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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Удод, Любовь Викторовна, Ситников, Максим Николаевич
Заглавие : Влияние катионного замещения на полиморфные переходы в пирасаннате висмута Bi2Sn2O7
Место публикации : Вестник СибГАУ. - Красноярск: СибГАУ, 2015. - Т. 16, № 4. - С. 975-982. - ISSN 1816-9724
Примечания : Библиогр.: 53. - Работа выполнена при финансовой поддержке Российского фонда фундаментальных исследований, грант № 15-42-04099 р_сибирь_а, и государственного задания № 114090470016
Ключевые слова (''Своб.индексиров.''): полиморфные переходы--диэлектрическая проницаемость--электросопротивление--катионное замещение--дифференциальная сканирующая калориметрия--polymorphic transitions--dielectric permeability--cation substitution--electrical resistivity--differential scanning calorimetry
Аннотация: Рассмотрена разработка технологии новых сенсорных материалов, необходимых для газочувствительных приборов, применяемых в ракетостроении. Целью данной работы является изучение влияния допирования разновалентными катионами на кристаллографическую структуру, диэлектрические и электрические свойства пирохлорного соединения Bi 2Sn 2O 7, обладающего селективной избирательностью к газам. Методом твердофазного синтеза впервые синтезированы соединения Bi2(Sn1-xMex)2O7, где Me = Mn, Cr, x = 0, 0,05, находящиеся сразу в двух полиморфных модификациях - орторомбической и кубической. В твердых растворах Bi2(Sn0,95Cr0,05)2O 7 методом сканирующей калориметрии обнаружено два новых структурных перехода, по сравнению со станнатом висмута Bi2Sn2O7. Ионы Mn 4+ сместили фазовые границы полиморфных переходов в сторону меньших температур, а фазовый α→β-переход около 370 К, характерный для Bi2(Sn1-xCrx)2O7, где x = 0, 0,05, подавили почти полностью. Полиморфный переход при Т = 543 К для Bi 2(Sn0,95Mn0,05) 2O 7 протекает с выделением тепла, в отличие от Bi2(Sn1-xCrx)2O7, где x = 0, 0,05. Исследована взаимосвязь структурных, электрических и диэлектрических свойств. Установлены аномалии в температурной зависимости электросопротивления и диэлектрической проницаемости (мнимой и реальной частями) как в области низких температур, так и при высоких температурах. Эти особенности объясняются в рамках модели мартенситных фазовых переходов. Методом сканирующей калориметрии найдены температуры структурных фазовых переходов, которые коррелируют с аномалиями электросопротивления в интервале температур 300 T 1000 К для Bi2(Sn1-xCrx)2O7, x The goal of this work is to develop a new technology of sensor materials required for gas sensing devices used in missile. The aim of this work is to study the effect of doping cations with different valency on the crystallographic structure, dielectric and electrical properties of pyrochlore compound Bi2Sn2O7 with selectivity to gases. Polycrystalline compounds Bi2(Sn1-xMex)2O7, where Me = Mn, Cr, x = 0, 0.05 have been synthesized by conventional solid-state reaction. According to the X-ray powder diffraction research, our sample consists of two polymorphs phases: cubic and rhombic. Two new structural transition are found in Bi2(Sn0.95Cr0.05)2O7 solid solutions by scanning calorimetry, as compared to bismuth pyrostannate Bi2Sn2O7. Ions Mn 4+ leads to shift of phase boundary of polymorphic transitions towards lower temperatures, and the phase α→β-transition at about 370 K, which is characteristic for Bi2(Sn1-xCrx)2O7, where x = 0, 0.05 is suppressed. The polymorphic transition at T = 543 K for Bi2(Sn0.95Mn0.05)2O7 occurs with calorification, in contrast to Bi2(Sn1-xCrx)2 7, where x = 0, 0.05. The relationship between structural, electrical and dielectric properties is investigated. Anomalies in the temperature dependence of electrical resistivity and dielectric permeability (real and imaginary part) as in the low region temperatures as in the high region temperature are found. These features are explained within a model of martensitic phase transitions. The temperature of the structural phase transitions correlates with temperature of maximum of the electrical resistivity in the temperature range 300 T 1000 K for Bi2(Sn1-xCrx)2O7, x
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zakharov Y. V., Titov L. S.
Заглавие : Negative magnetoresistance of iron single-crystal whiskers in the course of magnetization reversal
Разночтения заглавия :авие SCOPUS: Negative Magnetoresistance of Iron Single-Crystal Whiskers in the Course of Magnetization Reversal
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2004. - Vol. 46, Is. 2. - P303-305. - ISSN 1063-7834, DOI 10.1134/1.1649428
Примечания : Cited References: 9
Предметные рубрики: RESISTIVITY
WALLS
Аннотация: The change in the low-temperature resistance of iron single-crystal whiskers during magnetization reversal form a single-domain state to a state with a plane-parallel domain structure is studied theoretically. The negative magnetoresistance (similar to45%) is calculated from the Kubo formula with due regard for the change in the trajectories of conduction electrons in a magnetic induction field of domains. The magnetoresistance thus calculated is of the same order of magnitude as the magnetoresistance obtained in the experiment performed by Isin and Coleman.(C) 2004 MAIK "Nauka / Interperiodica".
