Библиотека института физики им. Л.В. Киренского СО РАН

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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Krylova S. N., Gudim I. A., Aleksandrovsky A. S., Vtyurin A. N., Krylov A. S.
Заглавие : Electronic band structures of NdFe3(BO3)4 and NdGa3(BO3)4 crystals: ab initio calculations
Коллективы : Russian Foundation for Basic Research GrantRussian Foundation for Basic Research (RFBR) [20-42-240009]
Место публикации : Ferroelectrics. - 2021. - Vol. 575, Is. 1. - P.11-17. - ISSN 0015-0193, DOI 10.1080/00150193.2021.1888219. - ISSN 1563-5112(eISSN)
Примечания : Cited References: 27. - This work was supported by the Russian Foundation for Basic Research Grant No. 20-42-240009
Предметные рубрики: HOFE3(BO3)4
TEMPERATURE
SPECTRA
GROWTH
Аннотация: NdFe3(BO3)4 and NdGa3(BO3)4 crystals are of great interest due to their physical properties. For example, NdFe3(BO3)4 crystal demonstrates magnetodielectric and magnetopiezoelectric effects, and NdGa3(BO3)4 crystal possesses luminescent and nonlinear optical properties. In this work, the properties of these materials are calculated by the plane-wave pseudo-potential method based on density functional theory. The structures of the crystals are optimized. The electronic structure of NdFe3(BO3)4 and NdGa3(BO3)4 are calculated.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Krylov A. S., Krylova S. N., Gudim I. A., Vtyurin A. N.
Заглавие : Soft modes in HoFe2.5Ga0.5(BO3)4 solid solution
Коллективы : European Meeting on Ferroelectricity , Russian Foundation for Basic Research GrantRussian Foundation for Basic Research (RFBR) [1802-00754]
Место публикации : Ferroelectrics. - 2020. - Vol. 556, Is. 1. - P.16-22. - ISSN 0015-0193, DOI 10.1080/00150193.2020.1713334. - ISSN 1563-5112(eISSN)
Примечания : Cited References: 14. - This work was supported by the Russian Foundation for Basic Research Grant No 1802-00754.
Предметные рубрики: RAMAN-SCATTERING
SPECTRA
HO1-XNDXFE3(BO3)(4)
Аннотация: The condensation of two soft modes has been found when studying the Raman spectra of the solid solution HoFe2.5Ga0.5(BO3)4 in the temperature range from 7 to 350 K. The first high-temperature soft mode is associated with the structural phase transition from the R32 phase to the P3121 phase. The second soft mode is related to the reveal of the phonon-magnon interaction during magnetic ordering in the crystal. The temperatures of the structural phase transition T1 = 266 K and the magnetic phase transition T2 = 28 K are established. Experimentally interaction between the structural phase transition order parameter fluctuations and the magnetic order parameter fluctuations was found.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ignatchenko V. A., Tsikalov D. S.
Заглавие : Spin-wave resonance in gradient ferromagnets with concave and convex variations of magnetic parameters
Коллективы : Russian Foundation for Basic Research, Government of Krasnoyarsk Territory [18-42-243005]
Место публикации : J. Appl. Phys. - 2020. - Vol. 127, Is. 12. - Ст.123903. - ISSN 0021-8979, DOI 10.1063/1.5143499. - ISSN 1089-7550(eISSN)
Примечания : Cited References: 26. - This work was partially supported by the Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science to the research project (No. 18-42-243005) "Synthesis and investigation of magnetic properties of gradient materials that are characterized by predetermined type of the magnetic parameter change" and the Krasnoyarsk Regional Fund of Science in the framework of participation in the conference "VII Euro-Asian Symposium 'Trends in MAGnetism' (EASTMAG 2019)."
Предметные рубрики: SPECTRA
MODES
Аннотация: The theory of spin-wave resonance in gradient ferromagnetic films with magnetic parameters varying in space described by both concave and convex quadratic functions is developed. Gradient structures such as a potential well, a potential barrier, and a monotonic change in potential between the film surfaces for both quadratic functions are considered. The waveforms of oscillations mn(z), the laws of the dependence of discrete frequencies ωn, and relative susceptibilities χn/χ01 of spin-wave resonances on the resonance number n are studied. It is shown that the law ωn∝n for nnc, where nc is the resonance level near the upper edge of the gradient inhomogeneity, which is well known for a parabolic potential well, is also valid for the potential barrier and for the monotonic change in potential, if these structures are formed by a concave quadratic function. It is shown that the law ωn∝(n−1/2)1/2, which we numerically derived and approximated by the analytical formula, is valid for all three structures formed by a convex quadratic function. It is shown that the magnetic susceptibility χn of spin-wave resonances for nnc is much greater than the susceptibility of resonances in a uniform film. An experimental study of both laws ωn(n) and χn(n) would allow one to determine the type of quadratic function that formed the gradient structure and the form of this structure. The possibility of creating gradient films with different laws ωn(n) and the high magnitude of the high-frequency magnetic susceptibility χn(n) at nnc make these metamaterials promising for practical applications.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Oreshonkov A. S., Shestakov N. P., Molokeev M. S., Aleksandrovsky A. S., Gudim I. A., Temerov V. L., Adichtchev S. V., Pugachev A. M., Nemtsev I. V., Pogoreltsev E. I., Denisenko Y. G.
