment on the formation of magnetic moments on Mn atoms in manganese silicide Mn3Si is studied by the combination of ab initio calculations and the model analysis. The suggested approach is related to the self-consistent mapping of the results of ab initio calculations to a multiorbital model. The model analysis allows to reveal the role played by the local environment of the transition metal atoms on the magnetic moments formation. It is found that the formation of the magnetic moment is controlled rather by hopping parameters between Mn atoms, not by the number of Mn–Si nearest neighbors. Particularly, the formation of magnetic moment on MnI atom is mainly controlled by the hopping parameter between nearest Mn atoms, while the magnetic moment on MnII atom is primarily determined by the hoppings between next-nearest Mn atoms. The obtained phase diagrams of the magnetic state show the presence of a sharp boundary with respect to the hopping between Mn atoms. This opens the opportunity to turn on or turn off the magnetic state by the external impacts. The ab initio calculations of Mn3Si well agree with the results of model consideration and confirm the model conclusions.
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Draganyuk O. N., Zhandun V. S., Zamkova N. G.
Заглавие : Half-metallicity in Fe2MnSi and Mn2FeSi heusler compounds: A comparative ab initio study
Место публикации : Mater. Chem. Phys. - 2021. - Vol. 271. - Ст.124897. - ISSN 02540584 (ISSN), DOI 10.1016/j.matchemphys.2021.124897
Примечания : Cited References: 33. - The reported study was funded by Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science to the research projects No19-42-240016: «Control of structural, magnetic, electronic, and optical properties by pressure and intercalation into functional compounds with a spinel structure containing 3d and 4f ions» and 20-42-240004: “The effect of the composition, pressure, and dimension on the magnetic, electronic, optical, and elastic properties of the magnetic Mn+1AXn (M = Cr, Mn; Fe, A = Al, Ga, Si, Ge, P, In; X = C, N; n = 1–3) MAX-phases”. The calculations were performed with the computer resources of “Complex modeling and data processing research installations of mega-class” SRC “Kurchatovsky Institute” (http://ckp.urcki.ru)
Аннотация: First-principles calculations of the structural, electronic, and magnetic properties of full-Heusler compounds Fe2MnSi and Mn2FeSi in regular L21 and inverse XA structures have been performed using density functional theory (DFT) within generalized gradient approximation (GGA) and SCAN functionals. All compounds indicate half-metallic properties with the minority spin bandgap. The causes for the appearance of half-metallic bandgap and the difference in the electronic and magnetic properties of Heusler compounds were studied and analyzed in terms of the local environment. It is shown, that the half-metallic bandgap determines by the behavior of the t2g-electrons of A- and C-sites atoms. The behavior of the compounds under pressure was also considered. The high sensitivity of the magnetic moments on atoms A, C and the bandgap to pressure is discussed. The transition from regular to inverse structure is predicted at the negative pressure.
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4.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Draganyuk O. N., Zamkova N. G., Zhandun V. S.
Заглавие : The formation of ferromagnetic order in the fE-doped max phase Mn2GaC
Коллективы : Российская академия наук, Физико-технический институт им. Е.К. Завойского ФИЦ Казанского научного центра РАН, Казанский (Приволжский) федеральный университет, Euro-Asian Symposium "Trends in MAGnetism", "Trends in MAGnetism", Euro-Asian Symposium
Место публикации : VIII Euro-Asian symposium "Trends in magnetism" (EASTMAG-2022): Book of abstracts/ program com. S. G. Ovchinnikov [et al.]. - 2022. - Vol. 2, Sect. O: MAX materials. - Ст.O.O2. - P.480-481. - ISBN 978-5-94469-051-7
Примечания : Cited References: 3. - The reported study was funded by Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science to the research project № 20-42-240004
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sandalov I. S., Zamkova N. G., Zhandun V. S., Tarasov I. A., Varnakov S. N., Yakovlev I. A., Solovyov L. A., Ovchinnikov S. G.
