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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mironov V. L., Kerr Y. H., Kosolapova L. G., Savin I. V., Muzalevskiy K. V.
Заглавие : A temperature-dependent dielectric model for thawed and frozen organic soil at 1.4 GHz
Коллективы : Russian Science Foundation [14-17-00656]
Место публикации : IEEE J. Sel. Top. Appl. Earth Observ. Remote Sens.: IEEE-Institute Electrical and Electronics Engineers, 2015. - Vol. 8, Is. 9. - P.4470-4477. - ISSN 1939-1404, DOI 10.1109/JSTARS.2015.2442295. - ISSN 2151-1535
Примечания : Cited References:19. - This work was supported in part by a grant from the Russian Science Foundation under Project 14-17-00656
Предметные рубрики: moisture retrieval algorithm
active layer
validation
Ключевые слова (''Своб.индексиров.''): dielectric constant--dielectric losses--dielectric measurement--l-band--modeling--soil moisture--soil properties
Аннотация: A single-frequency dielectric model for thawed and frozen Arctic organic-rich (80%-90% organic matter) soil was developed. The model is based on soil dielectric data that were measured over the ranges of volumetric moisture from 0.007 to 0.573 cm3/cm3, dry soil density from 0.564 to 0.666 g/cm3, and temperature from 25°C to -30°C (cooling run), at the frequency of 1.4 GHz. The refractive mixing model was applied to fit the measurements of the soil's complex refractive index (CRI) as a function of soil moisture, with the values of temperature being fixed. Using the results of this fitting, the parameters of the refractive mixing model were derived as a function of temperature. These parameters involve the CRIs of soil solids as well as bound, transient, and free soil water components. The error of the dielectric model was evaluated by correlating the predicted complex relative permittivity (CRP) values of the soil samples with the measured ones. The coefficient of determination (R2) and the root-mean-square error (RMSE) were estimated to be R2 = 0.999, RMSE = 0.27 and R2 = 0.993, RMSE = 0.18 for the real and imaginary parts of the CRP, respectively. These values are in the order of the dielectric measurement error itself. The proposed dielectric model can be applied in active and passive remote-sensing techniques used in the areas with organicrich soil covers, mainly for the SMOS, SMAP, and Aquarius missions.
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Вид документа : Статья из сборника (выпуск продолж. издания)
Шифр издания :
Автор(ы) : leskova J., Muzalevskiy K. V., Ruzicka Z.
Заглавие : Arctic lakes thickness measurement in the Lena river delta based on the Sentinel-1 observations
Коллективы : Regional Problems of Earth Remote Sensing, "Региональные проблемы дистанционного зондирования Земли", международная конференция, Сибирский федеральный университет
Место публикации : E3S Web Conf. - 2021. - Vol. 333: Regional Problems of Earth Remote Sensing (RPERS 2021). - Ст.01007. - , DOI 10.1051/e3sconf/202133301007
Примечания : Cited References: 5
Аннотация: In this paper, we investigate the possibilities of ice thickness remote sensing on freshwater lakes based on Sentinel-1 observations. Fr. was selected as a test site. Kurungnakh Island, located in the Lena River delta, was selected as a test site, where 10 lakes with floating and grounded ice were selected. For the test lakes, the time series of backscatting coefficients measured by Sentinel-1 at horizontal-horizontal polarization (EW mode) and at an angle of 18-20 from September 2015 to June 2017 were analyzed. The average lakes ice thickness was estimated based on the Lebedev’s model and air temperature according to the European Center for Medium-Range Weather Forecasts (ECMWF ERA5). It is shown that, the dependence between backscattering coefficient and ice thickness (120-140 cm) can be described a linear function (with a standard deviation of 13.5-25.3 cm and a determination coefficient of 0.70-0.79). The preliminary studies shows that the Sentinel-1 radar data is promising for remote sensing of ice thickness on freshwater arctic lakes.
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Вид документа : Статья из сборника (выпуск продолж. издания)
Шифр издания :
Автор(ы) : Burmitskikh A. V., Boev N. M., Izotov A. V., Andyuseva V. G.
Заглавие : Automated measuring unit for analysis of thin magnetic film ferroresonance spectrum
Коллективы : International Siberian Conference on Control and Communications
Место публикации : International Siberian Conference on Control and Communications, SIBCON 2019: Proceedings: IEEE, 2019. - Ст.8729594. - , DOI 10.1109/SIBCON.2019.8729594
Примечания : Cited References: 6
Аннотация: This paper considers hardware and software for automated analysis of thin magnetic film ferroresonance spectrum to determine the rate of growth and decrease in ferroresonance spectrum (conversion factor parameter). The measuring element of automated system is the strip line which is short-circuited. The measuring unit is used to study Ni 80 Fe 20 permalloy films, with thickness of more than 300 Å. Conversion factor, magnetic permeability μ, uniaxial magnetic anisotropy, ferromagnetic spectrum resonance line width, saturation magnetization are analyzed from 50 MHz to 2 GHz frequency range. The magnetic films are used to design frequency selective filters, phase shifters and weak-field magnetic sensors. The thin magnetic film sensors are high sensitive magnetometers, with wide frequency range, low dimensions and weight [1]. © 2019 IEEE.