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Yurkin G. Yu., Patrin G. S., Velikanov D. A., Beletsky V. V.
Заглавие : Transport properties of FeSi with cobalt impurities
Место публикации : TRENDS IN MAGNETISM. - 2011. - Vol. 168-169. - С. 493-496. - ISSN 10120394 (ISSN); 9783037850213 (ISBN), DOI 10.4028/www.scientific.net/SSP.168-169.493
Ключевые слова (''Своб.индексиров.''): iron monosilicide--kondo effect--magnetization--resistivity--spindependent scattering--superparamagnetic cluster--cobalt--crystals--electric resistance--electron energy loss spectroscopy--kondo effect--magnetic field effects--magnetic properties--magnetization--magnetoresistance--scattering--superparamagnetism--transport properties--cobalt--electric conductivity--electron scattering--impurities--kondo effect--magnetism--magnetization--experimental investigations--kondo models--magnetoresistance properties--resistivity--si crystals--spin dependent scattering--superparamagnetic clusters--crystal impurities--crystal impurities
Аннотация: The results of experimental investigations of Fe1-xCo xSi crystals in the impurity limit are presented in this article. We made an attempt to study changes of magnetic properties and conductivity in mixed Fe1-xCoxSi crystals in the impurity limit. Magnetoresistance properties are well described in the framework of Kondo model. The presence of Co-subsystem leads to the occurrence of spin-dependent channel in electron scattering conduction.
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4.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Gokhfeld Yu. S., Solovyov L. A., Vereshchagin S. N., Borus A. A., Gudim I. A., Kazak N. V.
Заглавие : Thermal expansion and resistivity anomalies in Cu2FeBO5 ludwigite
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. G: Frustrated and disordered magnetism. - Ст.G.P9. - P.27-28. - ISBN 978-5-94469-051-7
Примечания : Cited References: 5. - Support by RFBR 20-02-00559 and 21-52-12033 ННИО_а is acknowledged
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kazak N. V., Bayukov O. A., Ovchinnikov S. G., Vasiliev A. D., Rudenko V. V., Ivanova N. B., Knyazev Yu. V., Bartolom J., Arauzo A.
Заглавие : The superexchange interactions in mixed Co-Fe ludwigite
Место публикации : J. Magn. Magn. Mater. - 2011. - Vol. 323, Is. 5. - P.521-527. - MAR. - ISSN 0304-8853, DOI 10.1016/j.jmmm.2010.09.057
Примечания : Cited Reference Count: 15. - Гранты: This study was supported by the Russian Foundation for Basic Research (Project no. 09-02-00171-a), the Federal Agency for Science and Innovation (Rosnauka) (Project no. MK-5632. 2010.2), Physical Division of the Russian Academy of Science, the program "Strongly Correlated Electrons", project 2.3.1.; The financial support of Spanish MINCYT, MAT08/1077 and Aragonese E-34 project are also acknowledged.Финансирующая организация: Russian Foundation for Basic Research [09-02-00171-a]; Federal Agency for Science and Innovation (Rosnauka) [MK-5632. 2010.2]; Physical Division of the Russian Academy of Science; "Strongly Correlated Electrons" [2.3.1]; Spanish MINCYT [MAT08/1077]; Aragonese E-34 project
Предметные рубрики: TRANSPORT-PROPERTIES
SPECTRA
Ключевые слова (''Своб.индексиров.''): ludwigite structure--magnetic susceptibility--magnetic frustration--mott conductivity--ludwigite structure--magnetic frustration--magnetic susceptibility--mott conductivity--ac susceptibility--cation distributions--crystal data--crystallographic sites--electrical resistivity--iron atoms--low temperatures--ludwigite structure--magnetic behavior--magnetic frustrations--magnetic system--magnetic transitions--mossbauer--mossbauer effects--mott conductivity--mott hopping--superexchange energy--superexchange interaction--temperature regions--trivalent iron--variable range--cobalt--electric conductivity--magnetic susceptibility--magnetism--mossbauer spectroscopy--x ray diffraction--crystal structure
Аннотация: The crystal structure, cation distribution and exchange interactions in the Co2.25Fe0.75O2BO3 ludwigite have been explored through X-ray diffraction, electrical resistivity, ac-susceptibility and Mossbauer effect measurements. The crystal data have shown that iron atoms occupy the most symmetric crystallographic sites Fe4 and Fe2. The complex magnetic behavior with two magnetic transitions near 70 and 115 K at low temperatures was found. The Mossbauer data have displayed the trivalent iron states only. The values of superexchange energies have been estimated for Co3O2BO3 and Co2.25Fe0.75O2BO3 yielding a significant role of frustrations in the ludwigite magnetic system. Variable range Mott hopping conductivity law was proved to be valid in the wide temperature region, pointing out a localized character of charge carriers rather than collective. (C) 2010 Elsevier B.V. All rights reserved.
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Frolov G. I., Zhigalov V. S., Polskii A. I., Pozdnyakov V. G.