Заглавие : Effect of electron correlations on the Fe3Si and α- FeSi2 band structure and optical properties
Коллективы : Russian Fund of Basic Research [14002-00186, 13-02-01265]; President of Russia Grants [2886.2014.2, 924.2014.2]
Место публикации : Phys. Rev. B: American Physical Society, 2015. - Vol. 92, Is. 20. - Ст.205129. - ISSN 1098-0121, DOI 10.1103/PhysRevB.92.205129. - ISSN 1550-235X(eISSN)
Примечания : Cited References:69. - The theoretical part of this work was supported by Russian Fund of Basic Research, Grant No. 14002-00186 and the President of Russia Grants No. 2886.2014.2 and No. 924.2014.2 for support of Leading Scientific School. The calculations were performed with the computer resources of NRC "Kurchatov Institute" (ui2.computing.kiae.ru). The experimental work was supported by Russian Fund of Basic Research, Grant No. 13-02-01265. I.S. thanks A. Ruban for useful discussion.
Предметные рубрики: DENSITY-FUNCTIONAL THEORY
TOTAL-ENERGY CALCULATIONS
AUGMENTED-WAVE METHOD
BASIS-SET
METALS
ABSORPTION
EMISSION
SURFACES
ALLOYS
LAYERS
Аннотация: We use the Vienna ab initio simulation package (vasp) for evaluation of the quasiparticle spectra and their spectral weights within Hedin's GW approximation (GWA) for Fe3Si and α-FeSi2 within the non-self-consistent one-shot approximation G0W0 and self-consistent scGWA with the vertex corrections in the particle-hole channel, taken in the form of two-point kernel. As input for G0W0, the band structure and wave functions evaluated within the generalized gradient corrected local-density approximation to density functional theory (GGA) have been used. The spectral weights of quasiparticles in these compounds deviate from unity everywhere and show nonmonotonic behavior in those parts of bands where the delocalized states contribute to their formation. The G0W0 and scGWA spectral weights are the same within 2%–5%. The scGWA shows a general tendency to return G0W0 bands to their GGA positions for the delocalized states, while in the flat bands it flattens even more. Variable angle spectroscopic ellipsometry measurements at T=296 K on grown single-crystalline ∼50-nm-thick films of Fe3Si on n-Si(111) wafer have been performed in the interval of energies ω∼(1.3–5) eV. The comparison of G0W0 and scGW theory with experimental real and imaginary parts of permittivity, refractive index, extinction and absorption coefficients, reflectivity, and electron energy loss function shows that both G0W0 and scGW qualitatively describe experiment correctly, the position of the low-energy peaks is described better by the scGW theory, however, its detailed structure is not observed in the experimental curves. We suggest that the angle-resolved photoemission spectroscopy experiments, which can reveal the fine details of the quasiparticle band structure and spectral weights, could help to understand (i) if the scGWA with this type of vertex correction is sufficiently good for description of these iron silicides and, possibly, (ii) why some features of calculated permittivity are not seen in optical experiments.
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zamkova N. G., Zhandun V. S., Ovchinnikov S. G., Sandalov I. S.
Заглавие : Effect of local environment on moment formation in iron silicides
Место публикации : J. Alloys Compd.: Elsevier, 2017. - Vol. 695. - P.1213-1222. - ISSN 09258388 (ISSN), DOI 10.1016/j.jallcom.2016.10.248
Примечания : Cited References: 40. - This work was supported by the Grants of Russian Foundation for Basic Research № 14-02-00186, № 17-02-00161 and by the Grants of Russian Foundation for Basic Research and Government of Krasnoyarsk Territory № 16-42-243035, 16-42-242036. The authors would like to thank AS Shinkorenko for the technical support.
Ключевые слова (''Своб.индексиров.''): ab initio calculations--iron silicides--magnetic properties--multiorbital model--spin-crossover
Аннотация: he effect of local environment on the formation of magnetic moments on Fe atoms in iron silicides is studied by combination of ab initio and model calculations. The suggested model includes all Fe d- and Si p-orbitals, intra-atomic Coulomb interactions, inter-atomic Fe-Fe exchange and hopping of electrons to nearest and next nearest neighboring atoms. The parameters of the model are found from the requirement that self-consistent moments on atoms and density of states found from ab initio and model calculations within the Hartree-Fock approximation are close to each other as much as possible. Contrary to the commonly accepted statement that in the ordered Fe3Si and FexSi1−x alloys an increase of the Si concentration within nearest environment of Fe atoms results in a decrease of Fe magnetic moment we find that a crucial role in the formation of magnetic moments is played by the second coordination sphere of Fe atoms. Particularly, the Fe atoms have higher magnetic moments in amorphous films compared to the epitaxial ones due to decreasing the number of iron-atoms in the next nearest environment. Both our model and ab initio calculations confirm existence of known spin crossover with pressure and predict second crossover at higher pressure.
