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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Балаев, Дмитрий Александрович, Дубровский, Андрей Александрович, Попков, Сергей Иванович, Гохфельд, Денис Михайлович, Семёнов, Сергей Васильевич, Шайхутдинов, Кирилл Александрович, Петров, Михаил Иванович
Заглавие : Особенности гистерезисного поведения магнитосопротивления гранулярных ВТСП
Место публикации : Физ. тверд. тела: Наука, 2012. - Т. 54, Вып. 11. - С. 2027-2035. - ISSN 0367-3294
Примечания : Библиогр.: 52 назв. - Работа поддержана РФФИ в рамках регионального конкурса СИБИРЬ, проект N 11-02-98007 р-сибирь\_а.
Аннотация: Изучено поведение гистерезиса магнитосопротивления R(H) гранулярных ВТСП в условиях, когда резистивный отклик подсистемы межгранульных границ близок к насыщению. Проведены измерения гистерезисных зависимостей R(H) образцов Y_1-xPr_xBa_2Cu_3O_7 при x = 0.11 и x = 0.04 с температурами перехода T_C~ 85.5 и 91.0 K соответственно. Исследована эволюция полевой ширины гистерезиса R(H) при варьировании измерительного тока. Установлен предел применимости концепции эффективного поля в межгранульной среде, предложенной ранее для описания гистерезисного поведения R(H) и термомагнитной предыстории гранулярных ВТСП. В исследованных образцах приближение эффективного поля в межгранульной среде применимо до тех пор, пока магнитосопротивление подсистемы межгранульных границ не превышает (90 ± 5)% от своей максимальной величины.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Dubrovskiy A. A., Shaykhutdinov K. A., Bayukov O. A., Yakushkin S. S., Bukhtiyarova G. A., Martyanov O. N.
Заглавие : Surface effects and magnetic ordering in few-nanometer-sized ε-Fe 2O3 particles
Место публикации : J. Appl. Phys. - 2013. - Vol. 114, Is. 16. - Ст.163911. - P. - ISSN 0021-8979, DOI 10.1063/1.4827839
Аннотация: The magnetic properties of ?-Fe2O3 nanoparticles with an average size of 3.4 nm in a silica gel matrix are investigated using Mossbauer technique, electron spin resonance, and magnetic measurements. Two magnetic subsystems reveal in magnetic measurements. Paramagnetic subsystem is formed by the Fe(III) ions in the smallest (<3.5 nm) particles' shell, while ferrimagnetic ordering in the "core" of the particles results in superparamagnetic behavior. The superparamagnetic behavior of the investigated samples is observed up to ?800 K. The magnetic moment of the particles is formed by both the ferrimagnetic ordering characteristic of ?-Fe 2O3 and the additional effect of uncompensated sublattices (planes). В© 2013 AIP Publishing LLC.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Yakushkin S. S., Dubrovskiy A. A., Balaev A. D., Shaykhutdinov K. A., Bukhtiyarova G. A., Martyanov O. N.
Заглавие : Magnetic properties of few nanometers ɛ-Fe2O3 nanoparticles supported on the silica
Место публикации : J. Appl. Phys.: American Institute of Physics, 2012. - Vol. 111, Is. 4. - Ст.44312. - ISSN 0021-8979, DOI 10.1063/1.3686647
Примечания : Cited References: 27. - authors thank A. D. Balaev and N. V. Volkov for fruitful discussions and comments. This work was supported by Program of RAS No. 27.46.
Предметные рубрики: HIGH-TEMPERATURE
IRON
STABILIZATION
OXIDE
GEL
Аннотация: Magnetic properties of ɛ-Fe2O3nanoparticles supported on silica with the average size of few nanometers, narrow size distribution and no admixture of any other iron oxide polymorphs are investigated. The investigation of the temperature behavior of magnetization within the temperature range from 4.2 to 1000 K revealed the presence of several magnetic subsystems in the species under study. The temperatures’ behavior of the magnetic moment value indicates ferrimagnetic ordering in the ɛ-Fe2O3nanoparticles with a Curie temperature of about 800 K and points to the existence of a significant paramagnetic contribution becoming apparent at low temperatures. According to the electron spin resonance data, the particles possess superparamagnetic behavior at temperature higher ∼120 K. The model of the magnetic structure of monophase system of few nanometers ɛ-Fe2O3nanoparticles supported on silica is proposed.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Freydman A. L., Balaev A. D., Dubrovskiy A. A., Eremin E. V., Temerov V. L., Gudim, I. A.