Заглавие : Monoclinic SmAl3(BO3)4: synthesis, structural and spectroscopic properties
Коллективы : Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR) [18-03-00750, 18-05-00682, 18-32-20011]
Место публикации : Acta Crystallogr. B. - 2020. - Vol. 76. - P.654-660. - ISSN 2052-5206(eISSN), DOI 10.1107/S2052520620008781
Примечания : Cited References: 38. - Funding for this research was provided by: Russian Foundation for Basic Research (grant Nos. 18-03-00750, 18-05-00682 and 18-32-20011 to AO)
Предметные рубрики: Optical-properties
Luminescence
Spectra
Crystals
Sm
Аннотация: Single crystals of SmAl3(BO3)4 were synthesized by the group growth on seeds method. The crystal structure was solved using a single-crystal experiment and the purity of the bulk material was proved by the Rietveld method. This borate crystallizes in the monoclinic C2/c space group with unit-cell parameters a = 7.2386 (3), b = 9.3412 (5), c = 11.1013 (4) Å and β = 103.2240 (10)°. IR and Raman spectroscopic analyses confirmed the monoclinic structure of SmAl3(BO3)4. Under 532.1 nm excitation, luminescence spectra exhibit bands assignable to the transitions from 4G5/2 to 6H5/2, 6H7/2, 6H9/2 and 6H11/2. The similarity of the luminescence spectra of the trigonal and monoclinic polymorphs is explained by the minor role of Sm—O bond distortion and the primary role of rotational distortion of SmO6 octahedra. The smaller covalency of the Sm—O bond in alumoborates is deduced in comparison with galloborates. Calorimetric measurements did not reveal high-temperature structural phase transitions up to a temperature of 720 K.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ekholm V., Chiuzbaian G. S., Sathe C., Nicolaou A., Guarise M., Simon M., Jaouen N., Luning J., Hague C. F., Gel'mukhanov F., Odelius M., Bjorneholm O., Rubensson, J-E
Заглавие : Core-hole localization and ultra-fast dissociation in SF6
Коллективы : Swedish Research Council (VR)Swedish Research Council; Russian Science FoundationRussian Science Foundation (RSF) [16-12-10109]
Место публикации : J. Phys. B. - 2020. - Vol. 53, Is. 18. - Ст.185101. - ISSN 0953-4075, DOI 10.1088/1361-6455/aba204. - ISSN 1361-6455(eISSN)
Примечания : Cited References: 36. - This work was supported by the Swedish Research Council (VR). The calculations were performed on resources provided by the Swedish National Infrastructure for Computing (SNIC). FG acknowledges support within the Russian Science Foundation (Project No. 16-12-10109)
Предметные рубрики: X-RAY-EMISSION
SYMMETRY-BREAKING
AB-INITIO
SPECTROSCOPY
SPECTRA
Аннотация: Resonant inelastic x-ray scattering spectra excited at the fluorine K resonances of SF6 have been recorded. While a small but significant propensity for electronically parity-allowed transitions is found, the observation of parity-forbidden electronic transitions is attributed to vibronic coupling that breaks the global inversion symmetry of the electronic wavefunction and localizes the core hole. The dependence of the scattering cross section on the polarization of the incident radiation and the scattering angle is interpreted in terms of local π/σ symmetry around the S–F bond. This symmetry selectivity prevails during the dissociation that occurs during the scattering process.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shtarev D. S., Shtareva, A., V, Kevorkyants R., Rudakova, A., V, Molokeev M. S., Bakiev, T., V, Bulanin K. M., Ryabchuk V. K., Serpone N.
