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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Boldyrev K. N., Pisarev R. V., Bezmaternykh L. N., Popova M. N.
Заглавие : Antiferromagnetic dichroism in a complex multisublattice magnetoelectric CuB2O4
Коллективы : Russian Academy of Sciences under the Programs for Basic Research; Russian Federation [MK-3521.2015.2], Russian Foundation for Basic Research [15-32-20613, 15-02-04222], Ministry of Education and Science of the Russian Federation [14.B25.0031.25]
Место публикации : Phys. Rev. Lett.: American Physical Society, 2015. - Vol. 114, Is. 24. - Ст.247210. - ISSN 0031, DOI 10.1103/PhysRevLett.114.247210. - ISSN 10797114(eISSN)
Примечания : Cited References:40. - This study was supported by the Russian Academy of Sciences under the Programs for Basic Research, by the President of the Russian Federation (Grant No. MK-3521.2015.2, K. N. B.), by the Russian Foundation for Basic Research (Grants No. 15-32-20613, K. N. B., and No. 15-02-04222, R. V. P.), and by the Ministry of Education and Science of the Russian Federation (Grant No. 14.B25.0031.25, R. V. P.).
Предметные рубрики: MAGNETIC SOLITON LATTICE
COPPER METABORATE
GYROTROPIC BIREFRINGENCE
SPECTROSCOPY
EXCITATIONS
TRANSITIONS
CRYSTALS
Cr2O3
FIELD
Аннотация: Magnetic control of the crystal chirality was announced by Saito et al. [Phys. Rev. Lett. 101, (2008)] on the ground of experiments in CuB2O4. This claim has raised a sharp dispute in the literature because it seemed to contradict the fundamental symmetry principles. We settle this dispute on the basis of a high-resolution optical spectroscopy study of excitonic transitions in CuB2O4. We find that a large sublattice-sensitive antiferromagnetic linear dichroism (LD) emerges at the Néel temperature TN=21 K and show how it could simulate a “magnetic-field control of the crystal chirality.” We prove that the discovered LD is related microscopically to the magnetic Davydov splitting. This LD is highly sensitive to subtle changes in the spin subsystems, which allowed us to observe a splitting of the phase transition into an incommensurate magnetic phase into two transitions (T∗1=8.5 and T∗2=7.9 K) and to suggest elliptical spiral structures below T∗1, instead of a simple circular helix proposed earlier.О магнитном контроле кристаллической хиральности сообщил Сайто и др. [Phys. Rev. Lett. 101, 117402 (2008)] на основании экспериментов в CuB2O4. Это требование вызвало резкий спор в литературе, потому что это казалось, противоречат основным принципам симметрии. Мы урегулировать этот спор на основе исследования с помощью оптической спектроскопии высокого разрешения экситонных переходов в CuB2O4. Мы считаем, что большой подрешетко-чувствительный антиферромагнитный линейный дихроизм (LD) возникает при температуре Нееля TN= 21 Kи показываем, как это может имитировать "контроль магнитным полем кристаллической хиральности." Мы докажем, что обнаруженный LD связанс микроскопическим магнитным Давыдовским расщеплением. Этот Л.Д. весьма чувствителен к тонким изменениям в спиновых подсистем, которые позволили нам наблюдать расщепление фазового перехода в несоизмеримы магнитная фаза в двух переходов (T*1= 8,5 и Т*2 = 7,9 К) и предположить эллиптическую спиральную структуру ниже T*1, вместо простой круговой спирали предложенный ранее.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Valkov V. V., Valkova T. A.