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7.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Zamkova N.G., Zhandun V.S., Zinenko V.I.
Заглавие : Effect of Sr2+ ion substitution by the triva- lent ions (Sc3+,In3+,La3+,Bi3+) on the ferroelectric instability in SrTi03
Коллективы : European Meeting on Ferroelectricity
Место публикации : 12th European Meeting on Ferroelectricity: Abstracts. - 2011. - Ст.1-4
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8.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Zhandun V. S., Zamkova N. G., Maximova O. A., Lyashchenko S. A., Vysotin M. A., Sandalov I. S.
Заглавие : Electronic structure and magnetic properties of iron silicides
Коллективы : Asian School-Conference on Physics and Technology of Nanostructured Materials, Азиатская школа-конференция по физике и технологии наноструктурированных материалов
Место публикации : The Fifth Asian School-Conference on Physics and Technology of Nanostructured Materials: Proceedings. - VLadivostok: Dalnauka Publishing, 2020. - Ст.PS.03.04i. - P.26. - ISBN 978-5-8044-1698-1
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9.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Tarasov I. A., Yakovlev I. A., Volochaev M. N., Kuzubov A. A., Zamkova N. G., Kosyrev N. N., Velikanov D. A., Shemukhin A. A., Varnakov S. N., Ovchinnikov S. G.
Заглавие : Examination of structure, optical and magnetic properties of epitaxial Fe1–xSix/Si(111) alloy films
Коллективы : Euro-Asian Symposium "Trends in MAGnetism", "Trends in MAGnetism", Euro-Asian Symposium, Институт физики им. Л.В. Киренского Сибирского отделения РАН
Место публикации : VI Euro-Asian Symposium "Trends in MAGnetism" (EASTMAG-2016): abstracts/ ed.: O. A. Maksimova, R. D. Ivantsov. - Krasnoyarsk: KIP RAS SB, 2016. - Ст.O10.20. - P.464. - ISBN 978-5-904603-06-9 (Шифр -478014040)
Примечания : References: 1. - The work was supported by State contract No. 02.G25.31.0043, State task No.16.663.2014К, the Complex program of SB RAS № II.2P, project 0358-2015-0007
Ключевые слова (''Своб.индексиров.''): epitaxy--iron silicides--optical and magnetic properties--structure, defects
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zinenko V. I., Zamkova N. G., Zhandun V. S., Pavlovskii M. S.
Заглавие : Ferroelectric and structural instability in double perovskites Me1+Bi3+Me3+Nb5+O6 (Me1+ = Na, K, Rb; Me3+ = Sc, Ga, In, Lu)
Место публикации : J. Exp. Theor. Phys.: MAIK Nauka-Interperiodica / Springer, 2012. - Vol. 114, Is. 6. - P.955-962. - ISSN 1063-7761, DOI 10.1134/S1063776112040188
Примечания : Cited References: 7. - This work was supported by the Russian Foundation for Basic Research (project no. 09-02-00067) and by the program for the support of leading scientific schools (project no. NSh-4645.2010.2).
Аннотация: Within the Gordon-Kim generalized model with regard to the polarizabilities of ions, the lattice constants, the high-frequency permittivity, the Born dynamic charges, and the vibration constants of the crystal lattice are calculated for cation-ordered double perovskites Me1+Bi3+Me3+Nb5+O6. The vibration spectra of all the compounds exhibit two types of instabilities: instability associated with the rotation of the oxygen octahedron and ferroelectric instability. Various combinations of distortions with respect to the rotation mode yield five energetically most favorable distorted phases. The symmetry and the energy characteristics of these phases are discussed. In four of the five phases, the distortions associated with the oxygen octahedron rotation lead to polar phases, thus allowing one to speak of improper ferroelectricity in these compounds. One phase turns out to be nonpolar; however, it contains unstable polar modes such that a displacement along the eigenvectors of these modes gives rise to polarization in the crystal.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Vtyurin A. N., Goryainov S. V., Zamkova N. G., Zinenko V. I., Krylov A. S., Krylova S. N., Shefer A. D.