Заглавие : Study of electroconductivity in cobalt nanocrystalline films
Место публикации : Fiz. Tverd. Tela: MEZHDUNARODNAYA KNIGA, 1996. - Vol. 38, Is. 4. - P1208-1213. - ISSN 0367-3294
Примечания : Cited References: 13
Предметные рубрики: METAL-FILMS
RESISTIVITY
CONDUCTION
ELECTRONS
DENSITY
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Neznakhin D. S., Samoshkina Yu. E., Molokeev M. S., Semenov S. V.
Заглавие : Structural, electrical and magnetic study of manganites Pr0.6Sr0.4MnO3 thin films
Коллективы : Russian Youth Conference on Physics of Semiconductors and Nanostructures, Opto- and Nanoelectronics
Место публикации : J. Phys. Conf. Ser./ Russian Youth Conference on Physics of Semiconductors and Nanostructures, Opto- and Nanoelectronics (17 ; 23 - 27 Nov. 2015): IOP Publishing, 2016. - Vol. 690, Is. 1. - ISSN 17426588 (ISSN), DOI 10.1088/1742-6596/690/1/012002
Примечания : Cited References: 20. - The work was supported partly by RFBR, grant №14-02-01211, Grant of President of Russian Federation №NSh-2886.2014.2, and by The Ministry of Education and Science of the Russian Federation, project №2582.
Ключевые слова (''Своб.индексиров.''): magnetic materials--magnetization--manganese oxide--nanoelectronics--nanostructures--oxide films--field dependence--magnetization temperature curves--polycrystalline phase--polycrystalline pr--resistivity dependence--shape characteristics--structural parameter--zero-field cooling--thin films
Аннотация: Thin polycrystalline Pr0.6Sr0.4MnO3 films were grown on the Y stabilized zirconium oxide substrates by magnetron sputtering using RF power and off-axis sputtering scheme with double cathodes. Only one polycrystalline phase with structural parameters consistent with that for the corresponding bulk sample was revealed in the films. Electric resistivity dependence on temperature demonstrates the shape characteristic for the substances with the Mott transition. The difference between magnetization temperature curves measured in the zero field cooling and field cooling modes was revealed. Magnetization field dependences were presented by the hysteresis loops changing their form with temperature. © Published under licence by IOP Publishing Ltd.
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Pazniak H., Stevens M., Dahlqvist M., Zingsem B., Kibkalo L., Felek M., Varnakov S. N., Farle M., Rosen J., Wiedwald U.
Заглавие : Phase stability of nanolaminated epitaxial (Cr1-xFex)2AlC MAX phase thin films on MgO(111) and Al2O3(0001) for use as conductive coatings
Место публикации : ACS Appl. Nano Mat. - 2021. - Vol. 4, Is. 12. - P.13761-13770. - ISSN 25740970 (ISSN), DOI 10.1021/acsanm.1c03166
Примечания : Cited References: 51. - This work has been supported by the Deutsche Forschungsgemeinschaft (DFG) within CRC/TRR 270, project B02 (Project-ID 405553726). The calculations were carried out using supercomputer resources provided by the Swedish National Infrastructure for Computing (SNIC) at the National Supercomputer Centre (NSC) and the High Performance Computing Center North (HPC2N) partially funded by the Swedish Research Council through grant agreement no. 2018-05973. J.R. acknowledges funding from the Knut and Alice Wallenberg Foundation. Support by the Interdisciplinary Center for Analytics on the Nanoscale (ICAN) of the University of Duisburg-Essen (DFG RIsources reference: RI_00313), a DFG-funded core facility (Project nos. 233512597 and 324659309), is gratefully acknowledged. M.F. acknowledges co-funding by the government of the Russian Federation (agreement no. 075-15-2019-1886)
Аннотация: In this study, we model the chemical stability in the (Cr1-xFex)2AlC MAX phase system using density functional theory, predicting its phase stability for 0 ‹ x ‹ 0.2. Following the calculations, we have successfully synthesized nanolaminated (Cr1-xFex)2AlC MAX phase thin films with target Fe contents of x = 0.1 and x = 0.2 by pulsed laser deposition using elemental targets on MgO(111) and Al2O3(0001) substrates at 600 °C. Structural investigations by X-ray diffraction and transmission electron microscopy reveal MAX phase epitaxial films on both substrates with a coexisting (Fe,Cr)5Al8 intermetallic secondary phase. Experiments suggest an actual maximum Fe solubility of 3.4 at %, corresponding to (Cr0.932Fe0.068)2AlC, which is the highest Fe doping level achieved so far in volume materials and thin films. Residual Fe is continuously distributed in the (Fe,Cr)5Al8 intermetallic secondary phase. The incorporation of Fe results in the slight reduction of the c lattice parameter, while the a lattice parameter remains unchanged. The nanolaminated (Cr0.932Fe0.068)2AlC thin films show a metallic behavior and can serve as promising candidates for highly conductive coatings.
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Korshunov M. M., Kozeeva L. P., Lavrov A. N.