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Вид документа : Статья из сборника (выпуск продолж. издания)
Шифр издания :
Автор(ы) : Muzalevskiy K. V., Mikhaylov M. I., Ruzicka Z.
Заглавие : Calibration of UWB UAV radar for the remote measurement of reflection coefficient
Коллективы : IEEE Ural-Siberian Conference on Biomedical Engineering, Radioelectronics and Information Technology
Место публикации : IEEE Ural-Siberian Conference on Biomedical Engineering, Radioelectronics and Information Technology (USBEREIT). - 2023. - P.105-108. - , DOI 10.1109/USBEREIT58508.2023.10158870
Примечания : Cited References: 16. - The investigation supported by the Russian Science Foundation and the Krasnoyarsk Regional Science Foundation, project № 22-17-20042
Аннотация: In this work, the possibility of the remote measurement of reflection coefficient in the ultra-wide frequency range from 425 MHz to 1010 MHz from the board of unmanned aerial vehicle (UAV) using ultra-wide band (UWB) radar was investigated. With this in mind, the antenna-feeder path of UAV UWB radar is calibrated. The calibration process consisted in measuring the reflection coefficient from the brass mesh sheet at various UAV hovering heights. Printed log-periodic dipole antenna was used as transmitter-receiver antenna. As a result, the antenna return loss in an empty-room and the complex antenna response function of the antenna-feeder path of the UAV UWB radar were found. It is shown that the amplitude of the reflected wave from a brass mesh sheet can be measured with root-mean square error (RMSE), RMSE=0.017 1/m and a determination coefficient (R 2 ) of R 2 = 0.967. Therewith the UAV hovering heights measured by the pulse method and the on-board laser rangefinder correlates with each other with R2=0.999 and with RMSE=3.5cm (distance measurement error of the laser rangefinder is ±1cm, surface irregularities of the brass mesh sheet were no more than 1.5cm). Measured in the frequency range from 500 MHz to 900 MHz, the reflection coefficient from fresh lake water by UAV UWB radar with a relative error of no more than 7.5% (practically does not depend on the height of the UAV hovering, approximately from 2.2 m to 5.2 m) coincides with the calculated one by the Stogryn's formulas.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mamalis A. G., Ovchinnikov S. G., Petrov M. I., Balaev D. A., Shaihutdinov K. A., Gohfeld D. M., Kharlamova S. A., Vottea I. N.
Заглавие : Composite materials on high-T-c superconductors and BaPbO3, Ag basis
Коллективы : International Conference on New Theories, Discoveries and Applications of Superconductors and Related Materials
Разночтения заглавия :авие SCOPUS: Composite materials on high-Tc superconductors and BaPbO3, Ag basis
Место публикации : Physica C. - 2001. - Vol. 364. - P.174-177. - ISSN 0921-4534, DOI 10.1016/S0921-4534(01)00749-3
Примечания : Cited References: 9
Ключевые слова (''Своб.индексиров.''): composite high-t-c superconductors--superconducting fault current limiter--composite high-tc superconductors--superconducting fault current limiter--composite materials--electric fault currents--interfaces (materials)--magnetic variables measurement--mathematical models--scanning electron microscopy--spectrometry--superconducting transition temperature--superconductivity--x ray diffraction analysis--solid state reactions--high temperature superconductors
Аннотация: The preparation., processing and characterization of the composite materials on high-T-c superconductor (HTSC) basis, YBa2Cu3O7/Ag and Y0.75Lu0.25Ba2Cu3O7/BaPbO3, is reported. The initial components YBa2Cu3O7 and BaPbO3 were prepared by the standard solid state reaction technique. The microstructures of the samples were observed by scanning electron microscopy. whilst the XRD paterns of the composites HTSC+Ag and HTSC+BaPbO3 revealed the 123 superconducting phase and the Ag or BaPbO3 structure. The chemical compositions of the powders and the interface zone were found by employing energy dispersive spectrometry. The resistive and magnetic measurements of the composites indicated the transition temperature 93.5 K. Application of such composite materials in the construction of a superconducting fault current limiter model is reported. (C) 2001 Elsevier Science B.V. All rights reserved.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S., Ryabinkina L. I., Abramova G. M., Romanova O. B., Vorotynov A. M., Velikanov D. A., Kiselev N. I., Balaev A. D.