Заглавие : Hydrostatic pressure-induced phase transitions in RbMnCl3: Raman spectra and lattice dynamics
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2004. - Vol. 46, Is. 7. - P1301-1310. - ISSN 1063-7834, DOI 10.1134/1.1778456
Примечания : Cited References: 16
Предметные рубрики: CRYSTALS
SPECTROSCOPY
Аннотация: Raman scattering spectra of RbMnCl3 are measured at room temperature under high hydrostatic pressure. The results are interpreted based on first principles lattice dynamics calculations. The experimental data obtained correlate with the calculations in the low frequency domain but disagree slightly in the region of high-frequency vibrations. The transition from the hexagonal to the cubic perovskite phase observed earlier (near 0.7 GPa) was confirmed, and new transitions to lower symmetry distorted phases were discovered (at 1.1 and 5 GPa). (C) 2004 MAIK "Nauka / Interperiodica".
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhandun V. S., Zamkova N. G., Korzhavyi, Pavel, Sandalov I. S.
Заглавие : Inducing magnetism in non-magnetic α-FeSi2 by distortions and/or intercalations
Коллективы : Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science [17-42-240212, 18-42-243019]
Место публикации : Phys. Chem. Chem. Phys. - 2019. - Vol. 21, Is. 25. - P.13835-13846. - ISSN 1463-9076, DOI 10.1039/c9cp02361e. - ISSN 1463-9084(eISSN)
Примечания : Cited References: 27. - The reported study was funded by the Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science to the research projects No 17-42-240212: "Quantum-mechanical simulation of the physical properties of correlated electron materials to improve their functional characteristics" and No 18-42-243019: "First-principles studies of the polarization, magnetic, electronic, and magnetoelectric properties of functional compounds with a spinel structure containing 3d and 4f ions".
Предметные рубрики: TOTAL-ENERGY CALCULATIONS
WAVE
FeSi2
Аннотация: By means of hybrid ab initio + model approach we show that the lattice distortions in non-magnetic α-FeSi2 can induce a magnetic state. However, we find that the distortions required for the appearance of magnetism in non-magnetic α-FeSi2 are too large to be achieved by experimental fabrication of thin films. For this reason we suggest a novel way to introduce magnetism in α-FeSi2 using “chemical pressure” that is, intercalating the α-FeSi2 films by light elements. Theoretical study of the distortions resulting from intercalation reveals that the most efficient intercalants for formation of magnetism and a high spin polarization are lithium, phosphorus and oxygen. Investigation of the dependency of the magnetic moments and spin polarisation on the intercalation atoms concentration shows that the spin polarization remains high even at small concentrations of intercalated atoms, which is extremely important for modern silicate technology.
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13.