Заглавие : Peculiarity of interrelation between electronic and magnetic properties of HTSC cuprates associated with short-range antiferromagnetic order
Коллективы :
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2010. - Vol. 111, Is. 1. - P104-113. - ISSN 1063-7761, DOI 10.1134/S1063776110070101
Примечания : Cited References: 48. - This study was financially supported by the Russian Foundation for Basic Research (project nos. 09-02-01224 and 09-02-00127) and under the program "Quantum Physics of Condensed Media" of the Presidium of the Russian Academy of Sciences (project no. 5.7).
Предметные рубрики: T-J MODEL
NORMAL-STATE
FERMI-SURFACE
RESISTIVITY ANISOTROPY
3-CENTER INTERACTIONS
OPTICAL CONDUCTIVITY
COPPER OXIDES
CUO2 PLANES
SUPERCONDUCTORS
TRANSPORT
Ключевые слова (''Своб.индексиров.''): anisotropic resistivity--antiferromagnetic orders--concentration dependence--cuprates--doping levels--electronic and magnetic properties--fermi surface topology--high temperature superconducting--magnetic orders--magnetic state--maximum values--pseudo-gap--short-range magnetic orders--strong electron correlations--temperature dependence--anisotropy--antiferromagnetic materials--antiferromagnetism--copper compounds--correlators--electronic properties--high temperature superconductors--hole concentration--magnetic properties--neon--superconducting magnets--single crystals
Аннотация: We report on the results of measurements of anisotropic resistivity of RBa(2)Cu(3)O(6 + x) (R = Tm, Lu) high-temperature superconducting single crystals in a wide range of doping levels, indicating a nontrivial effect of magnetic order on the electronic properties of cuprates. In particular, our results visually demonstrate the crossover from the state with moderate anisotropy of resistivity rho (c) /rho (ab) similar to 30 to a strongly anisotropic state with rho (c) /rho (ab) similar to 7 x 10(3) upon cooling as well as upon a decrease in the hole concentration in the CuO(2) planes. It is also shown that anisotropy is sensitive to the magnetic state of CuO(2) planes and attains its maximum value after the establishment of the long-range antiferromagnetic order. The results are discussed in the framework of the theory based on the t-t'-taEuro(3)-J model of CuO(2) layers taking into account strong electron correlations and short-range magnetic order. In this theory, anomalies of spin correlators and Fermi surface topology for a critical hole concentration of p* a parts per thousand 0.24 are demonstrated. The concentration dependence of the charge carrier energy indicates partial suppression of energy due to the emergence of a pseudogap at p p*. This theory explains both the experimentally observed sensitivity of anisotropy in conductivity to the establishment of the antiferromagnetic order and the absence of anomalies in the temperature dependence of resistivity rho (ab) (T) in the vicinity of the N,el temperature.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kazak N. V., Balaev A. D., Ivanova N. B., Ovchinnikov S. G.
Заглавие : Mossbauer magnetization and resistivity studies of Fe1.91V0.09BO4
Разночтения заглавия :авие SCOPUS: Mossbauer magnetization and resistivity studies of Fe1.91V 0.09BO4
Место публикации : Physica B: ELSEVIER SCIENCE BV, 2005. - Vol. 359: International Conference on Strongly Correlated Electron Systems (SCES 04) (JUL 26-30, 2004, Karlsruhe, GERMANY). - P1324-1326. - ISSN 0921-4526, DOI 10.1016/j.physb.2005.01.396
Примечания : Cited References: 8
Предметные рубрики: FE2OBO3
Ключевые слова (''Своб.индексиров.''): mott-hubbard system--magnetism--new materials--magnetism--mott-hubbard system--new materials--crystallization--crystallography--fermi level--ferrimagnetism--magnetism--magnetization--mossbauer spectroscopy--phase transitions--single crystals--x ray diffraction analysis--charge ordering--electron-electron interactions--mott-hubbard system--new materials--iron compounds
Аннотация: Single crystals of Fe1.91V0.09BO4 were prepared by spontaneous crystallization using a solution melt technology for the first time and its structure, electronic and magnetic properties were investigated by X-ray diffraction, Mossbauer spectroscopy, magnetization and electrical measurements. Room-temperature Mossbauer measurements indicate that "localized" (Fe2+, Fe3+) and "delocalized" (Fe2.5+) states in ratio 0.31:0.345:0.345 distributed over two crystallographically non-equivalent positions exist. The results of magnetic measurements show that warwickite is a P-type ferrimagnet below T = 130 K. Resistivity measurements show a variable-range-hopping when electron-electron interactions cause a soft Coulomb gap in the density of states at the Fermi energy. (c) 2005 Elsevier B.V. All rights reserved.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Moiseenko E. T., Altunin R. R., Zharkov S. M.