Заглавие : Application of indefinite metric for transition to bose description of Su(3) hamiltonians - excitation spectrum of spin nematics
Место публикации : Zhurnal Eksperimentalnoi Teor. Fiz. - 1991. - Vol. 99, Is. 6. - P.1881-1897. - ISSN 0044-4510
Примечания : Cited References: 37
Предметные рубрики: BIQUADRATIC EXCHANGE
PHASE-TRANSITIONS
DIAGRAM TECHNIQUE
MAGNETISM
FIELD
STATE
Аннотация: A procedure is developed for a correct transition to the Bose representation for quantum SU(3) Hamiltonians. The analysis is carried out for a spin nematic by applying the indefinite metric formalism and pseudo-Hubbard operators. An important aspect of the theory is that the finiteness of the number of physical states is taken into account. This is attained by introducing and consistently taking into account the metric operator for which purpose a simple expression in terms of Bose operators is suggested. It is shown that in this approach the quantum Bose analog of the Hamiltonian is an Hermitian operator. This circumstance removes a number of principle contradictions which appeared previously on application of the Bose analog of the Hamiltonian derived by virtually identifying the Hubbard and pseudo-Hubbard operators and ignoring the finiteness of the number of physical states. The integral equations defining the chief characteristics of the system are obtained and solved analytically for the spin-nematic state of a magnet with S = 1 and by taking into account anharmonic effects. This permits one to write down in nonlinear theory explicit expressions for the two branches of the quantum excitation spectrum. The character of the renormalization of the spectrum parameters due to the presence of zero-point quantum oscillations is studied. The renormalization of the critical field on transition of the system from the spin nematic state is calculated analytically.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Volkov N. V., Tarasov A. S., Smolyakov D. A., Varnakov S. N., Ovchinnikov S. G.
Заглавие : Bias-voltage-controlled ac and dc magnetotransport phenomena in hybrid structures
Коллективы : Moscow International Symposium on Magnetism , Russian Foundation for Basic Research [14-02-00234-a, 14-02-31156], Presidium of the Russian Academy of Sciences [20.8], Ministry of Education and Science of the Russian Federation [02.G25.31.0043]
Место публикации : J. Magn. Magn. Mater./ Moscow International Symposium on Magnetism (6th ; Moscow) (29 June – 3 July 2014): Elsevier Science, 2015. - Vol. 383. - P.69-72. - ISSN 0304-8853, DOI 10.1016/j.jmmm.2014.11.014
Примечания : Cited References:15. - This study was supported by the Russian Foundation for Basic Research, Projects nos. 14-02-00234-a and 14-02-31156, the Presidium of the Russian Academy of Sciences, Program Quantum Mesoscopic and Disordered Structures, Project no. 20.8 and the Ministry of Education and Science of the Russian Federation, Project no. 02.G25.31.0043.
Предметные рубрики: SILICON
SPINTRONICS
FIELD
Ключевые слова (''Своб.индексиров.''): spintronics--hybrid structures--magnetoresistance--magnetoimpedance--photoinduced magnetoresistance
Аннотация: We report some ac and dc magnetotransport phenomena in silicon-based hybrid structures. The giant impedance change under an applied magnetic field has been experimentally found in the metal/insulator/semiconductor (MIS) diode with the Schottky barrier based on the Fe/SiO2/p-Si and Fe/SiO2/n-Si structures. The maximum effect is found to observe at temperatures of 10-30 K in the frequency range 10 Hz-1 MHz, Below 1 kHz the magnetoresistance can be controlled in a wide range by applying a bias to the device. A photoinduced dc magnetoresistance of over 104% has been found in the Fe/SiO2/p-Si back-to-back Schottky diode. The observed magnetic-field-dependent effects are caused by the interface states localized in the insula-tor/semiconductor interface. (C) 2014 Elsevier B.V. All rights reserved.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Popkov S. I., Sabitova E. I., Semenov S. V., Shaykhutdinov K. A., Shabanov A. V., Petrov M. I.