Вид документа : Однотомное издание
Шифр издания :
Заглавие : International workshop on actual problems of condensed matter physics : Program. Book of abstracts
Выходные данные : Krasnoyarsk, 2017
Колич.характеристики :30 с
Коллективы : Federal Research Center KSC SB RAS, Kirensky Institute of Physics, Siberian Federal Univercity, International Workshop on Actual Problems of Condensed Matter Physics (27 Mar. - 1 Apr. 2017; Krasnoyarsk/ Cheremushki) :
Содержание : Magnetic and transport properties of the epitaxial Fe3Si film on a Si substrate/ I. A. Bondarev. The magnetic anisotropy of the Fe and Fe(1-x)Si(x) thin films depend on/ I. A. Yakovlev [и др.]. Inverted opals as the Josephson networks of weak links/ S. I. Popkov [и др.]. Electronic structure and Fermi surface within the cluster perturbation theory in X-operators representation/ S. Nikolaev, V. I. Kuz'min, S. G. Ovchinnikov. DFT investigation of electronic and optical magnetic properties of one dimensional transition metal halide structuresTmHaI3/ A. S. Fedorov [и др.]. Effect of interatomic exchange interaction on spin crossover and Mott-Hubbard transition under high pressure and the physical properties of the low Earth’s mantle/ S. G. Ovchinnikov [и др.]. Extremely high magnetic-field sensitivity of charge transport in the Mn/SiO2/p-Si hybrid structure/ I. A. Tarasov [и др.]. Marnetic-field sensitivity of charge transport in silicon-based hybrid structures/ N. V. Volkov [et al.]. Fabrication of multi-terminal planar devices based on epitaxial Fe1-xSix films grown on Si(111)/ A. V. Lukyanenko, A. S. Tarasov, I. A. Tarasov [et al.] ; A. V. Luyanenko [и др.]. Magnetic field-driven lateral photovoltaic effect in the Fe/SiO2/p-Si hibrid structure with the Scottky barrier/ M. V. Rautskii [и др.]. Small angle X-ray scattering and atomic structure of aptamer biomolecules/ R. Moryachkov [и др.]. Iron silicides and pure iron epitaxial and highly-textured nanostructures on silicon: growth and their physical properties/ I. A. Tarasov [и др.]. Magnetic nanoparticles and DNA-aptamers conjugates for diagnostics and therapy of cancer/ A. E. Sokolov [и др.]. The microscopic origin of ferromagnetism in Fe silicides/ I. S. Sandalov [и др.].
Материалы конференции
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Varnakov S. N., Lyashchenko S. A., Tarasov I. A., Yakovlev I. A., Popov E. A., Zharkov S. M., Velikanov D. A., Tarasov A. S., Zhandun V. S., Zamkova N. G.
Заглавие : Iron silicide-based ferromagnetic metal/semiconductor nanostructures
Место публикации : Phys. Solid State: Maik Nauka-Interperiodica Publishing, 2016. - Vol. 58, Is. 11. - P.2277-2281. - ISSN 10637834 (ISSN), DOI 10.1134/S1063783416110299
Примечания : Cited References: 21. - The authors are very grateful to I.S. Sandalov for the useful discussion and the assistance in the interpretation of the obtained results.This work was supported by the Russian Science Foundation, project no. 16-13-00060.
Аннотация: Ferromagnetic single-crystal epitaxial Fe3Si films and polycrystalline Fe5Si3 films are obtained on Si substrates by molecular-beam epitaxy with in situ control of the structure, optical, and magnetic properties. The results of the structural, magnetic, and optical measurements are discussed. The experimental data are compared to the results of the microscopic calculation of the spin-polarized structure, the permittivity, and the optical conductivity spectra. © 2016, Pleiades Publishing, Ltd.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gavrichkov V. A., Shan'ko, Yury, Zamkova N. G., Bianconi A.
Заглавие : Is There Any Hidden Symmetry in the Stripe Structure of Perovskite High-Temperature Superconductors?
Коллективы : RFBR [18-42-240017]; Government of the Krasnoyarsk Region [18-42-240017]; Krasnoyarsk Regional Fund of Science [18-42-240017]
Место публикации : J. Phys. Chem. Lett. - 2019. - Vol. 10, Is. 8. - P.1840-1844. - ISSN 1948-7185, DOI 10.1021/acs.jpclett.9b00513
Примечания : Cited References: 68. - One of the authors (V.A.G.) is grateful to RFBR, the Government of the Krasnoyarsk Region and Krasnoyarsk Regional Fund of Science for the research Grant No. 18-42-240017
Предметные рубрики: T-C
CUO2 PLANE
INHOMOGENEOUS SUPERCONDUCTIVITY
PHASE-DIAGRAM
Аннотация: Local and fast structural probes using synchrotron radiation have shown nanoscale striped puddles and nanoscale phase separation in doped perovskites. It is known that the striped phases in doped perovskites are due to competing interactions involving charge, spin, and lattice degrees of freedom. In this work, we show that two different stripes can be represented as a superposition of a pair of stripes, U(θn) or D(θn), characterized by perovskite tilts where one of the pair is rotated in relation to the other partner by an angle Δθn = π/2. The spatial distribution of the U and D stripes is reduced to all possible maps in the well-known mathematical four-color theorem. Both the periodic striped puddles and random structures can be represented by using planar graphs with a chromatic number χ ≤ 4. To observe the colors in mapping experiments, it is necessary to recover variously oriented tilting effects from the replica. It is established that there is an interplay between the annihilation/creation of new stripes and ordering/disordering tilts in relation to the θn angle in the CuO2 plane, where the characteristic shape of the stripes coincides with the tilting-ordered regions.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhandun V. S., Zamkova N. G., Korzhavyi P., Sandalov I. S.