Заглавие : In situ electron diffraction and resistivity characterization of solid state reaction process in Cu/Al bilayer thin films
Место публикации : Metall. Mat. Trans. A. - 2020. - Vol. 51, Is. 3. - P.1428-1436. - ISSN 10735623 (ISSN), DOI 10.1007/s11661-019-05602-5
Примечания : Cited References: 52. - The authors wish to thank the financial support from the Russian Science Foundation (Grant #18-13-00080)
Аннотация: Solid state reaction processes in Cu/Al thin films have been studied using the methods of in situ electron diffraction and electrical resistivity measurements. The solid state reaction in the Cu/Al thin films has been found to begin already at 88 °C with the formation of the Al2Cu phase in the process of thermal heating in vacuum. The phase sequence at the solid state reaction in the films under study has been determined to be the following: Al2Cu → AlCu → Al4Cu9. A model has been suggested for describing the initial formation stage of intermetallic compounds at the solid state reaction in Cu/Al thin films. According to this model, at the initial stage, the intermetallic compounds are formed as separate crystallites at the interface in the Cu/Al thin films. The suggested model can be applied both to the formation of the first phase, Al2Cu, and to the subsequent phases: AlCu and Al4Cu9. For the Al4Cu9 phase the temperature coefficient of the electrical resistivity has been determined to be equal to αAl4Cu9= 1.1 × 10−3 K−1.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Romanova O. B., Aplesnin S. S., Udod L. V., Sitnikov M. N., Kretinin V. V., Yanushkevich K. I., Velikanov D. A.
Заглавие : Magnetoresistance, magnetoimpedance, magnetothermopower, and photoconductivity in silver-doped manganese sulfides
Коллективы : Russian Foundation for Basic Research [18-52-00009 Bel_a]; Government of Krasnoyarsk Territory; Krasnoyarsk Regional Fund of Science [18-42-240001 r_a]
Место публикации : J. Appl. Phys. - 2019. - Vol. 125, Is. 17. - Ст.175706. - ISSN 0021-8979, DOI 10.1063/1.5085701. - ISSN 1089-7550(eISSN)
Примечания : Cited References: 29. - This study was supported by the Russian Foundation for Basic Research (Project No. 18-52-00009 Bel_a). The reported study was funded by the Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science (Project No. 18-42-240001 r_a), to the research project: "Inversion of the Sign of the Components of the Magnetoelectric Tensor on the Temperature in Films of Bismuth Garnet Ferrite Replaced by Neodymium." This study was carried out in the framework of the state task No. 3.5743.2017/6.7.
Предметные рубрики: MAGNETIC-PROPERTIES
RESISTIVITY
Аннотация: New multifunction materials in the AgXMn1‒XS (Х = 0.05) system have been synthesized and investigated in the temperature range of 77‒500 K in magnetic fields up to 12 kOe. Near the temperature of the magnetic transition (ТN = 176 K), the anomalous behavior of the temperature dependence of magnetization has been observed and has been attributed to the formation of ferrons. An analysis of the infrared spectroscopy data and I‒V characteristics has revealed the spin-polaron subband splitting. Several conductivity channels have been found from the impedance spectra. The temperature and magnetic field dependences of the carrier relaxation time have been obtained. The magnetoresistance (−21%), magnetoimpedance (−65%), magnetothermopower (−40%), and photoconductivity effects have been detected. The majority carrier type, density, and mobility have been determined from the Hall-effect measurement data. The observed effects have been explained using a ferron model.Синтезированы и исследованы новые многофункциональные материалы системы AgXMn1-XS (Х=0.05) в интервале температур 77-500К в магнитных полях до 12 кЭ. В близи температуры магнитного перехода (ТN=176К) наблюдается аномальное поведение температурной зависимости намагниченности, вызванное образованием ферронов. Найдено расщепление спин-поляронной подзоны из ИК спектроскопии и вольт-амперных характеристик. Установлено несколько каналов проводимости из спектров импеданса, отличающихся частоте. Определена зависимость времени релаксации носителей заряда от температуры и магнитного поля. Обнаружено четыре эффекта: магнитосопротивление (-21%), магнитоимпеданс (-65%), магнитотермоЭДС (-40%) и фотопроводимость. Найдены: тип, концентрация и подвижность основных носителей заряда из холловских измерений. Обнаруженные эффекты объясняются в модели ферронов.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shaykhutdinov K. A., Semenov S. V., Popkov S. I., Balaev D. A., Bykov A. A., Dubrovskiy A. A., Petrov M. I., Volkov N. V.
Заглавие : Magnetoresistance of substituted lanthanum manganites La0.7Ca0.3MnO3 upon nonequilibrium overheating of carriers
Разночтения заглавия :авие SCOPUS: Magnetoresistance of substituted lanthanum manganites La 0.7Ca 0.3MnO 3 upon nonequilibrium overheating of carriers
Место публикации : J. Appl. Phys.: AMER INST PHYSICS, 2011. - Vol. 109, Is. 8. - Ст.83711. - ISSN 0021-8979, DOI 10.1063/1.3573666
Примечания : Cited References: 15. - This study was partially supported by the Russian Foundation for Basic Research, project no. 08-02-00259a, and the Lavrent'ev's Competition of Young Scientists of the Siberian Branch of the RAS, project no. 12.