Заглавие : Compression of a magnetic flux in the intergrain medium of a YBa2Cu3O7 granular superconductor from magnetic and magnetoresistive measurements
Разночтения заглавия :авие SCOPUS: Compression of a magnetic flux in the intergrain medium of a YBa 2Cu 3O 7 granular superconductor from magnetic and magnetoresistive measurements
Место публикации : J. Appl. Phys.: AMER INST PHYSICS, 2011. - Vol. 110, Is. 9. - Ст.93918. - ISSN 0021-8979, DOI 10.1063/1.3657775
Примечания : Cited References: 21. - We thank V. V. Val'kov and A. D. Balaev for useful discussions of the results and I. Nemtsev for microscopic study of the samples. The study was supported by the Program of the Russian Academy of Sciences No. 5, Project No. 7.
Предметные рубрики: HIGH-TEMPERATURE SUPERCONDUCTORS
CRITICAL-CURRENT-DENSITY
CRITICAL-STATE MODEL
CRITICAL CURRENTS
JOSEPHSON MEDIUM
FIELD
TRANSITION
Ключевые слова (''Своб.индексиров.''): effective field--external fields--field dependence--field induced--granular superconductors--inter-grain--josephson--magnetoresistive--space between--superconducting grains--transport currents--electric resistance--magnetic flux--magnetic moments--superconductivity--superconducting materials
Аннотация: A method to determine a value of the effective field in the intergrain medium of a granular superconductor is proposed. The space between superconducting grains is considered to be a Josephson medium where passage of the transport current causes dissipation and the effective field is superposition of external field H and the field induced by magnetic moments of superconducting grains. The method proposed is based on the comparison of hysteresis field dependences of magnetoresistance and magnetization and their relaxation at H=const. By the example of granular YBa2Cu3O7, it is shown that, in the region of weak fields, the effective field in the intergrain medium exceeds by far the external field, i.e., compression of a magnetic flux occurs. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3657775]
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Pervushin V. N., Arbuzov A. B., Barbashov B. M., Nazmitdinov R. G., Borowiec A., Pichugin K. N., Zakharov A. F.
Заглавие : Conformal and affine Hamiltonian dynamics of general relativity
Место публикации : Gen. Relativ. Gravit.: Springer/Plenum Publishers, 2012. - Vol. 44, Is. 11. - P.2745-2783. - ISSN 0001-7701, DOI 10.1007/s10714-012-1423-7
Примечания : Cited References: 76. - The authors would like thank M. Bordag, S. Deser, D. Ebert, A. Efremov, V. Gershun, Yu. Ignatev, E. Lukierski, and A. Zheltukhin for useful discussions. VNP and AB were supported in part by the Bogoliubov-Infeld program. AFZ is grateful to the JINR Directorate for a support.
Предметные рубрики: COSMOLOGICAL PERTURBATIONS
ACCELERATING UNIVERSE
STANDARD MODEL
SUPERNOVAE
GRAVITATION
FIELD
IA
REPRESENTATIONS
SYMMETRIES
OPERATORS
Ключевые слова (''Своб.индексиров.''): conformal cosmology--general relativity--hamiltonian dynamics--casimir energy
Аннотация: The Hamiltonian approach to the General Relativity is formulated as a joint nonlinear realization of conformal and affine symmetries by means of the Dirac scalar dilaton and the Maurer-Cartan forms. The dominance of the Casimir vacuum energy of physical fields provides a good description of the type Ia supernova luminosity distance-redshift relation. Introducing the uncertainty principle at the Planck's epoch within our model, we obtain the hierarchy of the Universe energy scales, which is supported by the observational data. We found that the invariance of the Maurer-Cartan forms with respect to the general coordinate transformation yields a single-component strong gravitational waves. The Hamiltonian dynamics of the model describes the effect of an intensive vacuum creation of gravitons and the minimal coupling scalar (Higgs) bosons in the Early Universe.
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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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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aver'yanov E. M.