Заглавие : Direct and inverse magnetoelectric effects in HoAl3(BO3)4 single crystal
Коллективы : Russian Foundation for Basic Research [13-02-12442ofi_m2, 14-02-00307]
Место публикации : J. Appl. Phys.: American Institute of Physics, 2014. - Vol. 115, Is. 17. - Ст.174103. - ISSN 0021-8979, DOI 10.1063/1.4874270. - ISSN 1089-7550
Примечания : Cited References: 34. - This work was supported by Russian Foundation for Basic Research (Project Nos. 13-02-12442ofi_m2 and 14-02-00307). The authors are grateful to V. N. Ilyushchenko for the help in preparing of this manuscript.
Предметные рубрики: POLARIZATION
BEHAVIOR
ORDER
Аннотация: The direct (MEH-) and inverse (MEE-) magnetoelectric effects in the HoAl3(BO3)4 single crystal are studied. Temperature and magnetic field dependences of permittivity of the crystal are investigated. A relation between the investigated effects was established. It was found that the magnetoelectric effect can exist in crystals without magnetic order or spontaneous polarization. It was shown that the phenomena investigated are due to magnetostriction or magnetoelastic effect. The thermodynamic potential was considered for describing magnetoelectric effect at low magnetic fields. The results obtained are explained within a proposed qualitative microscopic model, based on interplay of configuration of 4f- electron subshell of the rare-earth element and applied magnetic or electric field.Изучаются прямой (MEH-) и обратный (МЭА-) магнитоэлектрические эффекты в монокристалле HoAl3(BO3)4 . Зависимости диэлектрической проницаемости кристалла от температуры и магнитного поля исследованы. Была создана связь между исследованными эффектами. Было обнаружено, что магнитоэлектрический эффект может существовать в кристаллах без магнитного порядка или спонтанной поляризации. Было показано, что исследуемые явления происходят из-за магнитострикции или магнитоупругого эффекта. Термодинамический потенциал рассчитывался для описания магнитоэлектрический эффект в слабых магнитных полях. Полученные результаты объясняются в рамках предложенной качественной микроскопической модели, основанной на взаимодействии конфигурации 4f-электронов в подоболочке редкоземельного элемента и внешнего магнитного или электрического поля.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Poperechny I. S., Krasikov A. A., Shaikhutdinov K. A., Dubrovskiy A. A., Popkov S. I., Balaev A. D., Yakushkin S. S., Bukhtiyarova G. A., Martyanov O. N., Raikher, Yu. L.
Заглавие : Dynamic magnetization of ε-Fe2O3 in pulse field: Evidence of surface effect
Место публикации : J. Appl. Phys.: American Institute of Physics, 2015. - Vol. 117, Is. 6. - Ст.063908. - ISSN 0021, DOI 10.1063/1.4907586. - ISSN 10897550(eISSN)
Примечания : Cited References:30. - The work was supported by RFBR Grant Nos. 14-02-96002 and 12-02-00897, and project MIG S26/617 from the Ministry of Education and Science of Perm Region.
Предметные рубрики: FERROMAGNETIC-RESONANCE
COERCIVE FIELD
NANOPARTICLES
ANISOTROPY
Аннотация: The magnetization dynamics of ε-Fe2O3 nanoparticles with an average size of about 9 nm is investigated. From comparison of the hysteresis loops obtained in quasi-static conditions and under pulse fields with amplitudes up to 200 kOe and pulse lengths 8–32 ms, it follows that the effective coercivity increases considerably with the variation rate of the imposed magnetic field. A theoretical explanation of this behavior is proposed. The model takes into account the superparamagnetic effects as well as the fact that magnetic anisotropy of the nanoparticles, along with the bulk term, includes a surface contribution. The latter, being of minor importance for the observed magnetic behavior of 25–100 nm particles, becomes essential when the particle size is below 10 nm. From the experimental data, a reference value of the surface anisotropy of nanodisperse ε-Fe2O3 is established, and evidence is presented to the effect that below 300 K this contribution does not significantly depend on temperature.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Dubrovskiy A. A., Balaev A. D., Shaykhutdinov K. A., Bayukov O. A., Pletnev O. N., Yakushkin S. S., Bukhtiyarova G. A., Martyanov O. N.