Заглавие : Lattice distortions and/or intercalation as ways to induce magnetism in a-FeSi2: a theoretical study
Место публикации : ArXiv. - 2018. - Ст.1805.06189
Примечания : Cited References: 20. - This work was supported by the Russian Fund for Basic Research, Government of Krasnoyarsk Territory and Krasnoyarsk Region Science and Technology Support Fund to the research Projects No 17-42-240212 and No 18-42-243019.
Аннотация: The possibilities to induce magnetism in the non-magnetic bulk α-FeSi2 by means of lattice distortions or intercalation with metal or non-metal ions of light elements is investigated theoretically by combined ab initio and model methods. We find that the distortions indeed can induce the formation of magnetic moment on iron atoms in certain local environments; however, the required strength of the distortions often is too large to be achieved in experiments. For this reason we suggest using "chemical pressure" that is, intercalating the α-FeSi2 films by light elements. We find that some of such variants have promising characteristic.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zinenko V. I., Zamkova N. G., Maksimov E. G., Sofronova S. N.
Заглавие : Lattice dynamics and ferroelectric instability in ordered and disordered PbSc1/2Ta1/2O3 and PbSc1/2Nb1/2O3 solid solutions
Разночтения заглавия :авие SCOPUS: Lattice dynamics and ferroelectric instability in ordered and disordered PbSc1/2Ta1/2O3 and PbSc1/2Nb 1/2O3 solid solutions
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2007. - Vol. 105, Is. 3. - P617-625. - ISSN 1063-7761, DOI 10.1134/S1063776107090191
Примечания : Cited References: 23
Предметные рубрики: RELAXOR FERROELECTRICS
PHASE-TRANSITION
LOCAL-STRUCTURE
PB(SC1/2NB1/2)O-3
PEROVSKITE
CRYSTALS
Ключевые слова (''Своб.индексиров.''): dipole moment--lattice vibrations--negative ions--phonons--positive ions--solid solutions--dynamic born charges--ferroelectric instabilities--frequency spectra--gordon-kim models--oxygen anions--phonon spectra--ferroelectricity
Аннотация: The dynamic Born charges and the frequency spectra of lattice oscillations in the crystals of ordered and disordered PbSc1/2Ta1/2O3 (PST) and PbSc1/2Nb1/2O3 (PSN) solid solutions have been calculated within the framework of the generalized Gordon-Kim model with allowance for the dipole and quadrupole polarizabilities. The phonon spectra of both compounds contain ferroelectric soft modes. The influence of various interactions on the magnitude of dynamic charges and ferroelectric instability in PSN and PST solid solutions has been studied and it is shown that both these charges and the ferroelectric instability are determined by the competition between long-range dipole-dipole interactions and short-range dipole-charge interactions, the determining role played by the interaction of Nb (Ta) cations and oxygen anions in the Nb-O (Ta-O) bond direction.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aleksandrov K. S., Voronov V. N., Vtyurin A. N., Goryainov S. V., Zamkova N. G., Zinenko V. I., Krylov A. S.