Заглавие : Correlation of the molecular structure of discotic nematic liquid crystals with their orientational order and specific features of the nematic-isotropic phase transition
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2004. - Vol. 46, Is. 8. - P1554-1559. - ISSN 1063-7834, DOI 10.1134/1.1788794
Примечания : Cited References: 32
Предметные рубрики: MONTE-CARLO
ANISOTROPIC SYSTEMS
COMPUTER-SIMULATION
BEHAVIOR
TRIPHENYLENE
DISCOGEN
MESOGEN
FIELD
Аннотация: The orientational order parameter S of molecules in high-temperature discotic nematic liquid-crystal phases of triphenylene derivatives is investigated as a function of the length of side flexible molecular chains at different temperatures. It is established that the orientational order parameters S in the range of the transition from the nematic phase to the isotropic liquid phase (the N-D-I transition) are smaller than those predicted from the molecular-statistical theory and computer simulation. It is shown that the N-D-I transition is close to both the isolated Landau point and the tricritical point (regardless of the chemical structure of the molecules and the anisotropy of dispersion intermolecular interactions). Consistent explanations are offered for a number of experimental findings, such as the anomalously small changes in the enthalpy and entropy upon the N-D-I transition (as compared to those revealed upon the N-I transition in calamitic nematic liquid crystals), the anomalously strong response of the isotropic phase of discotic nematic liquid crystals to external fields (thermodynamically conjugate to the order parameter S) and the long relaxation times of this response, and the formation of cybotactic discotic molecular clusters in the isotropic phase in the vicinity of the N-D-I transition. (C) 2004 MAIK "Nauka / Interperiodica".
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Plotkin V. V., Dyad'kov P. G., Ovchinnikov S. G.
Заглавие : Detecting a magnesiowustite phase transition in the lower mantle by inversion of geomagnetic data
Коллективы : Siberian Branch of the Russian Academy of Sciences [96]
Место публикации : Russ. Geol. Geophys.: Elsevier Science, 2014. - Vol. 55, Is. 9. - P.1138-1145. - ISSN 1068-7971, DOI 10.1016/j.rgg.2014.08.009. - ISSN 1878-030X
Примечания : Cited References: 26. - The study was supported by the Siberian Branch of the Russian Academy of Sciences (interdisciplinary integration project no. 96).
Предметные рубрики: ELECTRICAL-CONDUCTIVITY
SATELLITE MEASUREMENTS
EARTHS MANTLE
GLOBAL MVS
INDUCTION
FIELD
METALLIZATION
Ключевые слова (''Своб.индексиров.''): magnesiowustite--metallic state--phase transition--lower mantle--conductivity--geomagnetic variations--global network
Аннотация: Global geomagnetic data are inverted for detecting a high-conductivity layer at depths of 1500-2000 km to test the hypothesis of a magnesiowustite phase transition in the lower mantle. We present the results of processing of both synthetic and global data-average monthly values of the geomagnetic field from 1920 to 2009. The inverted global data are consistent with the possible existence of a high-conductivity layer at great depths in the lower mantle.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Alekseev K. N., Erementchouk M. V., Kusmartsev F. V.
Заглавие : Direct-current generation due to wave mixing in semiconductors
Место публикации : Europhys. Lett. - 1999. - Vol. 47, Is. 5. - P.595-600. - ISSN 0295-5075, DOI 10.1209/epl/i1999-00430-0
Примечания : Cited References: 34
Предметные рубрики: BLOCH OSCILLATOR
SUPERLATTICES
PHOTOCURRENT
TRANSPORT
FREQUENCY
FIELD
RECTIFIERS
EMISSION
CHAOS
GAAS
Аннотация: We describe an effect of the generation of direct current which may arise in semiconductors or semiconductor microstructures due to a mixing of coherent electromagnetic radiations of commensurate frequencies. The effect is, in essence, due to a nonparabolicity of the electron energy bands and is stronger in systems where this nonparabolicity is greater. We have made exact calculations in the framework of the Kane model, applicable to narrow-gap semiconductors and the tight-binding model which we employ for a description of a semiconductor superlattice.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Vyunishev A. M., Myslivets S. A., Fokin V. A., Volochaev M. N., Smolyarova T. E., Radionov N. V., Zaitsev A. I., Arkhipkin V. G., Chirkin A. S.