Заглавие : Conductivity, weak ferromagnetism, and charge instability in an alpha-MnS single crystal
Разночтения заглавия :авие SCOPUS: Conductivity, weak ferromagnetism, and charge instability in an α-MnS single crystal; авие SCOPUS: Conductivity, weak ferromagnetism, and charge instability in an ?-MnS single crystal
Место публикации : Phys. Rev. B: AMERICAN PHYSICAL SOC, 2005. - Vol. 71, Is. 12. - Ст.125204. - ISSN 1098-0121, DOI 10.1103/PhysRevB.71.125204; Phys. Rev. B Condens. Matter Mater. Phys. - 2005. - Vol. 71, Is. 12. - Ст.125204. - Вариант Sopus
Примечания : Cited References: 11
Предметные рубрики: MANGANITES
Ключевые слова (''Своб.индексиров.''): ferromagnetic material--manganese derivative--absorption spectroscopy--article--calculation--conductance--crystal--electron spin resonance--hybridization--magnetic field--magnetism--measurement--molecular interaction--temperature dependence--temperature measurement--ferromagnetic material--manganese derivative--absorption spectroscopy--article--calculation--conductance--crystal--electron spin resonance--hybridization--magnetic field--magnetism--measurement--molecular interaction--temperature dependence--temperature measurement
Аннотация: The temperature dependence of resistivity, magnetization, and electron-spin resonance of the α-MnS single crystal were measured in temperature range of 5 K T 550 K. Magnetization hysteresis in an applied magnetic field up to 0.7 T at T
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Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Chistyakov N. S., Tuschkov B. P.
Заглавие : Constituents measurement of complex superhighfrequency susceptibility of magnetic films
Коллективы : Академия наук СССР, Научный совет по комплексной проблеме "Физика твердого тела" АН СССР, Институт физики им. Л.В. Киренского Сибирского отделения РАН, Иркутский государственный педагогический институт, International colloquium on physics of magnetic films, Международный коллоквиум по физике магнитных пленок
Место публикации : International colloquium on physics of magnetic films: [program and abstracts]/ chairman L. V. Kirensky ; vice-chaiman: V. A. Buravikhin, R. V. Telesnin ; progr. and publ. com. N. M. Salansky ; progr. com.: V. A. Ignatchenko, Yu. V. Zakharov [et al]. - Irkutsk, 1968. - Section Ferromagnetic resonance, spin-wave resonance, high-frequency properties. - Ст.6-A.1. - P.59 (Шифр В37/H99-248389966)
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Orlov Yu. S.
Заглавие : Covalence-induced stabilization of an intermediate-spin state and the magnetic susceptibility of LaCoO3
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2007. - Vol. 104, Is. 3. - P436-444. - ISSN 1063-7761, DOI 10.1134/S1063776107030090
Примечания : Cited References: 24. - This work was supported by the program of the Division of Physical Sciences of the Russian Academy of Sciences “Strong Electronic Correlations,” the integration project SORAN-URORAN (grant no. 74), and the Krasnoyarsk krai Science Foundation
Предметные рубрики: TRANSITION
Ключевые слова (''Своб.индексиров.''): band structure--electron transitions--ground state--hamiltonians--magnetic susceptibility--magnetic variables measurement--spin dynamics--covalence induced stabilization--diagnoalization--orbital degeneracy--spin states--lanthanum compounds
Аннотация: The energies of terms with spins S = 0, 1, 2 have been found using exact diagonalization of the multielectron Hamlitonian of a multiband pd model for the CoO6 cluster. Co (e(g) orbital)-O hops, which form the covalent sigma bond, are shown to decrease the energy of the state (IS) with an intermediate spin (S = 1) as compared to the energy of the state (LS) with a low spin (S = 0). An analogue of the Tanabe-Sugano diagram that takes into account the covalence of the CoO6 cluster is constructed. The state with S = 1 is shown to be a ground state at certain model parameters. An increase in temperature is established to decrease the crystal field and, thus, favors the transition of the ground state from LS to IS at T = 100 K and the transition of the IS ground state to a state (HS) with a high spin (S = 2) at T = 550 K. The magnetic susceptibility of LaCoO3 is calculated with allowance for the LS, IS, and HS states and for the fact that the HS state exhibits threefold orbital degeneracy of the t(2g) shell, which results in an effective orbital moment L = 1 and the importance of spin-orbit interaction. The behavior of this magnetic susceptibility agrees well with the experimental chi(T) dependence of LaCoO3.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sadreev A. F., Bulgakov E. N., Pilipchuk A. S., Miroshnichenko A., Huang L.