Заглавие : Materials synthesis, characterization and DFT calculations of the visible-light-active perovskite-like barium bismuthate Ba1.264(4)Bi1.971(4)O4 photocatalyst
Коллективы : Russian Science FoundationRussian Science Foundation (RSF) [19-73-10013]; Saint-Petersburg State University [39054581]; Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR) [18-03-00855]
Место публикации : J. Mater. Chem. C. - 2020. - Vol. 8, Is. 10. - P.3509-3519. - ISSN 2050-7526, DOI 10.1039/c9tc06457e. - ISSN 2050-7534(eISSN)
Примечания : Cited References: 42. - The current research was kindly funded by a grant from the Russian Science Foundation (project No. 19-73-10013). R. K., A. V. R., V. K. R. and T. V. B. acknowledge financial support from Saint-Petersburg State University (Pure ID 39054581). A. V. R. thanks the Russian Foundation for Basic Research for a Grant No. 18-03-00855 that supported studies into the photoinduced hydrophilicity of the bismuthate. The authors are further grateful to the staff of the Khabarovsk Innovation and Analytical Center of the Yu. A. Kosygin Institute of Tectonics and Geophysics of the Far Eastern Branch of the Russian Academy of Sciences, and the Resource Centers of the Research Park at the Saint-Petersburg State University: (i) the Center for Diagnostics of Functional Materials for Medicine, Pharmacology and Nanoelectronics, (ii) the Center for Physical Methods of Surface Investigation, (iii) the Center for Optical and Laser Materials Research, and the laboratories of (iv) Nanotechnology and (v) Nanophotonics for their valuable assistance in carrying out the research and in providing the needed equipment. One of us (N.S.) is grateful to Prof. Angelo Albini and the staff of the PhotoGreen Laboratory at the University of Pavia, Italy, for their continued hospitality.
Предметные рубрики: OXIDE
NIO/SRBI2O4
SPECTRA
DRIVEN
CO2
LA
Аннотация: A perovskite-like barium bismuthate of the BaBi2O4 class, Ba1.264(4)Bi1.971(4)O4, has been prepared by solid-state synthesis and subsequently characterized by a number of experimental techniques (XPS, DRS, SEM, EDX and Raman spectroscopy), as well as by a DFT computational approach using the GGA Perdew–Burke–Ernzerhof (PBE) density functional to determine the energy band structure. XRD peaks were indexed to a rhombohedral cell (R[3 with combining macron]m) with parameters close to Ba0.156Bi0.844O1.422 (i.e., to Ba0.439Bi2.374O4), which upon Rietveld refinement gave Ba1.264(4)Bi1.971(4)O4. The Bi–O bond lengths determined from this refinement (1.86 and 2.31 Å) accorded with the bond lengths estimated from Raman spectra (1.97 and 2.26 Å). DFT calculations revealed the bismuthate to display two bandgaps that correspond to lower-energy indirect (2.28 eV) and to higher-energy direct (2.36 eV) electronic transitions in good agreement with the experimental bandgaps of 2.26 eV and 2.43 eV, respectively, from Tauc plots of DRS spectra. Relative to the indirect bandgap energy of 2.26 eV, the energies of the valence band and of the conduction band were, respectively, +1.14 eV and −1.12 eV. The photoactivity of Ba1.264(4)Bi1.971(4)O4 was examined toward the photoreduction of the greenhouse gas CO2 in aqueous media photoelectrochemically yielding alcohols and alkanes, while in the gas phase in an infrared cell reactor the products were carbon monoxide and alkanes.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shi, Xin, Wu, Yong, Wang, Jian Guo, Kimberg V., Zhang, Song Bin
Заглавие : X-ray transient absorption spectroscopy by an ultrashort x-ray-laser pulse in a continuous-wave IR field
Место публикации : Phys. Rev. A. - 2020. - Vol. 101, Is. 2. - Ст.023401. - ISSN 2469-9926, DOI 10.1103/PhysRevA.101.023401. - ISSN 2469-9934(eISSN)
Примечания : Cited References: 56. - Grants from the National Basic Research Program of China (Grant No. 2017YFA0403200), National Natural Science Foundation of China (Grants No. 11604197, No. 11934004, and No. 11974230), the Science Challenge Program of China (Grants No. TZ2018005 and No. TZ2016005), and the Organization Department of CCCPC are acknowledged. V.K. acknowledges financial support from Swedish Research Council within the State Contract of the Ministry of Education and Science of the Russian Federation for Siberian Federal University for Scientific Research in 2017-2019 (Project No. 3.2662.2017)
Предметные рубрики: MOLECULAR NITROGEN
TIME
DYNAMICS
PHASE
SPECTRA
DECAY
Аннотация: X-ray transient absorption spectra (XTAS) of molecules are theoretically investigated in a femtosecond x-ray pump and continuous-wave (cw) infrared (IR)-control scenario. The scheme is exemplified by a CO molecule resonantly pumped into carbon and oxygen core-excited 1s→π∗ states by a weak femtosecond x-ray pulse, while dynamic Stark shifts are induced by the cw IR-control radiation. As a result, significant shoulder structures appear in XTAS showing strong dependence on the phase of IR radiation relative to the envelope of the x-ray pulse. Due to a significant difference in the frequencies of the two pulses, the present XTAS scheme provides much clear interpretation of the dynamic Stark effects as compared to the attosecond UV transient absorption scenario. Within the suggested two-level model, where the total spectrum is decomposed as incoherent superposition of contributions from different vibrational excitations weighted by the Franck-Condon Factors, all spectral structures can be well identified and interpreted in a good agreement with the full-scale molecular simulations. Well-characterized XTAS in the proposed IR-control scheme can be applied for fine phase synchronization between IR and x-ray pulses, highly demanded in modern experiments on x-ray free-electron lasers.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Belyaev B. A., Drokin N. A., Poluboyarov V. A.