Заглавие : Size effects in the magnetic properties of ε-Fe2O3 nanoparticles
Место публикации : J. Appl. Phys.: American Institute of Physics, 2015. - Vol. 118, Is. 21. - Ст.213901. - ISSN 00218979 (ISSN), DOI 10.1063/1.4936838
Примечания : Cited References: 41. - We are grateful to Professor Yu. L. Raikher for useful discussions and M. A. Kazakova for the help in sample preparationThis work was supported by Russian Federal Agency of Scientific Organizations (Project No. V.44.1.15) and scientific and educational center of energy-efficient catalysis of NSU
Предметные рубрики: FERROMAGNETIC-RESONANCE
OXIDE NANOPARTICLES
WAVE ABSORBER
IRON
TRANSITION
TEMPERATURE
PARTICLES
PHASE
FNANOWIRES
FIELD
Аннотация: We report the results of comparative analysis of magnetic properties of the systems based on ε-Fe2O3, nanoparticles with different average sizes (from ∼3 to 9 nm) and dispersions. The experimental data for nanoparticles higher than 6-8 nm in size are consistent with the available data, specifically, the transition to the magnetically ordered state occurs at a temperature of ∼500 K and the anomalies of magnetic properties observed in the range of 80-150 K correspond to the magnetic transition. At the same time, Mossbauer and ferromagnetic resonance spectroscopy data as well as the results of static magnetic measurements show that at room temperature all the investigated samples contain ε-Fe2O3 particles that exhibit the superparamagnetic behavior. It was established that the magnetic properties of nanoparticles significantly change with a decrease in their size to ∼6 nm. According to high-resolution electron microscopy and Mossbauer spectroscopy data, the particle structure can be attributed to the ε-modification of trivalent iron oxide; meanwhile, the temperature of the magnetic order onset in these particles is increased, the well-known magnetic transition in the range of 80-150 K does not occur, the crystallographic magnetic anisotropy constant is significantly reduced, and the surface magnetic anisotropy plays a decisive role. This is apparently due to redistribution of cations over crystallographic positions with decreasing particle size, which was established using Mössbauer spectra. As the particle size is decreased and the fraction of surface atoms is increased, the contribution of an additional magnetic subsystem formed in a shell of particles smaller than ∼4 nm becomes significant, which manifests itself in the static magnetic measurements as paramagnetic contribution. © 2015 AIP Publishing LLC.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Krasikov A. A., Dubrovskiy A. A., Semenov S. V., Popkov S. I., Stolyar S. V., Iskhakov R. S., Ladygina V. P., Yaroslavtsev R. N.
Заглавие : Specific features of magnetic properties of ferrihydrite nanoparticles of bacterial origin: A shift of the hysteresis loop
Место публикации : Phys. Solid State: MAIK Nauka-Interperiodica / Springer, 2016. - Vol. 58, Is. 2. - P.287-292. - ISSN 10637834 (ISSN), DOI 10.1134/S1063783416020050
Примечания : Cited References: 23. - This study was supported by the Ministry of Education and Science of the Russian Federation within the state contract for 2014-2016.
Предметные рубрики: Exchange bias
NiO nanoparticles
Anomalies
Аннотация: The results of the experimental investigation into the magnetic hysteresis of systems of superparamagnetic ferrihydrite nanoparticles of bacterial origin have been presented. The hysteresis properties of these objects are determined by the presence of an uncompensated magnetic moment in antiferromagnetic nanoparticles. It has been revealed that, under the conditions of cooling in an external magnetic field, there is a shift of the hysteresis loop with respect to the origin of the coordinates. These features are associated with the exchange coupling of the uncompensated magnetic moment and the antiferromagnetic “core” of the particles, as well as with processes similar to those responsible for the behavior of minor hysteresis loops due to strong local anisotropy fields of the ferrihydrite nanoparticles. © 2016, Pleiades Publishing, Ltd.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Krasikov A. A., Dubrovskiy A. A., Popkov S. I., Stolyar S. V., Bayukov O. A., Iskhakov R. S., Ladygina V. P., Yaroslavtsev R. N.
Заглавие : Magnetic properties of heat treated bacterial ferrihydrite nanoparticles
Место публикации : J. Magn. Magn. Mater.: Elsevier, 2016. - Vol. 410. - P.171-180. - ISSN 03048853 (ISSN), DOI 10.1016/j.jmmm.2016.02.059
Примечания : Cited References: 66. - TEM studies were performed on facility of Resource Sharing Center of Krasnoyarsk Scientific Center of Siberian Branch of Russian Academy of Sciences. Authors acknowledge to M.N. Volochaev for the TEM measurements.