Заглавие : Degenerate bound states in the continuum in square and triangular open acoustic resonators
Место публикации : Phys. Rev. B. - 2022. - Vol. 106, Is. 8. - Ст.085404. - ISSN 24699950 (ISSN), DOI 10.1103/PhysRevB.106.085404
Примечания : Cited References: 43
Аннотация: We consider square and equilateral triangular open acoustic resonators with the C4v and C3v symmetries, respectively. There is a unique property of square and triangular resonators of accidental number fourfold degeneracy of eigenstates that gives rise to twofold-degenerate Friedrich-Wintgen (FW) bound states in the continuum (BICs). Compared to usual FW BICs, the degenerate FW BICs maintain high Q factor in wide range of the size of resonators. That removes the fabrication difficulties of the proper choice of resonator. The presence of degenerate BICs in triangular resonators is extremely sensitive to switch output flows by small perturbations with 100% efficiency.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bulgakov E. N., Pilipchuk A. S., Sadreev A. F.
Заглавие : Desktop laboratory of bound states in the continuum in metallic waveguide with dielectric cavities
Место публикации : Phys. Rev. B. - 2022. - Vol. 106, Is. 7. - Ст.075304. - ISSN 24699950 (ISSN), DOI 10.1103/PhysRevB.106.075304
Примечания : Cited References: 64. - We are grateful to Lujun Huang, Andrey Miroshnichenko and Yi Xu for presentation of unpublished paper and discussions. The research was supported by Russian Science Foundation No. 22-12-00070
Аннотация: We consider dielectric cavities whose radiation space is restricted by two parallel metallic planes. The TM solutions of the Maxwell equations of the system are equivalent to the solutions of periodical arrays of dielectric cavities. The system readily allows to achieve bound states in the continuum (BICs) of any type including topological BICs as dependent on position and orientation of the cavities relative to the planes and that extremely facilitates experimental studies in comparison to infinite arrays of the cavities. We show the effect of merging of topologically protected BICs that pushes the square asymptotic of the Q factor into the power degree 4 or even 6.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aleksandrovsky A. S., Vyunishev A. M., Zaitsev A. I., Pospelov G. I., Slabko V. V.
Заглавие : Diagnostics of fs pulses by noncollinear random quasi-phase-matched frequency doubling
Место публикации : Appl. Phys. Lett. - 2011. - Vol. 99, Is. 21. - Ст.211105. - ISSN 0003-6951, DOI 10.1063/1.3664094
Примечания : Cited References: 12. - The work was supported by Ministry of Education and Science of Russian Federation (Contract No. 16.740.11.0150); Grant of President of Russian Federation for support of leading scientific schools Grant Nos. SS-4645.2010.2 and RNP.2.1.1.3455 and Projects Nos. 2.5.2 and 3.9.1 of PSB RAS and 27.1 and 5 of SB RAS. A. M. Vyunishev is grateful for the support from Krasnoyarsk Regional Fund of Science and Technical Activity Support.
Ключевые слова (''Своб.индексиров.''): autocorrelation measurement--cross-correlation measurements--fs pulse--noncollinear--nonlinear photonic crystals--nonuniformity--quasi-phase-matched frequency doubling--random structures--tetraborate--vacuum ultraviolets--wide spectral range--band structure--frequency doublers--strontium--photonic crystals
Аннотация: Noncollinear random quasi-phase-matched frequency doubling in nonlinear photonic crystal (NPC) of strontium tetraborate (SBO) can be used for background-free autocorrelation measurements of ultrashort pulses in wide spectral range without any angular tuning of nonlinear photonic crystal. Nonuniformity of reciprocal superlattice vectors spectrum of random structure does not affect the accuracy of measurement. Nonlinear photonic crystals of strontium tetraborate are attractive medium for cross-correlation measurements in deep and vacuum ultraviolet. VC 2011 American Institute of Physics. [doi:10.1063/1.3664094]
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gao H., Molokeev M. S., Chen Q., Yang X., Wang X., Ma B.