Ключевые слова (''Своб.индексиров.''): field dependence--lanthanum manganites--low thermal conductivity--manganite materials--negative differential resistivity--non equilibrium--non-linearity--nonequilibrium heating--polycrystalline--positive magnetoresistance--transport currents--electric resistance--electron gas--heating--lanthanum--lanthanum alloys--magnetic fields--magnetoelectronics--magnetoresistance--manganese oxide--manganites--thermal conductivity--current voltage characteristics
Аннотация: Current-voltage characteristics of the polycrystalline substituted lanthanum manganite La0.7Ca0.3MnO3 were experimentally studied at T - 77.4 K in magnetic fields up to 13 kOe. In these characteristics, a portion of negative differential resistivity was observed above a certain threshold value of critical current density j caused, in our opinion, by nonequilibrium heating of the electron gas due to low thermal conductivity of the manganite material. Because of the nonlinearity of the current-voltage characteristics, the field dependences of resistivity rho( H) appear extremely sensitive to the value of a transport current. In this case, the rho( H) dependences reveal both ordinary negative and positive magnetoresistance. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3573666]
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shaikhutdinov K. A., Popkov S. I., Semenov S. V., Balaev D. A., Dubrovskiy A. A., Sablina K. A., Volkov N. V.
Заглавие : Low-temperature resistivity of polycrystalline (La0.5Eu 0.5)0.7Pb0.3MnO3 in a magnetic fields
Место публикации : J. Phys. Conf. Ser. - 2010. - Vol. 200, Is. SECTION 5. - ISSN 17426588 (ISSN) , DOI 10.1088/1742-6596/200/5/052025
Ключевые слова (''Своб.индексиров.''): antiferromagnetic grains--comparative analysis--ferromagnetic grain--low temperatures--polycrystalline--specific heat measurement--spin dependent tunneling--transport and magnetic properties--antiferromagnetism--electric resistance--europium--grain boundaries--grain size and shape--lanthanum compounds--lead--magnetic field effects--magnetic properties--magnetoresistance--manganese oxide--single crystals--thermal variables measurement--lanthanum
Аннотация: The effect of grain boundaries on magnetoresistance (MR) of manganites have been investigated by the comparative analysis of the properties of single-crystal and polycrystalline (La0.5Eu0.5) 0.7Pb0.3MnO3. While MR of the single crystal is maximum near the Curie temperature and vanishes in the low-temperature region, the polycrystalline (La0.5Eu0.5)0.7Pb 0.3MnO3 sample exhibits high MR in the low-temperature region. In order to clarify the origin of the low-temperature MR, the transport and magnetic properties of the polycrystalline (La0.5Eu 0.5)0.7Pb0.3MnO3 in magnetic fields have been supplemented by study of magnetic properties and specific heat measurements. The results obtained could be attributed to spin-dependent tunneling between ferromagnetic grains through insulating antiferromagnetic grain boundaries. © 2010 IOP Publishing Ltd.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shaykhutdinov K. A., Popkov S. I., Semenov S. V., Balaev D. A., Dubrovskiy A. A., Sablina K. A., Sapronova N. V., Volkov N. V.
Заглавие : Low-temperature resistance and magnetoresistance hysteresis in polycrystalline (La0.5Eu0.5)(0.7)Pb0.3MnO3
Разночтения заглавия :авие SCOPUS: Low-temperature resistance and magnetoresistance hysteresis in polycrystalline (La0.5Eu0.5)0.7Pb 0.3MnO3
Место публикации : J. Appl. Phys.: AMER INST PHYSICS, 2011. - Vol. 109, Is. 5. - Ст.53711. - ISSN 0021-8979, DOI 10.1063/1.3559303
Примечания : Cited References: 20. - This study was partially supported by the Russian Foundation for Basic Research, Project No. 08-02-00259a and the Lavrentyev Competition of the Young Scientists' Projects of the Siberian Branch of the Russian Academy of Sciences, Project No. 12.
Предметные рубрики: RESISTIVITY MINIMUM
MANGANITES
FILMS
Ключевые слова (''Своб.индексиров.''): antiferromagnets--electrical resistances--ferromagnets--field dependence--inter-grain--lanthanum manganites--low temperatures--low-temperature resistance--polycrystalline--temperature dependence--tunnel contacts--antiferromagnetic materials--europium--ferromagnetic materials--ferromagnetism--hysteresis--lead--magnetic field effects--magnetoelectronics--magnetoresistance--magnets--manganese oxide--paramagnetism--superconducting materials--electric resistance
Аннотация: The behavior of temperature dependences of electrical resistance and magnetoresistance of polycrystalline substituted lanthanum manganite (La0.5Eu0.5)(0.7)Pb0.3MnO3 at low temperatures was thoroughly studied. A broad hysteresis was found in the field dependences of electrical resistance in the low-temperature region. Above 40 K, no hysteresis feature was observed. The temperature T = 40 K corresponds to the temperature of minimum electrical resistance and the temperature T-N to the antiferromagnet-paramagnet phase transition of the material of the intergrain boundaries. In this work we propose a model which explains the observed features of the rho(T) and rho(H) curves at temperatures below T-N by the formation of a network of ferromagnet-antiferromagnet-ferromagnet tunnel contacts. (C) 2011 American Institute of Physics. [doi:10.1063/1.3559303]
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Korovushkin M. M.