Предметные рубрики: Hematite nanoparticles
NiO nanoparticles
Porous-glass
Ferritin
Particles
Temperature
Hysteresis
Transition
Anomalies
Mossbauer
Ключевые слова (''Своб.индексиров.''): ferrihydrite--nanoparticles--superparamagnetism
Аннотация: The magnetic properties of ferrihydrite nanoparticles, which are products of vital functions of Klebsiella oxitoca bacteria, have been studied. The initial powder containing the nanoparticles in an organic shell was subjected to low-temperature (T=160 °C) heat treatment for up to 240 h. The bacterial ferrihydrite particles exhibit a superparamagnetic behavior. Their characteristic blocking temperature increases from 26 to 80 K with the heat treatment. Analysis of the magnetization curves with regard to the magnetic moment distribution function and antiferromagnetic contribution shows that the low-temperature heat treatment enhances the average magnetic moment of a particle; i.e., the nanoparticles coarsen, probably due to their partial agglomeration during heat treatment. It was established that the blocking temperature nonlinearly depends on the particle volume. Therefore, a model was proposed that takes into account both the bulk and surface magnetic anisotropy. Using this model, the bulk and surface magnetic anisotropy constants KV≈1.7×105 erg/cm3 and KS≈0.055 erg/cm2 have been determined. The effect of the surface magnetic anisotropy of ferrihydrite nanoparticles on the observed magnetic hysteresis loops is discussed.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Балаев, Дмитрий Александрович, Красиков, Александр Александрович, Дубровский, Андрей Александрович, Семенов, Сергей Васильевич, Попков, Сергей Иванович, Столяр, Сергей Викторович, Исхаков, Рауф Садыкович, Ладыгина В. П., Ярославцев, Роман Николаевич
Заглавие : Особенности магнитных свойств наночастиц ферригидрита бактериального происхождения: смещение петли гистерезиса
Место публикации : Физ. тверд. тела: Физико-технический институт им. А. Ф. Иоффе РАН, 2016. - Т. 58, Вып. 2. - С. 280-284. - ISSN 0367-3294
Примечания : Библиогр.: 23. - Работа выполнена в рамках государственного задания Министерства образования и науки РФ на 2014-2016 гг.
Аннотация: Представлены результаты экспериментального исследования магнитного гистерезиса систем суперпарамагнитных наночастиц ферригидрита бактериального происхождения. Гистерезисные свойства определяются наличием нескомпенсированного магнитного момента в антиферромагнитных наноразмерных частицах. При условиях охлаждения во внешнем поле наблюдается смещение петли гистерезиса относительно начала координат. Указанные особенности являются следствием как обменной связи нескомпенсированного магнитного момента и антиферромагнитного ядра" частиц, а также вызваны процессами, аналогичными поведению частных петель гистерезиса, обусловленными большими величинами значений локальных полей анизотропии наночастиц ферригидрита.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Popkov S. I., Semenov S. V., Bykov A. A., Sabitova E. I., Dubrovskiy A. A., Shaikhutdinov K. A., Petrov M. I.
Заглавие : Contributions from Inter-grain Boundaries to the Magneto-resistive Effect in Polycrystalline High-T (C) Superconductors. The Underlying Reason of Different Behavior for YBCO and BSCCO Systems
Разночтения заглавия :авие SCOPUS: Contributions from inter-grain boundaries to the magneto-resistive effect in polycrystalline high-TC superconductors. the underlying reason of different behavior for YBCO and BSCCO systems
Место публикации : J. Supercond. Nov. Magn: SPRINGER, 2011. - Vol. 24, Is. 7. - P2129-2136. - ISSN 1557-1939, DOI 10.1007/s10948-011-1166-9
Примечания : Cited References: 30. - This work is supported by program N5 of RAS, project N7.
Предметные рубрики: HIGH-TEMPERATURE SUPERCONDUCTORS
PHASE-SLIP
TRANSPORT-PROPERTIES
TRANSITION
FIELD
COMPOSITES
BULK
TAPES
YBA2CU3O7-DELTA
DISSIPATION
Ключевые слова (''Своб.индексиров.''): bscco--ybco--intergrain boundaries--magnetoresistance--bscco--intergrain boundaries--magnetoresistance--ybco--bscco--bscco system--comparative studies--high tc superconductors--high-field--inter-grain--irreversibility lines--magneto-resistive effect--polycrystalline--resistive transition--standard measurements--weak pinning--ybco--bismuth--electric resistance--grain boundaries--high temperature superconductors--lead--magnetic fields--magnetoelectronics--magnetoresistance--magnetos--superconductivity--yttrium barium copper oxides--semiconductor metal boundaries
Аннотация: In order to clarify the mechanisms in charge of broadening of resistive transition R(T) in magnetic fields of bismuth-based polycrystalline high-T (C) superconductor (HTSC), a comparative study of Bi1.8Pb0.3Sr1.9Ca2Cu3O (x) (BSCCO) and YBa2Cu3O7-delta (YBCO) have been performed. Magnetoresistive effects and irreversibility line obtained from magnetic measurements have been studied. It was established that (1) for YBCO, the smooth part of R(T) dependence unambiguously corresponds to dissipation in the intergrain boundaries for arbitrary magnetic fields; (2) for polycrystalline BSCCO, the smooth part of R(T) dependences correspond to dissipation within intergrain boundary subsystem in the field range H 10(2) Oe only, while standard measurements of R(T) dependences in magnetic field range H 10(2) Oe reflect the dissipation processes occurring both in intergrain boundary and HTSC grain subsystems; (3) for the high-field range, the contribution from intergrain boundaries of BSCCO can be distinguished from magnetoresistance R(H) dependences obtained at high enough current density on textured samples. It is proposed that various magneto-resistive properties of these classical HTSC systems are due comparatively weak pinning in BSCCO.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shaykhutdinov K. A., Balaev D. A., Semenov S. V., Popkov S. I., Dubrovskiy A. A., Sapronova N. V., Volkov N. V.