Заглавие : Dual wavelength Talbot self-imaging using facet patterned nonlinear crystals
Коллективы : Russian Science Foundation (RSF) [19-12-00203]
Место публикации : Opt. Lett. - 2019. - Vol. 44, Is. 15. - P.3761-3764. - ISSN 0146-9592, DOI 10.1364/OL.44.003761. - ISSN 1539-4794(eISSN)
Примечания : Cited References: 19. - Russian Science Foundation (RSF) (19-12-00203).
Предметные рубрики: RAMAN-NATH DIFFRACTION
LITHOGRAPHY
FIELD
Аннотация: A method for functional patterning of facets of a nonlinear crystal using focused ion beam milling has been developed. The near-field diffraction on periodic gratings has been experimentally and theoretically studied. The periodicity of the structure enables Talbot self-imaging at the fundamental and second-harmonic frequencies simultaneously. Spatial interference patterns for both harmonic frequencies are individual ones, which can enable the higher-accuracy optical testing, coupling the radiation at both frequencies, and wavelength-division demultiplexing. The impact of the aperture effect on a Talbot carpet is discussed.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Rudyak V. Yu., Krakhalev M. N., Sutormin V. S., Prishchepa O. O., Zyryanov V. Ya., Liu J. H., Emelyanenko A. V., Khokhlov A. R.
Заглавие : Electrically induced structure transition in nematic liquid crystal droplets with conical boundary conditions
Коллективы : Russian Science Foundation [16-43-03010]; Ministry of Science and Technology of Taiwan [MOST 105-2923-E-006-007]
Место публикации : Phys. Rev. E. - 2017. - Vol. 96, Is. 5. - Ст.052701. - ISSN 2470-0045, DOI 10.1103/PhysRevE.96.052701. - ISSN 2470-0053(eISSN)
Примечания : Cited References:36. - This study was supported by the joint project of the Russian Science Foundation (Project No. 16-43-03010) and Ministry of Science and Technology of Taiwan (Contract No. MOST 105-2923-E-006-007). The simulations have been performed using the facilities of the Lomonosov Moscow State University Research Computational Center [37].
Предметные рубрики: RIGIDLY FIXED POLES
FRIEDERICKSZ THRESHOLD
ISOTROPIC LIQUID
FIELD
Аннотация: Polymer-dispersed liquid crystal composites have been a focus of study for a long time for their unique electro-optical properties and manufacturing by "bottom-up" techniques at large scales. In this paper, nematic liquid crystal oblate droplets with conical boundary conditions (CBCs) under the action of electric field were studied by computer simulations and polarized optical microscopy. Droplets with CBCs were shown to prefer an axial-bipolar structure, which combines a pair of boojums and circular disclinations on a surface. In contrast to droplets with degenerate planar boundary conditions (PBCs), hybridization of the two structure types in droplets with CBCs leads to a two-minima energy profile, resulting in an abrupt structure transition and bistable behavior of the system. The nature of the low-energy barrier in droplets with CBCs makes it highly sensitive to external stimuli, such as electric or magnetic fields, temperature, and light. In particular, the value of the electric field of the structure reorientation in droplets with CBCs was found to be a few times smaller than the one for droplets with PBCs, and the droplet state remained stable after switching off the voltage.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Popkov S. I., Krasikov A. A., Semenov S. V., Dubrovskii A. A., Yakushkin S. S., Kirillov V. L., Mart'yanov O. N., Balaev D. A.