Заглавие : Effect of ligand environment of rare-earth ions on temperature measurement performance of SrAO4:xEu3+ (A = Mo and W) phosphors
Место публикации : Ceram. Int. - 2022. - Vol. 48, Is. 24. - P.36835-36844. - ISSN 02728842 (ISSN), DOI 10.1016/j.ceramint.2022.08.247
Примечания : Cited References: 58. - This work was supported by the National Natural Science Foundation of China (Grant No. 51802172) and the Natural Science Foundation of Qinghai Province (Grant No. 2021-ZJ-713)
Аннотация: Molybdate and tungstate with scheelite-type structure are excellent self-luminescent materials, which can be used as ideal hosts for the doping of rare-earth ions. In this study, a series of Eu3+-activated SrAO4 (A = Mo and W) phosphors were successfully synthesized, and their crystal structures, photoluminescence properties, and temperature measurement performance were analyzed in detail. These phosphors were excited by UV light (291 nm and 247 nm, respectively), with clear energy transfer (ET) (MoO42−→Eu3+ or WO42−→Eu3+). According to fluorescence intensity ratio (FIR) and Judd–Ofelt (J–O) theory, compared to SrWO4:0.01Eu3+ phosphor, SrMoO4:0.01Eu3+ phosphor exhibited better thermal stability, with relatively low Sa value (maximum values were 5.082 %K−1 and 20.74 %K−1, respectively), and their Sr values were not significantly different (maximum values were 0.864 %K−1 and 0.83 %K−1, respectively). Sa value was negatively correlated to central asymmetry of Eu3+, but the optimal Sr value tended to be more suitable for central asymmetry of Eu3+. In addition, Eu3+ exhibited stronger central asymmetry as well as covalency of Eu–O bond in SrMoO4. Results reveal that SrMoO4:xEu3+ and SrWO4:xEu3+ can be used for luminescent thermometers.
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13.

Вид документа : Статья из журнала
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Автор(ы) : Ovchinnikov S. G., Korshunov M. M., Shneyder E. I.
Заглавие : Effect of short antiferromagnetic correlations on the normal and superconducting properties in copper oxides
Место публикации : Diffusion and Defect Data Pt.B: Solid State Phenomena: Trans Tech Publications Ltd, 2011. - Vol. 168-169. - С. 561-566. - ISSN 10120394 (ISSN); 9783037850213 (ISBN), DOI 10.4028/www.scientific.net/SSP.168-169.561
Ключевые слова (''Своб.индексиров.''): high temperature superconductivity--short range antiferromagnetic order--strong electron correlations--antiferromagnetic materials--antiferromagnetism--copper oxides--electron correlations--electron density measurement--antiferromagnetism--electron correlations--ab initio--antiferromagnetic correlations--cuprates--high-t--high-temperature superconductivity--hubbard--low energies--multiband model--short range antiferromagnetic order--strong electron correlations--superconducting properties--t-j models--antiferromagnetic orderings--superconductivity--copper oxides--high temperature superconductivity
Аннотация: The abnormal "normal" state and origin of high temperature superconductivity in cuprates are still not clear [1-2]. The strong electron correlations (SEC) are known to be one of the main difficulties for the theory of high- Tc cuprates. The conventional LDA (local density approximation) approach to the band structure fails in the regime of SEC. Various realistic multiband models of a CuO2 layer at low energy result in the effective Hubbard or t - J models [3-7]. The hybrid LDA+GTB scheme [8] generates the low-energy effective t - t? - t? - J* model with all parameters calculated ab initio.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gavrichkov V. A., Ovchinnikov S. G., Nekrasov I. A., Pchelkina Z. V.
Заглавие : Electronic Structure of p-Type La1-xMx2+MnO3 Manganites in the Ferromagnetic and Paramagnetic Phases in the LDA plus GTB Approach
Разночтения заглавия :авие SCOPUS: Electronic structure of p-Type La 1-x M x 2+ MnO 3 manganites in the ferromagnetic and paramagnetic phases in the LDA + GTB approach
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2011. - Vol. 112, Is. 5. - P860-876. - ISSN 1063-7761, DOI 10.1134/S1063776111030101
Примечания : Cited References: 47. - This study was supported financially by integration project no. 40 of the Ural and Siberian Branches of the Russian Academy of Sciences, the program "Strong Electron Correlations" of the Russian Academy of Sciences, and the Russian Foundation for Basic Research (project no. 10-02-00251-a).
Предметные рубрики: DOUBLE-EXCHANGE
COLOSSAL MAGNETORESISTANCE
THIN-FILMS
PHYSICS
LA1-XSRXMNO3
RESISTIVITY
SEPARATION
TRANSPORT
MODEL
Ключевые слова (''Своб.индексиров.''): complex structure--cubic materials--ferromagnetic phase--half metals--jahn teller effect--metal properties--metal types--orbitals--p-type--paramagnetic phase--paramagnetic phasis--quasi particles--spectral intensity--spin projections--strong electron correlations--barium--density functional theory--electron correlations--electron density measurement--electronic properties--electronic structure--fermi level--ferromagnetic materials--ferromagnetism--manganese oxide--manganites--paramagnetic materials--paramagnetism--valence bands--lanthanum
Аннотация: The band structure, spectral intensity, and position of the Fermi level in doped p-type La1-xMx2+ MnO3 manganites (M = Sr, Ca, Ba) is analyzed using the LDA + GBT method for calculating the electronic structure of systems with strong electron correlations, taking into account antiferro-orbital ordering and using the Kugel-Khomskii ideas and real spin S = 2. The results of the ferromagnetic phase reproduce the state of a spin half-metal with 100% spin polarization at T = 0, when the spectrum is of the metal type for a quasiparticle with one spin projection and of the dielectric type for the other. It is found that the valence band becomes approximately three times narrower upon a transition to the paramagnetic phase. For the paramagnetic phase, metal properties are observed because the Fermi level is located in the valence band for any nonzero x. The dielectrization effect at the Curie temperature is possible and must be accompanied by filling of d(x) orbitals upon doping. The effect itself is associated with strong electron correlations, and a complex structure of the top of the valence band is due to the Jahn-Teller effect in cubic materials. DOI: 10.1134/S1063776111030101
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Orlov Y. S., Nekrasov I. A., Pchelkina Z. V.