Заглавие : Relaxation of low-temperature magnetoresistance and magnetization of polycrystalline (La0.5Eu0.5)(0.7)Pb0.3MnO3
Разночтения заглавия :авие SCOPUS: Relaxation of low-temperature magnetoresistance and magnetization of polycrystalline (La 0.5Eu 0.5) 0.7Pb 0.3MnO 3
Место публикации : J. Phys. D. - 2011. - Vol. 44, Is. 25. - Ст.255001. - ISSN 0022-3727, DOI 10.1088/0022-3727/44/25/255001
Примечания : Cited References: 34. - This work was partially supported by the Lavrentyev Competition of the Young Scientist's Projects of the Siberian Branch of the Russian Academy of Sciences, Project No 12. The authors are grateful to A D Balaev and V M Sosnin for useful discussions on the results.
Предметные рубрики: INSULATOR-METAL TRANSITION
GRANULAR FILMS
NANOPARTICLES
PR0.7CA0.3MNO3
PERCOLATION
MANGANITES
Ключевые слова (''Своб.индексиров.''): antiferromagnetic boundaries--characteristic value--ferromagnetic domains--ferromagnetic metal--lanthanum manganites--logarithmic law--low temperatures--magneto-resistive effect--polycrystalline--relative orientation--relaxation of magnetization--temperature fluctuation--time evolutions--time interval--tunnel magnetoresistance--antiferromagnetism--electric resistance--europium--ferromagnetic materials--ferromagnetism--grain boundaries--grain size and shape--lanthanum compounds--lead--magnetic domains--magnetic moments--magnetoelectronics--magnetoresistance--manganese oxide--magnetization
Аннотация: Hysteresis and relaxation of magnetoresistance and magnetization of substituted (La0.5Eu0.5)(0.7)Pb0.3MnO3 lanthanum manganite in a low-temperature region ( 40 K) are investigated. It is shown that at these temperature features of the magnetoresistive effect are determined mainly by spin-dependent tunnelling of carriers via insulating grain boundaries. As was demonstrated previously, the grain boundaries may be antiferromagnetically ordered. Therefore, relaxation of magnetization and resistance is determined by the processes of relative orientation of the magnetic moments of ferromagnetic domains neighbouring the antiferromagnetic boundary of ferromagnetic domains under the action of temperature fluctuations. It is shown that relaxation follows the logarithmic law within the time interval t similar to 10(2)-3x10(3) s. A comparison between time evolutions of the magnetic moment and resistance shows that magnetoresistance and magnetization are related as delta R
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12.

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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13.

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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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shaykhutdinov K. A., Popkov S. I., Balaev D. A., Semenov S. V., Bykov A. A., Dubrovskiy A. A., Sapronova N. V., Volkov N. V.
Заглавие : Non-linear current-voltage characteristics of (La0.5Eu0.5)(0.7)Pb0.3MnO3 single crystals: Possible manifestation of the internal heating of charge carriers
Коллективы :
Разночтения заглавия :авие SCOPUS: Non-linear currentvoltage characteristics of (La0.5Eu 0.5)0.7Pb0.3MnO3 single crystals: Possible manifestation of the internal heating of chargecarriers
Место публикации : Physica B: ELSEVIER SCIENCE BV, 2010. - Vol. 405, Is. 24. - P4961-4965. - ISSN 0921-4526, DOI 10.1016/j.physb.2010.09.043
Примечания : Cited References: 19. - The authors are grateful to A.N. Lavrov for useful discussions on the results. This study was partially supported by the Russian Foundation for Basic Research, Project no. 08-02-00259a and the Lavrent'ev Young Scientists' Competition of the Siberian Branch of the Russian Academy of Sciences. Project no. 12.