Заглавие : Features of the pulsed magnetization switching in a high-coercivity material based on ε-Fe2O3 nanoparticles
Коллективы : Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR); Government of the Krasnoyarsk Krai; Krasnoyarsk Territorial Foundation [18-42-240012]
Место публикации : Phys. Solid State. - 2020. - Vol. 62, Is. 3. - P.445-453. - ISSN 1063-7834, DOI 10.1134/S1063783420030166. - ISSN 1090-6460(eISSN)
Примечания : Cited References: 44. - The study was supported by the Russian Foundation for Basic Research, the Government of the Krasnoyarsk Krai, and the Krasnoyarsk Territorial Foundation for Support of Scientific and R&D Activities, project no. 18-42-240012 "Magnetization Switching of Magnetic Nanoparticles in Strong Pulsed Magnetic Fields: New Approach to Studying the Dynamic Effects Related to the Magnetization of Magnetic Nanoparticles."
Предметные рубрики: HIGH-TEMPERATURE
WAVE ABSORBER
OXIDE
FIELD
TRANSITION
RESONANCE
Аннотация: The magnetic structure of the ε-Fe2O3 iron oxide polymorphic modification is collinear ferrimagnetic in the range from room temperature to ~150 K. As the temperature decreases, ε-Fe2O3 undergoes a magnetic transition accompanied by a significant decrease in the coercivity Hc and, in the low-temperature range, the compound has a complex incommensurate magnetic structure. We experimentally investigated the dynamic magnetization switching of the ε-Fe2O3 nanoparticles with an average size of 8 nm in the temperature range of 80–300 K, which covers different types of the magnetic structure of this iron oxide. A bulk material consisting of xerogel SiO2 with the ε-Fe2O3 nanoparticles embedded in its pores was examined. The magnetic hysteresis loops under dynamic magnetization switching were measured using pulsed magnetic fields Hmax of up to 130 kOe by discharging a capacitor bank through a solenoid. The coercivity Нс upon the dynamic magnetization switching noticeably exceeds the Нс value under the quasi-static conditions. This is caused by the superparamagnetic relaxation of magnetic moments of particles upon the pulsed magnetization switching. In the range from room temperature to ~ 150 K, the external field variation rate dH/dt is the main parameter that determines the behavior of the coercivity under the dynamic magnetization switching. It is the behavior that is expected for a system of single-domain ferro- and ferrimagnetic particles. Under external conditions (at a temperature of 80 K) when the ε-Fe2O3 magnetic structure is incommensurate, the coercivity during the pulsed magnetization switching depends already on the parameter dH/dt and is determined, to a great extent, by the maximum applied field Hmax. Such a behavior atypical of systems of ferrimagnetic particles is caused already by the dynamic spin processes inside the ε-Fe2O3 particles during fast magnetization switching.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sadreev A. F.
Заглавие : Feshbach projection formalism for transmission through a time-periodic potential
Место публикации : Phys. Rev. E: American Physical Society, 2012. - Vol. 86, Is. 5. - Ст.56211. - ISSN 1539-3755, DOI 10.1103/PhysRevE.86.056211
Примечания : Cited References: 33
Предметные рубрики: NUCLEAR REACTIONS
UNIFIED THEORY
QUANTUM
FIELD
SCATTERING
SYSTEM
STATES
Аннотация: The Feshbach projection formalism is applied to consider quantum transmission through a tight-binding wire subject to a time-periodic potential. The wire is coupled with two leads via the coupling constant v(C). The periodicity of the potential implies an additional temporal dimension that reduces the problem to stationary transmission through an effectively two-dimensional lattice system. The non-Hermitian effective Hamiltonian is formulated. Thist allows us to trace the redistribution of resonance positions and resonance widths with the growth of v(C) from the weak-coupling to the strong-coupling regime.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gorev M. V., Bondarev V. S., Flerov I. N., Sciau P., Savariault J. M.