Заглавие : Impedance spectroscopy study of the electrical properties of cation-substituted barium hexaaluminate ceramics
Место публикации : Phys. Solid State. - 2018. - Vol. 60, Is. 2. - P.274-280. - ISSN 1063-7834, DOI 10.1134/S1063783418020063. - ISSN 1090-6460(eISSN)
Примечания : Cited References:18
Предметные рубрики: DIELECTRIC-RELAXATION
LIQUID-CRYSTALS
SPECTRA
Аннотация: We report on the behavior of frequency and temperature dependences of the impedance of a measuring cell in the form of a parallel-plate capacitor filled with barium hexaaluminate ceramics with four aluminum cations replaced by iron (BaO · 2Fe2O3 · 4Al2O3). The measurements have been performed in the frequency range of 0.5–108 Hz at temperatures of 20-375°C. A technique for determining the electrical properties of the investigated ceramics is proposed, which is based on an equivalent electric circuit allowing the recorded impedance spectra to be approximated with sufficiently high accuracy. The established spectral features are indicative of the presence of two electric relaxation times different from each other by three orders of magnitude. This fact is explained by the difference between the charge transport processes in the bulk of crystallites and thin intercrystallite spacers, for which the charge activation energies have been determined.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zobov V. E., Kucherov M. M.
Заглавие : On the effect of an inhomogeneous magnetic field on high-frequency asymptotic behaviors of correlation functions of spin lattices
Место публикации : JETP Letters. - 2018. - Vol. 107, Is. 9. - P.553-557. - ISSN 0021-3640, DOI 10.1134/S002136401809014X. - ISSN 1090-6487(eISSN)
Примечания : Cited References: 39
Предметные рубрики: HEISENBERG PARAMAGNET
SYSTEMS
TIME
RELAXATION
DYNAMICS
SPECTRA
Аннотация: Singular points of spin autocorrelation functions on the imaginary time axis, which determine the arguments of exponential high-frequency asymptotic behaviors, have been analyzed. It has been shown that randomly distributed inhomogeneous magnetic fields expand the wings of spectra of autocorrelation functions and, thereby, intensify the heating of a system subjected to variable magnetic fields, which are used to create effective Hamiltonians or at the saturation of inhomogeneously broadened EPR lines.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Parshin A. S., Igumenov, A. Yu., Mikhlin, Yu. L., Pchelyakov O. P., Zhigalov V. S.
Заглавие : Reflection electron energy loss spectroscopy of iron monosilicide
Место публикации : Russ. Phys. J.: Springer, 2017. - Vol. 59, Is. 10. - P.1610-1615. - ISSN 1064-8887, DOI 10.1007/s11182-017-0952-7. - ISSN 1573-9228(eISSN)
Примечания : Cited References:14
Предметные рубрики: SCATTERING CROSS-SECTION
SPECTRA
Ключевые слова (''Своб.индексиров.''): iron silicides--iron monosilicide--inelastic electron scattering cross--section spectroscopy--reflection electron energy loss spectroscopy--x-ray photoelectron spectroscopy
Аннотация: X-ray photoelectron spectra, reflection electron energy loss spectra, and inelastic electron scattering cross section spectra of iron monosilicide FeSi are investigated. It is shown that the spectra of inelastic electron scattering cross section have advantages over the reflection electron energy loss spectra in studying the processes of electron energy losses. An analysis of the fine structure of the inelastic electron scattering cross section spectra allows previously unresolved peaks to be identified and their energy, intensity, and nature to be determined. The difference between energies of fitting loss peaks in the spectra of inelastic electron scattering cross section of FeSi and pure Fe are more substantial than the chemical shifts in X-ray photoelectron spectra, which indicates the possibility of application of the fine structure of the spectra of inelastic electron scattering cross section for elemental analysis.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Li O. A., Lin C. -R., Chen H. -Y., Hsu, Hua-Shu, Shih K. -Y., Edelman I. S., Wu K. -W., Tseng Y. -T., Ovchinnikov S. G., Lee J. -S.
Заглавие : Size dependent magnetic and magneto-optical properties of Ni0.2Zn0.8Fe2O4 nanoparticles
Место публикации : J. Magn. Magn. Mater.: Elsevier, 2016. - Vol. 408. - P.206-212. - ISSN 03048853 (ISSN), DOI 10.1016/j.jmmm.2016.02.062
Примечания : Cited References: 51. - This work is supported by the Ministry of Science and Technology of Taiwan (MOST 103-2811-M-153 -001 and MOST 102-2112-M-153 -002 -MY3), and by the Russian Foundation for Basic Researches, grant No 14-02-01211.