Предметные рубрики: INSULATOR-METAL TRANSITION
PR0.7CA0.3MNO3
MANGANITES
Ключевые слова (''Своб.индексиров.''): manganites--negative differential resistance--cvc--cvc--manganites--negative differential resistance--applied electric field--charge ordering--current switching--cvc--dielectric regions--experimental data--internal heating--lanthanum manganites--metal-dielectric transition--negative differential resistances--non equilibrium--non-linear--sample heating--temperature evolution--transport currents--electric fields--electron gas--europium--heating--lanthanum--lead--manganites--negative resistance--phase separation--single crystals--thermal conductivity--manganese oxide
Аннотация: Temperature evolution of the current-voltage characteristics (CVCs) of a single-crystal lanthanum manganite (La0.5Eu0.5)(0.7)Pb0.3MnO3 is investigated in a wide (up to 1 A) range of instrumental currents. Effects of a transport current and an applied electric field on the resistance of the material are studied in view of possible implementation of the charge ordering break in dielectric regions occurring due to phase separation in manganites. A negative differential resistance portion observed in the CVCs suggests the presence of a current switching effect. Below the temperature of the metal-dielectric transition in (La0.5Eu0.5)(0.7)Pb0.3MnO3, the hysteresis is observed in the CVC. The detailed analysis of the internal sample heating on the basis of experimental data on thermal conductivity showed, however, that these CVC features can be explained within the concept of non-equilibrium heating of electron gas. (C) 2010 Elsevier B.V. All rights reserved.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Dubrovskiy A. A., Popkov S. I., Shaikhutdinov K. A., Mart'yanov O. N., Petrov M. I.
Заглавие : Nonmonotonic Behavior of Magnetoresistance, R(H) Hysteresis, and Low-Temperature Heat Capacity of the BaPb0.75Bi0.25O3 Superconductor in a Magnetic Field: Possible Manifestations of Phase Separation
Коллективы :
Разночтения заглавия :авие SCOPUS: Nonmonotonic behavior of magnetoresistance, R(H) hysteresis, and low-temperature heat capacity of the BaPb0.75Bi0.25O 3 superconductor in a magnetic field: Possible manifestations of phase separation
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2010. - Vol. 110, Is. 4. - P584-593. - ISSN 1063-7761, DOI 10.1134/S1063776110040059
Примечания : Cited References: 27. - This study was performed under the program no. 5 of the Russian Academy of Sciences (project no. 7).
Предметные рубрики: ELECTRONIC SPECIFIC-HEAT
BAPB1-XBIXO3 SYSTEM
YBA2CU3O7-DELTA
COMPOSITES
TRANSITION
HTSCS
300-K
Ключевые слова (''Своб.индексиров.''): diamagnetic response--effective field--heat capacities--high-t--hysteretic dependence--josephson--low temperature heat capacities--non-monotonic dependence--nonmonotonic behaviors--polycrystalline--spatially inhomogeneous--transport currents--electric resistance--hysteresis--magnetic field effects--magnetic flux--magnetoelectronics--magnetoresistance--phase separation--semiconductor metal boundaries--specific heat--superconducting magnets--superconducting materials--superconductivity--transport properties--magnetic materials
Аннотация: The transport properties (R(T) and R(H) dependences at various values of the transport current in magnetic fields up to 65 kOe) and low-temperature heat capacity in magnetic fields up to 90 kOe of the BaPb0.75Bi0.25O3 superconductor (T-C approximate to 11.3 K) are investigated with the goal of clarifying the mechanisms determining the nonmonotonic behavior and hysteresis of its magnetoresistance R(H). The type of R(H) hysteretic dependences for BaPb0.75Bi0.25O3 is analogous to that observed in granular high-T-c superconductors (HTSCs); however, unlike classical HTSC systems, the field width of the magnetoresistance hysteresis loop for polycrystalline BaPb0.75Bi0.25O3 depends on the transport current. This means that although the mechanisms responsible for the magnetoresistance hysteresis (the influence of the magnetic flux trapped in super-conducting regions on the effective field in Josephson interlayers) are identical in these objects, the transport current in BaPb0.75Bi0.25O3 may considerably affect the diamagnetic response of the superconductor. A considerable effect of transport current on the field in which the R(H) dependences have a peak and exhibit hysterestic properties is observed. Such a behavior can be adequately interpreted using the model of the spatially inhomogeneous superconductor-insulator state proposed by Gorbatsevich et al. [JETP Lett. 52, 95 (1990)]. The nonmonotonic dependence of quantity C/T (C is the heat capacity) on the magnetic field discovered in the present study also agrees with the conclusions based on this model.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Dubrovskiy A. A., Shaykhutdinov K. A., Popkov S. I., Petrov M. I.