Заглавие : Electrical resistivity and the Hall effect in the doped Mott-Hubbard material with strong spin-charge coupling
Колич.характеристики :14 с
Место публикации : Phys. Scr. - 2023. - Vol. 98, Is. 12. - Ст.125922. - ISSN 00318949 (ISSN), DOI 10.1088/1402-4896/ad05ed. - ISSN 14024896 (eISSN)
Примечания : Cited References: 96. - Author is grateful to V V Val’kov, A D Fedoseev, D M Dzebisashvili and M S Shustin for fruitful discussions and permanent interest in this work. Author thanks V A Mitskan and A O Zlotnikov for technical support
Аннотация: The kinetic characteristics of the doped Mott-Hubbard material are considered within the realistic spin-fermion model which takes into account the strong spin-charge coupling. The kinetic equation constructed on the basis of the mechanism of carrier scattering on the spin fluctuations is solved using the multi-moment method, which allows one to analyze the temperature behavior of nonequilibrium distribution function in the problems of electrical resistivity ρ and the Hall coefficient RH. The calculated dependences ρ(T) and RH(T) for the underdoped and optimally doped regimes demonstrate good qualitative agreement with the experimental data. In particular, the Hall coefficient calculated for the underdoped regime reproduces the experimentally observed sharp drop and even a change in sign at low temperatures.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan, M. Yu., Val'kov V. V., Aksenov S. V.
Заглавие : Effects of anisotropy and Coulomb interactions on quantum transport in a quadruple quantum-dot structure
Место публикации : Phys. Rev. B: American Physical Society, 2017. - Vol. 95, Is. 3. - Ст.035411. - ISSN 2469-9950, DOI 10.1103/PhysRevB.95.035411. - ISSN 2469-9969(eISSN)
Примечания : Cited References:62. - We acknowledge fruitful discussions with P. I. Arseyev, N. S. Maslova, V. N. Mantsevich, and R. Sh. Ikhsanov. This work was financially supported by the Comprehensive programme SB RAS No. 0358-2015-0007, the RFBR, Government of Krasnoyarsk Territory, Krasnoyarsk Region Science and Technology Support Fund, Projects No. 15-02-03082, No. 15-42-04372, No. 16-42-243056, and No. 16-42-242036. M. Yu. K. thanks the Program of Basic Research of the National Research University Higher School of Economics for support.
Предметные рубрики: 2-BAND HUBBARD-MODEL
ONE NARROW-BAND
ANOMALOUS RESISTIVITY
Аннотация: We present an analytical and numerical investigation of the spectral and transport properties of a quadruple quantum-dot (QQD) structure which is one of the popular low-dimensional systems in the context of fundamental quantum physics study, future electronic applications, and quantum calculations. The density of states, occupation numbers, and conductance of the structure were analyzed using the nonequilibrium Green's functions in the tight-binding approach and the equation-of-motion method. In particular the anisotropy of hopping integrals and on-site electron energies as well as the effects of the finite intra- and interdot Coulomb interactions were investigated. It was found out that the anisotropy of the kinetic processes in the system leads to the Fano-Feshbach asymmetrical peak. We demonstrated that the conductance of the QQD device has a wide insulating band with steep edges separating triple-peak structures if the intradot Coulomb interactions are taken into account. The interdot Coulomb correlations between the central QDs result in the broadening of this band and the occurrence of an additional band with low conductance due to the Fano antiresonances. It was shown that in this case the conductance of the anisotropic QQD device can be dramatically changed by tuning the anisotropy of on-site electron energies.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Y., Val'kov V. V.
Заглавие : Anomalous resistivity and the electron-polaron effect in the two-band hubbard model with one narrow band
Место публикации : J. Supercond. Nov. Magn.: SPRINGER, 2012. - Vol. 25, Is. 5. - P.1379-1382. - ISSN 1557-1939, DOI 10.1007/s10948-012-1523-3
Примечания : Cited References: 28. - We are grateful to P. Fulde, Yu. Kagan, K. I. Kugel, N.V. Prokof'ev, P. Nozieres, and C. M. Varma for the numerous stimulating discussions. We acknowledge financial support of the RFBR Grant No. 11-02-00741.
Предметные рубрики: FERMI GAS
SUPERCONDUCTIVITY
SUPERFLUIDITY
TEMPERATURE
REPULSION
SYSTEMS
Ключевые слова (''Своб.индексиров.''): electron-polaron effect--two-band hubbard model--marginality--anomalous resistivity
Аннотация: We search for anomalous normal and superconductive behavior in the two-band Hubbard model with one narrow band. We analyze the influence of the electron–polaron effect and the Altshuler–Aronov effect on effective mass enhancement and scattering times of heavy and light components in the clean case. We find anomalous behavior of resistivity at high temperatures TW∗hT W_{h}. *} both in 3D and 2D situations. The SC instability in the model is governed by an enhanced Kohn–Luttinger effect for p-wave pairing of heavy electrons via polarization of light electrons.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Y., Valkov V. V.