Заглавие : Lattice dynamics and hydrostatic-pressure-induced phase transitions in ScF3
Место публикации : J. Exp. Theor. Phys.: American Institute of Physics, 2002. - Vol. 94, Is. 5. - P.977-984. - ISSN 1063-7761, DOI 10.1134/1.1484991
Примечания : Cited References: 20
Предметные рубрики: RAMAN-SPECTROSCOPY
CRYSTALS
SCATTERING
Аннотация: New phase transitions induced by hydrostatic pressure in a cubic (under standard conditions) ScF3 crystal are discovered by the methods of polarization microscopy and Raman scattering. The space groups R (3) over barc for Z = 2 and Pnma for Z = 4 are proposed for the high-pressure phases. A nonempirical computation of the lattice dynamics of the crystal is carried out. It is shown that, under normal pressure, the cubic phase is stable down to T = 0 K, while the application of a hydrostatic pressure gives rise to a phonon branch in the vibrational spectrum (between points R and M of the Brillouin zone) with negative values of squares of frequencies. The condensation of soft mode R-5 at the boundary point of the Brillouin zone leads to rhombohedral distortion of the cubic structure with the unit cell volume doubling. The calculated frequencies at q = 0 of the ScF3 lattice in the distorted rhombohedral phase are real-valued; the number and position of frequencies active in Raman scattering are in accord with the experimental values. (C) 2002 MAIK "Nauka/Interperiodica".
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Krylova S. N., Vtyurin A. N., Bulou A., Krylov A. S., Zamkova N. G.
Заглавие : Lattice dynamics and raman scattering spectrum of elpasolite Rb2KScF6: Comparative analysis
Разночтения заглавия :авие SCOPUS: Lattice dynamics and Raman scattering spectrum of elpasolite Rb 2KScF6: Comparative analysis
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2004. - Vol. 46, Is. 7. - P1311-1319. - ISSN 1063-7834, DOI 10.1134/1.1778457
Примечания : Cited References: 18
Предметные рубрики: STRUCTURAL PHASE-TRANSITION
LIGHT-SCATTERING
OPTICAL PHONONS
SOFT-MODE
CRYSTAL
Аннотация: Raman scattering spectra of elpasolite Rb2KScF6 are studied in a wide temperature range including two phase transitions: from the cubic to the tetragonal phase and then to the monoclinic phase. The experimental Raman scattering spectrum is compared with the lattice vibration spectra of these phases calculated using an ab initio approach. A number of anomalies (caused by structural rearrangement during the phase transitions) are revealed and quantitatively analyzed in the ranges of both the intramolecular vibrations of the octahedron molecular ScF6 ions and low-frequency intermolecular lattice vibrations. The interaction between low-frequency intramolecular vibrations and the intermolecular modes is found to be significant, and strong resonance interaction of the rotational soft modes (which are recovered below the phase transition points) with hard low-frequency vibrations of the rubidium ion sublattice is detected. These interactions are shown to substantially complicate the spectra. (C) 2004 MAIK "Nauka / Interperiodica".
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Maksimov E. G., Zinenko V. I., Zamkova N. G.
Заглавие : Ab initio calculations of the physical properties of ionic crystals
Место публикации : Phys. Usp.: TURPION LTD, 2004. - Vol. 47, Is. 11. - P1075-1099. - ISSN 1063-7869, DOI 10.1070/PU2004v047n11ABEH001796
Примечания : Cited References: 90
Предметные рубрики: STRUCTURAL PHASE-TRANSITION
LOCAL-FIELD CORRECTIONS
INDUCED BREATHING MODEL
ZINC-BLENDE STRUCTURE
ELECTRON-GAS THEORY
LATTICE-DYNAMICS
MICROSCOPIC CALCULATIONS
MACROSCOPIC POLARIZATION
STATISTICAL-MECHANICS
1ST-PRINCIPLES THEORY
Аннотация: First-principles calculations of the physical properties of ionic crystals are reviewed. Two markedly different approaches within the framework of the density functional theory are described. In one of them, the electron spectrum and wave functions are treated within the standard band picture based on the solution of Kohn-Sham equations. In the second approach, the total electron density of a crystal is represented as a super-position of the densities of individual ions. The problem of determining the electric polarization of a crystal is discussed for each approach. It is shown that it is the use of Bloch functions rather than the physics of the phenomenon that complicates the solution of this problem within the Kohn-Sham framework. The deformable and polarizable ion model is described in detail, and its application to calculating many properties of ionic crystals, including the lattice dynamics and structural stability of crystal phases, is discussed.
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