Заглавие : Peculiarities of the time evolution of magnetoresistance of granular HTSC in a constant applied magnetic field
Коллективы :
Место публикации : Solid State Commun. - 2008. - Vol. 147, Is. 7-8. - P.284-287. - ISSN 0038-1098, DOI 10.1016/j.ssc.2008.05.044
Примечания : Cited References: 17. - This work was Supported by program "Quantum macrophysics" No. 3.4 of RAS and integration project No. 3.4 of SB RAS and in part by KSF, grant 18G011. D.A.B. and A.A.D. acknowledge the Russian Science Support Foundation.
Предметные рубрики: CRITICAL-STATE
SUPERCONDUCTORS
COMPOSITES
HYSTERESIS
RESISTANCE
Ключевые слова (''Своб.индексиров.''): superconductors--flux pinning and creep--tunneling--superconductors--flux pinning and creep--tunneling--agricultural products--carbon fiber reinforced plastics--copper oxides--electric conductivity--electric resistance--evolutionary algorithms--ferromagnetism--galvanomagnetic effects--grain (agricultural product)--health--hysteresis--magnetic devices--magnetic field effects--magnetic field measurement--magnetic fields--magnetic materials--magnetoelectronics--magnetoresistance--semiconductor metal boundaries--superconducting magnets--superconductivity--yttrium barium copper oxides--p ,p ,t measurements--applied (co)--applied magnetic fields--constant magnetic field (cmf)--elsevier (co)--evolution (co)--external fields--field induced--flux creep--hysteretic behavior--josephson couplings--low magnetic fields--magnetic (ce)--poly crystalline--superconducting grains--time evolutions--time relaxation--magnetism
Аннотация: The time evolution of the magnetoresistance of bulk YBCO + CuO composites at T = 4.2 K in constant applied magnetic fields was studied to clarify the mechanism of hysteretic behavior of magnetoresistance R(H) of granular HTSC. The composites represent "model" granular HTSC with weakened Josephson coupling between superconducting (YBCO) crystallites. It was found for the first time that on the ascending branch of R(H) dependence, the resistance at H = const decreased with time while on the descending branch, the resistance increased with time in ail applied constant magnetic field. In the range of low magnetic fields (below the minimum point of the descending branch of the R(H) dependence), the resistance at H const decreased again. Similar measurements performed oil pure polycrystalline YBCO at T = 77.4 K have shown that the behavior of evolution of resistance with time is similar to that observed for the composite. This proves the peculiarity of time evolution of maignetoresistance to be a common feature of granular HTSCs. The behavior revealed is well described by the model Of granular HTSC, where the intergrain media is in an effective magnetic field which is the superposition of the external field and the field induced by superconducting grains. The time evolution of resistance reflects the time relaxation of magnetization of HTSC grains due to the intragrain flux Creep Processes. (C) 2008 Elsevier Ltd. All rights reserved.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Dubrovskiy A. A., Popkov S. I., Shaykhutdinov K. A., Petrov M. I.
Заглавие : Magnetic field dependence of intergrain pinning potential in bulk granular composites YBCO plus CuO demonstrating large magneto-resistive effect
Разночтения заглавия :авие SCOPUS: Magnetic field dependence of intergrain pinning potential in bulk granular composites YBCO + CuO demonstrating large magneto-resistive effect
Место публикации : J. Supercond. Nov. Magn.: SPRINGER, 2008. - Vol. 21, Is. 4. - P243-247. - ISSN 1557-1939, DOI 10.1007/s10948-008-0324-1
Примечания : Cited References: 22
Предметные рубрики: HIGH-TEMPERATURE SUPERCONDUCTORS
ACTIVATED PHASE-SLIP
TRANSITION
DISSIPATION
MECHANISM
SENSORS
MODEL
Ключевые слова (''Своб.индексиров.''): bulk granular high-t(c) superconductor--magneto-resistive effect--josephson junction network--inter-grain pinning potential--bulk granular high-t c superconductor--inter-grain pinning potential--josephson junction network--magneto-resistive effect--bulk composites--bulk granular high-t subc/sub superconductor--granular composites--inter-grain pinning potential--josephson junction network--magnetic field dependences--magneto-resistive effect--pinning potential--resistive effects--resistive transitions--wide temperature range--y-ba-cu-o--atmospheric temperature--barium--copper--copper oxides--electric resistance--magnetic field measurement--magnetic fields--magnetoresistance--magnetos--yttrium barium copper oxides--magnetic field effects
Аннотация: The broadening of the resistive transition in magnetic field and isotherms of magnetoresistance of bulk composites Y-Ba-Cu-O + CuO have been studied. These composites exhibit large magneto-resistive effect in a wide temperature range below T (C) due to weakening of Josephson coupling in this system. The broadening of the resistive transition and magnetoresistance are explained well by the Ambegaokar-Halperin (AH) model for phase slip in Josephson junctions. The magnetic field dependence of pinning potential in the intergrain boundaries deduced from AH model found out to be similar to that of critical current of an array of Josephson junctions. The values of pinning energy point out that the large magneto-resistive effect observed in the composites results from flux flow-like processes at the intergrain boundaries.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Petrov M. I., Balaev D. A., Gokhfeld Yu. S., Dubrovskiy A. A., Shaykhutdinov K. A.