Предметные рубрики: Zinc ferrite
Cation distribution
Sol-gel
Ni
ZnFe2O4
Spinel
Fe3O4
Particles
Spectra
State
Ключевые слова (''Своб.индексиров.''): nickel zinc ferrite--nanoparticles--magnetic properties--mcd
Аннотация: Ni0.2Zn0.8Fe2O4 spinel nanoparticles have been synthesized by combustion method. Average particles size varies from 15.5 to 50.0 nm depending on annealing temperature. Correlations between particles size and magnetic and magneto-optical properties are investigated. Magnetization dependences on temperature and external magnetic field correspond to the sum of paramagnetic and superparamagnetic response. Critical size of single-domain transition is found to be 15.9 nm. Magnetic circular dichroism (MCD) studies of nickel zinc spinel are presented here for the first time. The features in magnetic circular dichroism spectrum are assigned to the one-ion d-d transitions in Fe3+ and Ni2+ ions, as well to the intersublattice and intervalence charge transfer transitions. The MCD spectrum rearrangement was revealed with the change of the nanoparticles size. © 2016 Elsevier B.V. All rights reserved.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gorev M. V., Flerov I. N., Tressaud A., Bogdanov E. V., Kartashev A. V., Bayukov O. A., Eremin E. V., Krylov A. S.
Заглавие : Heat capacity and magnetic properties of fluoride CsFe2+Fe3+F6 with defect pyrochlore structure
Место публикации : J. Solid State Chem. - 2016. - Vol. 237. - P.330-335. - ISSN 00224596 (ISSN), DOI 10.1016/j.jssc.2016.02.045
Примечания : Cited References: 19. - This study was partially supported by the Grant NSh-924.2014.2 of the President of the Russian Federation for the Support of Leading Scientific Schools.
Предметные рубрики: Crystal-structure
Mossbauer
CsFe2F6
Spectra
Ключевые слова (''Своб.индексиров.''): pyrochlore structure--phase transition--magnetic properties--thermal properties
Аннотация: Heat capacity, Mossbauer and Raman spectra as well as magnetic properties of fluoride CsFe2F6 with defect pyrochlore structure were studied. In addition to recently found above room temperature three successive structural transformations Pnma-Imma-I41amd-Fd-3m, phase transition of antiferromagnetic nature with the 13.7 K Neel temperature and a broad heat capacity anomaly with a maximum at about 30 K were observed. The room temperature symmetry Pnma is unchanged at least down to 7 K. Simple model of indirect bond used to estimate the exchange interactions and to propose a magnetic structure model. © 2016 Elsevier Inc. All rights reserved.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sobol A. A., Shukshin V. E., Zaitsev A. I.
Заглавие : Raman spectroscopy of SrB4O7 single crystals in the temperature range 300–1273 K
Место публикации : Opt. Spectrosc.: MAIK Nauka-Interperiodica / Springer, 2016. - Vol. 121, Is. 1. - P.25-31. - ISSN 0030400X (ISSN), DOI 10.1134/S0030400X16070201
Примечания : Cited References: 20. - This work was supported by the Russian Foundation for Basic Research, project no. 13-02-00707a.
Предметные рубрики: STRONTIUM TETRABORATE
PHASE-TRANSITIONS
SCATTERING
SPECTRA
Аннотация: The polarized Raman spectra of SrB4O7 (SBO) single crystals are studied in detail in the temperature range of 300–1273 K. The TO, LO, and IO phonon lines of A1, A2, B1, and B2 symmetries of rhombic SBO at 300 K are identified. The behavior of the Raman spectra of SBO crystals is studied upon heating up to their melting. The relation of Raman spectra with the structure of boron–oxygen fragments, as well as the transformation of spectra in the process of melting of SBO crystals, is discussed. © 2016, Pleiades Publishing, Ltd.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Lyubutin I. S., Korotkov, N. Yu., Frolov K. V., Kazak N. V., Platunov M. S., Knyazev, Yu. V., Bezmaternykh L. N., Ovchinnikov S. G., Arauzo A., Bartolome J.