Заглавие : Electronic structure, magnetic properties, and mechanism of the insulator-metal transition in LaCoO3 taking into account strong electron correlations
Разночтения заглавия :авие SCOPUS: Electronic structure, magnetic properties, and mechanism of the insulator-metal transition in LaCoO 3 taking into account strong electron correlations
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2011. - Vol. 112, Is. 1. - P140-151. - ISSN 1063-7761, DOI 10.1134/S1063776110061159
Примечания : Cited References: 36. - This study was supported financially by the Siberian and Ural Branches of the Russian Academy of Sciences (Integration Project no. 40), Department of Physics of the Russian Academy of Sciences (Program 2.3), Russian Foundation for Basic Research (Project nos. 09-02-00171-a and 10-02-00251), and Noncommercial "Dynasty" Foundation.
Предметные рубрики: SPIN-STATE TRANSITION
CHARGE
Ключевые слова (''Своб.индексиров.''): energy spectra--excited energy level--finite temperatures--gap state--gap widths--high temperature--high-temperature anomalies--insulator metal transition--pauli contribution--spin crossovers--strong electron correlations--temperature dependence--total magnetization--cobalt compounds--density functional theory--electron correlations--electron density measurement--electronic properties--electronic structure--magnetic susceptibility--semiconductor insulator boundaries--spectroscopy--metal insulator transition
Аннотация: The electronic structure of LaCoO3 at finite temperatures is calculated using the LDA+GTB method taking into account strong electron correlations and possible spin crossover upon an increase in temperature. Gap states revealed in the energy spectrum of LaCoO3 reduce the dielectric gap width upon heating; this allowed us to describe the insulator-metal transition observed in this compound at T = 500-600 K. The temperature dependence of the magnetic susceptibility with a peak at T a parts per thousand 100 K is explained by the Curie contribution from thermally excited energy levels of the Co3+ ion. At high temperatures, the Pauli contribution from a band electron is added and the total magnetization of LaCoO3 is considered as the sum M (tot) = M (loc) + M (band). The second term describes the band contribution appearing as a result of the insulator-metal transition and facilitating the emergence of a high-temperature anomaly in the magnetic susceptibility of LaCoO3.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Denisova E. A., Iskhakov R. S., Stolyar S. V., Komogortsev S. V., Chekanova L. A., Maltsev V. K., Kalinin Y. E., Sitnikov A. V.
Заглавие : Exchange interaction in the Co-SiO2 nanocomposite films
Место публикации : TRENDS IN MAGNETISM. - 2011. - Vol. 168-169. - С. 265-268. - ISSN 10120394 (ISSN); 9783037850213 (ISBN), DOI 10.4028/www.scientific.net/SSP.168-169.265
Ключевые слова (''Своб.индексиров.''): exchange coupling parameter--ferromagnetic resonance--granular composite films--cobalt--exchange coupling--exchange interactions--ferromagnetic materials--ferromagnetic resonance--ferromagnetism--magnetic resonance measurement--nanocomposite films--nanocomposites--nuclear magnetic resonance--resonance--silicon compounds--spin waves--cobalt--exchange coupling--exchange interactions--ferromagnetic materials--ferromagnetic resonance--ferromagnetism--magnetic resonance measurement--magnetism--nanocomposite films--nuclear magnetic resonance--spin fluctuations--spin waves--co content--coupling parameters--dispersion relations--granular composite films--magnetic measurements--nanogranulars--nmr studies--structural state--granular composites--nano-granular--standing spin waves--composite films--composite films
Аннотация: The properties of Co-SiO2 nanogranular composite films, containing a Co volume fraction ranging from 0.3 to 0.8, have been characterized by means of magnetic measurements, NMR study, and ferromagnetic resonance. Thermal decrease of CoX(SiO2)100-X magnetization follows the T3/2 law and allows to estimate the exchange interaction constant A. With growing nominal Co content the transitions from granular to continuous structural state at 36% Co are registered by FMR measurements. The spectrum of standing spin-wave has been detected in the perpendicular experiment configuration for films with the Co content above 52 vol. %. It is found that the type of the dispersion relation of spin waves in Co-SiO2 composite films is affected by the exchange coupling fluctuations.