Заглавие : Enhancement of pinning in cerium doped Y(1-x)CexBa2Cu3O7HTSC
Разночтения заглавия :авие SCOPUS: Enhancement of pinning in cerium doped Y(1-x)CexBa2Cu3O7 HTSC
Место публикации : Physica C: ELSEVIER SCIENCE BV, 2007. - Vol. 460: 8th International Conference on Materials and Mechanisms of Superconductivity and High Temperature Superconductors (JUL 09-14, 2006, Dresden, GERMANY). - P1192-1193. - ISSN 0921-4534, DOI 10.1016/j.physc.2007.04.046
Примечания : Cited References: 2
Ключевые слова (''Своб.индексиров.''): htsc--ybco--ce doped--flux pinning--ce doped--flux pinning--htsc--ybco--cerium--doping (additives)--flux pinning--lattice constants--magnetization--yttrium compounds--cerium ions--diamagnetic responses--temperature dependence--high temperature superconductors
Аннотация: To test the pinning force in high-temperature superconductors with minor doping, the Y(1-x)CexBa2Cu3O7 system has been synthesized. Temperature dependence of magnetization has been determined. The difference of diamagnetic responses M(zfc) - M(fc) is non-monotonic. It has a peak at a concentration value x = 0.0156, which corresponds to the most probable distance between cerium ions equal to eight lattice constants in the a-b plane and close to the diameter of vortices. (c) 2007 Elsevier B.V. All rights reserved.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Dubrovskiy A. A., Shaykhutdinov K. A., Popkov S. I., Petrov M. I.
Заглавие : Time relaxation of residual resistance of HTSC-based composites
Место публикации : Physica C: ELSEVIER SCIENCE BV, 2007. - Vol. 460: 8th International Conference on Materials and Mechanisms of Superconductivity and High Temperature Superconductors (JUL 09-14, 2006, Dresden, GERMANY). - P1309-1310. - ISSN 0921-4534, DOI 10.1016/j.physc.2007.03.347
Примечания : Cited References: 5
Предметные рубрики: SUPERCONDUCTORS
Ключевые слова (''Своб.индексиров.''): granular htsc--resistance--relaxation--magnetic flux--granular htsc--magnetic flux--relaxation--resistance--copper oxides--crystallites--magnetic flux--magnetic relaxation--magnetization--yttrium barium copper oxides--anderson-like relaxation processes--flux trapping--residual resistance--time relaxation--josephson junction devices
Аннотация: Magnetoresistance curves R(H) and time relaxation of the residual resistance of bulk YBCO + CuO composites have been studied. These composites represent the network of Josephson junctions, where CuO acts as a barrier between YBCO grains. It has been shown that hysteresis of the R(H) dependences is related to the flux trapping within the YBCO crystallites. This flux induces magnetic field in the intergrain media. Time relaxation of the residual resistance is caused by relaxation of the magnetization of YBCO grains. The time dependence of the residual resistance obeys a logarithmic law, which describes the Anderson-like relaxation processes in the YBCO grains. (c) 2007 Elsevier B.V. All rights reserved.
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20.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Shaikhutdinov K. A., Terent'yev K. Yu., Petrov M. I., Dubrovskiy A. A., Pavlovskii M. S., Lavrov A. N.
Заглавие : The magnetostriction effect in the bilayered manganites single crystals
Коллективы : Euro-Asian Symposium "Trends in MAGnetism", "Trends in MAGnetism", Euro-Asian Symposium, Институт физики им. Л.В. Киренского Сибирского отделения РАН
Место публикации : VI Euro-Asian Symposium "Trends in MAGnetism" (EASTMAG-2016): abstracts/ ed.: O. A. Maksimova, R. D. Ivantsov. - Krasnoyarsk: KIP RAS SB, 2016. - Ст.O1.4. - P.40. - ISBN 978-5-904603-06-9 (Шифр -478014040)
Примечания : References: 3
Ключевые слова (''Своб.индексиров.''): keywords:magnetostriction--chemical pressure--methamagnetic transition--chemical substitution
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