Заглавие : Spin-glass behavior of warwickite MgFeBO4 and CoFeBO4 crystals observed by Mössbauer spectroscopy
Место публикации : J. Alloys Compd.: Elsevier Science, 2015. - Vol. 642. - P.204-209. - ISSN 0925, DOI 10.1016/j.jallcom.2015.04.067. - ISSN 18734669(eISSN)
Примечания : Cited References:29. - This study was supported by the Russian Foundation for Basic Research (Grants # 14-02-00483a, 14-02-31051-mol-a, 13-02-00958- a, and 13-02-00358-a), by the Council for Grants of the President of the Russian Federation (Project Nos. NSh-2886.2014.2 and SP-938.2015.5), by the Grant of KSAI, Krasnoyarsk regional fund of supporting scientific and technological activities and by the program of Foundation for Promotion of Small Enterprises in Science and Technology (''UMNIK'' program). The Spanish MINECO project MAT2011/23791, MAT2014/53921 and DGA E-34 are acknowledged.
Предметные рубрики: SOLVABLE MODEL
SPECTRA
Ключевые слова (''Своб.индексиров.''): warwickites--spin-glass--mossbauer spectroscopy
Аннотация: Single crystals of MgFeBO4 and СоFeBO4 warwickites were obtained. The effects of charge ordering and magnetic properties were investigated by Mössbauer spectroscopy. Cation distribution over M1 and M2 nonequivalent sites and the average charge at the metal positions were established. Low temperature Mössbauer spectra reveal spin-glass behavior, with spin-freezing temperatures TSG of 15.2 and 33.2 K for Mg- and Co-warwickites, respectively, higher than that observed from the d.c. and a.c. magnetic susceptibility measurements. The difference is explained in terms of dynamical scaling theory. The specific shape of the Mössbauer spectra in the vicinity of the magnetic transition at TSG shows the difference between spin-glass and superparamagnetic behavior and demonstrates an overwhelming role of the exchange anisotropy in the properties of Mg-warwickite. In Co-warwickite the increase of magnetocrystalline anisotropy provokes an increase in magnetic viscosity.Были получены монокристаллы MgFeBO4 и CoFeBO4 warwickites. Эффекты упорядочения зарядов и магнитные свойства были исследованы методом мессбауэровской спектроскопии. Было определено распределение катионов на М1 и M2 неэквивалентных позициях и средний заряд на металлических позициях. При низкой температуре Мессбауэровские спектры показывают поведение типа спинового стекла, с температурой замораживания спинов TSG 15.2 и 33.2 K для MG-и Co-warwickites, соответственно, более высокие, чем наблюдалось от постоянного тока и на ~ измерениях магнитной восприимчивости. Разница объясняется в терминах динамической теории подобия. Удельный форма спектров Мессбауэра в непосредственной близости от магнитного перехода на TSG показывает разницу между спин-стекольным и суперпарамагнитным поведением и демонстрирует подавляющее роль обменной анизотропии в свойствах Mg-warwickite. В Co-warwickite увеличение магнитокристаллической анизотропия провоцирует увеличение магнитной вязкости.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Antuzevics A., Rogulis U., Fedotovs A., Berzins D., Voronov V. N., Purans J.
Заглавие : EPR study of Gd3+ local structure in ScF3 crystal with negative thermal expansion coefficient
Место публикации : Phys. Scr.: IOP Publishing, 2015. - Vol. 90, Is. 11. - Ст.115801. - ISSN 0031-8949, DOI 10.1088/0031-8949/90/11/115801
Примечания : Cited References: 32. - We are grateful to Professor S Ovchinnikov for providing ScFINF3/INF samples. This work was supported by L-KC-11-0005 project Nr.KC/2.1.2.1.1/10/01/006,5.3
Предметные рубрики: ELECTRON-PARAMAGNETIC-RESONANCE
SPIN-HAMILTONIAN PARAMETERS
SINGLE-CRYSTALS
SUPERPOSITION-MODEL
CENTERS
SPECTRA
PHASE
TEMPERATURE
SIMULATION
Ключевые слова (''Своб.индексиров.''): electron paramagnetic resonance--gd3+--scf3--negative thermal expansion
Аннотация: Zero field splitting (ZFS) of Gd3+ impurity in ScF3 is studied by electron paramagnetic resonance at 77 and 295 K. ZFS parameter b4 values obtained from angular dependence simulations show that regardless of negative thermal expansion in ScF3 temperature dependence of |b4| is similar to other cubic fluoroperovskites. Our analysis of ZFS parameters indicates that the local structure of Gd3+ centres expands positively with temperature. © 2015 The Royal Swedish Academy of Sciences.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Malakhovskii A. V., Sukhachev A. L., Sokolov V. V., Gudim, I. A.
Заглавие : Giant natural circular dichroism of vibronic transitions in HoAl3(BO3)4
Место публикации : JETP Letters. - 2015. - Vol. 102, Is. 8. - P.493-495. - ISSN 00213640 (ISSN), DOI 10.1134/S0021364015200084
Примечания : Cited References: 15. - This work was supported by the Council of the President of the Russian Federation for the Support of Leading Scientific Schools (project no. NSh-2886.2014.2).