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17.

Вид документа : Статья из журнала
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Автор(ы) : Mironov V. L., Kosolapova L. G., Fomin S. V., Savin I. V.
Заглавие : Experimental analysis and empirical model of the complex permittivity of five organic soils at 1.4 GHz in the temperature range from −30 °C to 25 °C
Место публикации : IEEE Trans. Geosci. Remote Sensing. - 2019. - Vol. 51, Is. 6. - P.3778 - 3787. - ISSN 0196-2892, DOI 10.1109/TGRS.2018.2887117
Примечания : Cited References: 26. - This work was supported by the Russian Foundation for Basic Research under Grant 16-05-00572.
Аннотация: The dielectric measurements were made for five organic soils taken from the tundra territories of Alaska, Yamal, and Taimyr, with the content of organic matter varying from 35% to 80%. The measurements were carried out in the temperature range from −30 °C to 25 °C, frequencies from 0.45 to 16 GHz and soil moisture from close to zero to the field moisture capacity. The refractive mixing model was applied to fit the measurements of the soil’s complex refractive index (CRI) as a function of soil moisture, with the values of temperature being fixed. As a result, a respective dielectric model was developed. The amounts of bound and transient water in the thawed and frozen soils were introduced as parameters of the developed model and derived as a function of temperature and content of soil organic matter. The other parameters which concern the CRIs of soil solids as well as bound, transient, and liquid soil water or ice components were derived as a function of temperature. The errors of the proposed model estimated in terms of the values of normalized root-mean-sqaure error for the real and imaginary parts of the soil complex relative permittivity appeared to be 6%–7% and 23%, respectively. The proposed dielectric model can be applied in active and passive remote sensing, in particular, for the SMOS, SMAP, and Aquarius missions after testing in ground-based experiments.
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18.

Вид документа : Статья из журнала
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Автор(ы) : Kliava J., Edelman I. S., Ivanova O. S., Ivantsov R. D., Bayukov O. A., Petrakovskaja E. A., Zaikovskiy V., Bruckental I., Yeshurun Y., Stepanov S.
Заглавие : Formation and evolution of magnetic nanoparticles in borate glass simultaneously doped with Fe and Mn oxides
Коллективы :
Место публикации : J. Appl. Phys.: AMER INST PHYSICS, 2008. - Vol. 104, Is. 10. - Ст.103917. - ISSN 0021-8979, DOI 10.1063/1.3021289
Примечания : Cited References: 37. - A financial support from the Russian Foundation for Basic Research (RFBR)-CNRS (Grant No. 07-02-92174) is highly appreciated. R. Ivantsov is grateful to the Russian Science Support Foundation. Y. Yeshurun acknowledges the support of the Israel Scienc Foundation (ISF).
Предметные рубрики: COBALT FERRITE PARTICLES
SUPERPARAMAGNETIC RESONANCE
GAMMA-FE2O3 NANOPARTICLES
MATRIX
SIZE
SYSTEMS
Ключевые слова (''Своб.индексиров.''): aluminium compounds--borate glasses--coercive force--faraday effect--heat treatment--iron compounds--magnetic hysteresis--magnetic particles--magnetic susceptibility--manganese compounds--mossbauer effect--nanoparticles--paramagnetic materials--potassium compounds--remanence--superparamagnetism--transmission electron microscopy--x-ray chemical analysis--atomic spectroscopy--auger electron spectroscopy--crystal structure--electric relays--electronic medical equipment--ferrite--ferrites--glass--heat treatment--hysteresis--hysteresis loops--magnetic properties--magnetic resonance measurement--magnetic susceptibility--magnetism--manganese--manganese compounds--molybdenum--nanoparticles--optical properties--ozone water treatment--polydispersity--superparamagnetism--borate glasses--concentration ratios--electron magnetic resonances--emr spectrums--experimental techniques--faraday rotations--glass compositions--glass matrixes--glass preparations--magnetic measurements--magnetic nano particles--magnetic orders--magnetically ordered systems--magneto-optical properties--manganese ferrites--mean diameters--mn oxides--phase states--polydisperse nanoparticles--remnant magnetizations--ssbauer spectroscopies--superparamagnetic--superparamagnetic states--thermal treatments--variable temperatures--magnetic materials