Заглавие : Anomalous resistivity and superconductivity in the two-band Hubbard model with one narrow band (Review)
Место публикации : Low Temp. Phys. - 2011. - Vol. 37, Is. 1. - P.69-82. - ISSN 1063-777X, DOI 10.1063/1.3552118; \b Физика низких температур
Примечания : Cited References: 62. - We thank A.S. Alexandrov, A.F. Andreev, M.A. Baranov, Yu. Bichkov, A.V. Chubukov, D.V. Efremov, A.S. Hewson, K.A. Kikoin, F.V. Kusmartsev, P. Nozieres, T.M. Rice, A.O. Sboychakov, P. Thalmeer, C.M. Varma, D. Vollhardt, P. Woelfle, A. Yaresko and, especially, P. Fulde, Yu. Kagan, K.I. Kugel, and N.V. Prokof'ev for many simulating discussions on this subject and acknowledge the financial support of RFBR grants # 08-02-00224 and 08-02-00212. M.Yu.K. is also grateful to the Leverhulme trust for a grant to visit Loughborough University, where this work was completed.
Предметные рубрики: FERMI-LIQUID BEHAVIOR
MAGNETIC-ALLOYS
HEAVY
DENSITY
SYSTEMS
STATE
UPT3
MECHANISM
PARTICLE
VALENCE
Аннотация: We search for marginal Fermi-liquid behavior in the two-band Hubbard model with one narrow band. We consider the limit of low electron densities in the bands and strong intraband and interband Hubbard interactions. We analyze the influence of electron-polaron effects and other mechanisms for mass-enhancement (related to the momentum dependence of the self-energies) on the effective mass and scattering times of light and heavy components in the clean case (electron-electron scattering and no impurities). We find a tendency towards phase separation (towards negative partial compressibility of heavy particles) in the 3D case with a large mismatch between the densities of heavy and light bands in the strong coupling limit. We also find that for low temperatures and equal densities, the resistivity in a homogeneous state R(T) proportional to T-2 behaves as a Fermi-liquid in both 3D and 2D. For temperatures greater than the effective bandwidth for heavy electrons T W-h*, the coherence of the heavy component breaks down completely. The heavy particles move diffusively in the surrounding light particles. At the same time, light particles scatter on heavy particles as if on immobile (static) impurities. Under these conditions, the heavy component is marginal, while the light component is not. The resistivity approaches saturation for T W-h* in the 3D case. In 2D the resistivity has a maximum and a localization tail owing to weak-localization corrections of the Altshuler-Aronov type. This behavior of resistivity in 3D could be relevant for some uranium-based heavy-fermion compounds such as UNi2Al3 and in 2D, for some other mixed-valence compounds, possibly including layered manganites. We also consider briefly the superconductive (SC) instability in this model. The leading instability tends to p-wave pairing and is governed by an enhanced Kohn-Luttinger mechanism for SC at low electron densities. The critical temperature corresponds to the pairing of heavy electrons via polarization of the light electrons in 2D. (C) 2011 American Institute of Physics. [doi:10.1063/1.3552118]
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S., Petrakovskii G. A., Ryabinkina L. I., Abramova G. M., Kiselev N. I., Romanova O. B.
Заглавие : Influence of magnetic ordering on the resistivity anisotropy of alpha-MnS single crystal
Разночтения заглавия :авие SCOPUS: Influence of magnetic ordering on the resistivity anisotropy of α-MnS single crystal; авие SCOPUS: Influence of magnetic ordering on the resistivity anisotropy of ?-MnS single crystal
Место публикации : Solid State Commun.: PERGAMON-ELSEVIER SCIENCE LTD, 2004. - Vol. 129, Is. 3. - P195-197. - ISSN 0038-1098, DOI 10.1016/j.ssc.2003.09.028; Solid State Commun. - 2004. - Vol. 129, Is. 3. - P195-197. - Вариант Sopus
Примечания : Cited References: 7
Ключевые слова (''Своб.индексиров.''): anisotropy of resistivity--optical gap--d. anisotropy of resistivity--d. optical gap--antiferromagnetism--band structure--bandwidth--diffractometers--electron transitions--fermi level--hamiltonians--light absorption--magnetic anisotropy--magnetization--single crystals--spectroscopic analysis--x ray diffraction analysis--coulomb repulsion--resistivity anisotropy--semiconducting manganese compounds--d. anisotropy of resistivity--d. optical gap--antiferromagnetism--band structure--bandwidth--diffractometers--electron transitions--fermi level--hamiltonians--light absorption--magnetic anisotropy--magnetization--single crystals--spectroscopic analysis--x ray diffraction analysis--coulomb repulsion--resistivity anisotropy--semiconducting manganese compounds
Аннотация: The resistivity and the optical absorbtion spectra of single crystal alpha-MnS are studied in the temperature range 80-300 K along two directions [100] and [111]. Strong anisotropy of the resistivity, and the shift of absorbtion spectra band edge below T 160 K are explained in terms of model involving delocalized holes in 3d-band manganese ions interacting with localized spins by using the sd-model. (C) 2003 Elsevier Ltd. All rights reserved.
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