Предметные рубрики: SINGLE-CRYSTAL
OPTICAL-ABSORPTION
SPECTRA
Ho3+
IONS
PR3+
Аннотация: The giant natural optical activity of vibronic replicas of the f–f5/8 → 5F2 transition in HoAl3(BO3)4 is observed. It exceeds the optical activity related to purely electronic transitions by two orders of magnitude and corresponds to the almost complete circular polarization of the transitions. This effect is explained by the local distortions of the crystal in the excited electronic state, which lead to the mixing of electron and vibrational wavefunctions and, as a consequence, to the delocalization of the vibronic wavefunction and the enhancement of spatial dispersion, which is responsible for the optical activity.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Golovnev N. N., Molokeev M. S., Vereshchagin, Sergey N., Sterkhova I. V., Atuchin V. V.
Заглавие : The cis-trans isomer transformation, spectroscopic and thermal properties of Li, Na, K 1,3-diethyl-2-thiobarbiturate complexes
Коллективы : Ministry of Education and Science of the Russian Federation
Место публикации : Polyhedron: PERGAMON-ELSEVIER SCIENCE LTD, 2015. - Vol. 85. - P.493-498. - ISSN 0277-5387, DOI 10.1016/j.poly.2014.09.011
Примечания : Cited References:42. - The study has been carried out within the public task of the Ministry ofEducation and Science of the Russian Federation for research engineeringat the Siberian Federal University in 2014. V.V.A. is partly supportedby the Ministry of Education and Science of the Russian Federation.
Предметные рубрики: CRYSTAL-STRUCTURE
2-THIOBARBITURIC ACID
STRUCTURAL-CHARACTERIZATION
HYDROGEN-BOND
DIFFRACTION
THIOBARBITURATE
CHEMISTRY
NETWORKS
SPECTRA
SERIES
Ключевые слова (''Своб.индексиров.''): 1,3-diethyl-2-thiobarbituric acid--alkali ions--x-ray diffraction--infrared spectroscopy--thermal analysis
Аннотация: Three new complexes of 1,3-diethyl-2-thiobarbituric acid (C8H11N2O2S, HDETBA) with Li+, Na+, K+ alkali ions were synthesized. The complexes have been prepared by neutralization of 1,3-diethyl-2-thiobarbituric acid with the corresponding metal hydroxide in aqueous solution. The colorless crystals have been investigated using X-ray single crystal and powder techniques and characterized by differential scanning calorimetry, thermogravimetry and infrared spectroscopy. The compounds of MDETBA with M = Li and M = Na crystallize in the monoclinic lattice with a = 10.678(1) Å, b = 7.2687(9) Å, c = 13.202(2) Å, β = 108.841(2)°, Z = 4, V = 969.8(2) Å3, S.G. P21/n and a = 10.534(2) Å, b = 7.604(1) Å, c = 14.186(1) Å, β = 108.964(4)°, Z = 4, V = 1074.6(3) Å3, S.G. P21/n, respectively. Сompound KDETBA crystallizes in the orthorhombic lattice with a = 4.2541(6) Å, b = 14.739(2) Å, c = 16.635(3) Å, Z = 4, V = 1043.1(3) Å3, S.G. P212121. In Li(I) and Na(I) complexes, the DETBA− ion is in cis-configuration and, in the K(I) complex, this ion is in trans-configuration. The reason for the transformation from cis- to trans-configuration has been rationalized.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Slabko V. V., Tsipotan A. S. , Aleksandrovsky A. S., Slyusareva E. A.
Заглавие : Dynamics of self-organized aggregation of resonant nanoparticles in a laser field
Коллективы : Grant of the Ministry of Education and Science of the Russian Federation for Siberian Federal University; SB RAS Grant [24.31]; RFBR [14-02-00219 A]
Место публикации : Appl. Phys. B: Springer, 2014. - Vol. 117, Is. 1. - P.271-278. - ISSN 0946-2171, DOI 10.1007/s00340-014-5831-0. - ISSN 1432-0649
Примечания : Cited References: 30. - This research is partially supported by Grant of the Ministry of Education and Science of the Russian Federation for Siberian Federal University, by SB RAS Grant 24.31, and by RFBR Research Project No. 14-02-00219 A.
Предметные рубрики: PHOTOSTIMULATED AGGREGATION
SILVER
PRINCIPLES
PARTICLES
SPECTRA
SOLS
Аннотация: Self-organized aggregation of nanoparticles in external resonant laser field is considered using Brownian dynamics model. Formation probabilities are calculated for the pair of particles in dependence on laser wavelength and mutual orientation of particles. Times required for aggregation are calculated. Possibility of efficient aggregation using pulsed laser is deduced.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Platunov M. S., Varnakov S. N., Zharkov S. M., Bondarenko G. V., Weschke E., Schierle E., Ovchinnikov S. G.