Аннотация: Evolution of the phase state of paramagnetic additions at various stages of synthesis and subsequent thermal treatment of glasses of the system Al(2)O(3)-K(2)O-B(2)O(3) simultaneously doped with Fe(2)O(3) and MnO is studied by means of a combination of experimental techniques: Faraday rotation (FR), electron magnetic resonance (EMR), transmission electron microscopy (TEM), Mossbauer spectroscopy, and magnetic measurements. Both FR and EMR show that magnetically ordered clusters occur already at the first stage of the glass preparation. In particular, for the ratio of the Fe and Mn oxides in the charge close to 3:2, fine magnetic nanoparticles are formed with characteristics similar to those of manganese ferrite. By computer simulating the EMR spectra at variable temperatures, a superparamagnetic nature of these nanoparticles is confirmed and their mean diameter is estimated as approximately 3.2 nm. In the thermally treated glasses larger magnetic nanoparticles are formed, giving rise to FR spectra, characteristic of magnetically ordered systems, and the EMR spectra different from those in as-prepared glasses but also showing superparamagnetic narrowing. The Mossbauer spectroscopy corroborates the manganese ferrite structure of the nanoparticles and indicates their coexistence in the ferrimagnetic and superparamagnetic states. The TEM shows the presence of polydisperse nanoparticles on the background of the glass matrix, and electron diffraction of a selected region containing larger particles indicates a crystal structure close to that of MnFe(2)O(4). Energy-dispersive atomic x-ray spectra confirm that the major part of Fe and Mn introduced to the glass composition is gathered in the particles, with the concentration ratio close to 2:1, characteristic of bulk MnFe(2)O(4). Magnetic hysteresis loops of samples subjected to an additional thermal treatment demonstrate a strong increase in the coercive force, remnant magnetization, and high-field magnetic susceptibility with temperature decrease. The consistent results obtained using various techniques demonstrate that the formation of nanoparticles with characteristics close to those of MnFe(2)O(4) confers to these glasses magnetic and magneto-optical properties typical of substances possessing magnetic order.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Shneyder E. I., Korshunov M. M.
Заглавие : From underdoped to overdoped cuprates: two quantum phase transitions
Разночтения заглавия :авие SCOPUS: From underdoped to overdoped cuprates: Two quantum phase transitions
Место публикации : J. Phys.: Condens. Matter: IOP PUBLISHING LTD, 2011. - Vol. 23, Is. 4. - Ст.45701. - ISSN 0953-8984, DOI 10.1088/0953-8984/23/4/045701
Примечания : Cited References: 58. - We would like to thank S Sakai for useful discussions. The authors acknowledge support by the Russian Foundation for Basic Research (grant N 09-02-00127), by the Integration Program of SBRAS N40, the Presidium RAS Program 5.7, President of Russia (grant MK-1683.2010.2), FCP Scientific and Research-and-Educational Personnel of Innovative Russia for 2009-2013 (GK P891), and in part by the National Science Foundation under grant NSF PHY05-51164.
Предметные рубрики: HIGH-TEMPERATURE SUPERCONDUCTORS
T-J MODEL
CORRELATED FERMION SYSTEMS
VALENCE BOND STATE
MEAN-FIELD-THEORY
CRITICAL-POINT
HEISENBERG-ANTIFERROMAGNET
EXCITATIONS
PSEUDOGAP
OSCILLATIONS
Ключевые слова (''Своб.индексиров.''): critical concentration--critical points--cuprates--density of state--fermi surface topology--hall effect measurement--high-t--optimal doping--overdoped--pseudo-gap--quantum phase transitions--theoretical study--copper compounds--hall effect--magnetic field effects--phase diagrams--phase transitions
Аннотация: Several experimental and theoretical studies indicate the existence of a critical point separating the underdoped and overdoped regions of the high-T-c cuprates' phase diagram. There are at least two distinct proposals on the critical concentration and its physical origin. The first one is associated with the pseudogap formation for p p*, with p* approximate to 0.2. The other relies on the Hall effect measurements and suggests that the critical point and the quantum phase transition (QPT) take place at optimal doping, p(opt) approximate to 0.16. Here we have performed a precise density of states calculation and found that there are two QPTs and the corresponding critical concentrations associated with the change of the Fermi surface topology upon doping.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Trabs P., Noack F., Aleksandrovsky A. S., Zaitsev A. I., Petrov V.
Заглавие : Generation of coherent vacuum UV radiation in randomly quasi-phase-matched strontium tetraborate
Коллективы : Conference on Lasers and Electro-Optics
Место публикации : Conference on Lasers and Electro-Optics Europe - Technical Digest: IEEE-Institute Electrical and Electronics Engineers, 2015. - Vol. 2015-August. - ISSN 9781557529688 (ISBN)
Ключевые слова (''Своб.индексиров.''): crystals--frequency conversion--harmonic analysis--nonlinear optics--optical harmonic generation--optical pulses--wavelength measurement
Аннотация: Tunable coherent radiation is generated in the VUV down to 121 nm using random quasi-phase-matching in strontium tetraborate, the shortest wavelength ever produced with a second-order nonlinear optical process in a solid-state material. © 2015 OSA.
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