Заглавие : Analysis of the structure and magnetic properties of an interface in multilayered (Fe/Si) N nanostructures with the surface-sensitive XMCD method
Коллективы : Russian Foundation for Basic Research [13-02-01265a, 14-02-31051mol-a]; Council of the President of the Russian Federation for Support of Young Scientists and Leading Scientific Schools [NSh- 2886.2014.2]; Presidium of the Russian Academy of Sciences [24.34]; Ministry of Education and Science of the Russian Federation [02.G25.31.0043]
Место публикации : JETP Letters. - 2014. - Vol. 99, Is. 12. - P.706-711. - ISSN 0021-3640, DOI 10.1134/S002136401412011X. - ISSN 1090-6487
Примечания : Cited References: 26. - We are grateful to S.V. Komogortsev for stimulating discussions and to the management of BESSY II, Helmholtz-Zentrum Berlin, for the opportunity of performing experiments at the UE46-PGM1 beamline. This work was supported by the Russian Foundation for Basic Research (project nos. 13-02-01265a and 14-02-31051mol-a), by the Council of the President of the Russian Federation for Support of Young Scientists and Leading Scientific Schools (project no. NSh- 2886.2014.2), by the Presidium of the Russian Academy of Sciences (program no. 24.34), and by the Ministry of Education and Science of the Russian Federation (state contract no. 02.G25.31.0043 and state task for research at Siberian Federal University in 2014).
Предметные рубрики: RAY CIRCULAR-DICHROISM
YIELD
SPECTRA
Fe
Аннотация: The structural and magnetic properties of (Fe/Si) N nanostructures obtained by successive deposition on the SiO2/Si(100) surface at a temperature of the substrate of 300 K have been studied. The thicknesses of all Fe and Si layers have been determined by transmission electron microscopy measurements. The magnetic properties have been studied by the X-ray magnetic circular dichroism (XMCD) method near the Fe L 3, 2 absorption edges. The orbital (m l ) and spin (m S ) contributions to the total magnetic moment of iron have been separated. The thicknesses of magnetic and nonmagnetic iron silicide on the Si/Fe and Fe/Si interfaces have been determined with the surface sensitivity of the XMCD method and the model of the interface between the nonmagnetic and weakened magnetic phases.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Myagkov V. G., Zhigalov V. S., Matsynin A. A., Bykova L. E., Mikhlin Y. L., Bondarenko G. N., Patrin G. S., Yurkin G. Yu.
Заглавие : Formation of ferromagnetic germanides by solid-state reactions in 20Ge/80Mn films
Место публикации : Thin Solid Films: Elsevier Science, 2014. - Vol. 552. - P.86-91. - ISSN 0040-6090, DOI 10.1016/j.tsf.2013.12.029
Примечания : Cited References: 53
Предметные рубрики: PHASE-FORMATION
MAGNETIC-PROPERTIES
Mn5Ge3 FILMS
X-RAY
Ge(111)
TRANSFORMATIONS
DIFFUSION
SPECTRA
SYSTEM
LAYERS
Ключевые слова (''Своб.индексиров.''): manganite-germanium--solid state reaction--first phase--mn5ge3 alloy--carbon impurity--oxygen impurity--annealing--magnetic anisotropy
Аннотация: Solid state reactions between Ge and Mn films are systematically examined using X-ray diffraction, photoelectron spectroscopy, and magnetic and electrical measurements. The films have a nominal atomic ratio Ge:Mn = 20:80 and are investigated at temperatures from 50 to 500 °C. It is established that after annealing at ~ 120°C, the ferromagnetic Mn5Ge3 phase is the first phase to form at the 20Ge/80Mn interface. As the annealing temperature increases to 300°C, the weak magnetic Mn5Ge 2 + Mn3Ge phases simultaneously begin to grow and they become dominant at 400°C. Increasing the annealing temperature to 500°C leads to the formation of the ferromagnetic phase with a Curie temperature TC ~ 350-360 K and magnetization 14-25 kA/m at room temperature. The X-ray diffraction study of the samples shows the reflections from the Mn 5Ge3 phase, and the photoelectron spectra contain the oxygen and carbon peaks. The homogeneous distribution of oxygen and carbon over the sample thickness suggests that the increased Curie temperature and magnetization are related to the migration of C and O atoms into the Mn 5Ge3 lattice and the formation of the Nowotny phase Mn5Ge3CxOy. The initiation temperature (~ 120 C) is the same in the Mn5Ge3 phase with the solid-state reactions in the Ge/Mn films as well as in the phase separation in the GexMn1 - x diluted semiconductors. Thus, we conclude that the synthesis of the Mn5Ge3 phase is the moving force for the spinodal decomposition of the GexMn 1 - x diluted semiconductors.
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