Заглавие : Heat capacity study of double perovskite-like compounds BaTi1-xZrxO3
Разночтения заглавия :авие SCOPUS: Heat capacity study of double perovskite-like compounds BaTi 1 - XZrxO3
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2005. - Vol. 47, Is. 12. - P2304-2308. - ISSN 1063-7834, DOI 10.1134/1.2142895
Примечания : Cited References: 19
Предметные рубрики: BATIO3
BA(TI1-XZRX)O-3
FERROELECTRICS
CERAMICS
STATE
FILMS
FIELD
Аннотация: The temperature dependence of the heat capacity of two compositions in the solid solution system BaTi1 - xZrxO3 (x = 0.25, 0.35) was measured using adiabatic calorimetry. In the T-x phase diagram, these compounds occupy positions near the crossover from conventional ferroelectric behavior to the relaxor state. Both compounds reveal diffuse heat capacity anomalies: two anomalies in the temperature ranges 250-350 and 150-200 K at x = 0.35 and one anomaly within the range similar to 150-320 K at x = 0.25. The results obtained are discussed together with structural and dielectric measurements. (c) 2005 Pleiades Publishing, Inc.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Parshin A. M., Barannik A. V., Zyryanov V. Ya., Shabanov V. F.
Заглавие : Interference of nonpolarized light in liquid crystal domains on a polymer surface
Место публикации : J. Opt. Soc. Am. B. - 2019. - Vol. 36, Is. 7. - P.1845-1849. - ISSN 0740-3224, DOI 10.1364/JOSAB.36.001845. - ISSN 1520-8540(eISSN)
Примечания : Cited References: 23
Предметные рубрики: FRIEDERICKSZ THRESHOLD
FIELD
LAYER
FILM
Аннотация: The interference of nonpolarized light transmitted through an ensemble of nematic liquid crystal domains formed on a polycarbonate surface has been investigated. A model based on the superposition of the ordinary and extraordinary beams passing through domains with a radial structure has been developed. Expressions for the phase difference and intensity of the interfering beams have been derived that take into account the distribution of the liquid crystal director field. The dependences of the optical transmittance of a domain layer on the applied voltage have been calculated with regard to the material and optical constants of a liquid crystal and structural features and averaged morphological parameters of individual domains in the experimental sample. The results of the calculation are consistent with the experimental data, which confirms the validity of the proposed model. (C) 2019 Optical Society of America
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Popkov S. I., Shaikhutdinov K. A., Petrov M. I.
Заглавие : Investigation of the Josephson coupling through a magnetoactive barrier (ferrimagnet, paramagnet) in Y3/4Lu1/4Ba2Cu3O7+Y-3(Al1-xFex)(5)O-12 composites
Разночтения заглавия :авие SCOPUS: Investigation of the Josephson coupling through a magnetoactive barrier (ferrimagnet, paramagnet) in Y3/4Lu1/4Ba 2Cu3O7 + Y3(Al1 - X Fe x )5O12 composites
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2006. - Vol. 48, Is. 11. - P2046-2055. - ISSN 1063-7834, DOI 10.1134/S1063783406110023
Примечания : Cited References: 41
Предметные рубрики: S-F-S
MAGNETIC-PROPERTIES
RESISTIVE PROPERTIES
JUNCTION NETWORK
SUPERCONDUCTOR
Y3FE5-XALXO12
TRANSITION
TRANSPORT
METAL
FIELD
Аннотация: The transport properties of two-phase composites consisting of a high-temperature superconductor and a nonsuperconducting component with magnetic ordering are analyzed. These composites are considered as a network of "superconductor-magnetoactive insulator-superconductor" weak links of the Josephson type. Substituted garnets Y-3(Al1 - x Fe (x) )(5)O-12 (x = 0, ..., 1.0) are used as a magnetoactive component. The composites under investigation contain 92.5 vol % Y3/4Lu1/4Ba2Cu3O7 (the high-temperature superconductor) and 7.5 vol % Y-3(Al1 - x Fe (x) )(5)O-12 (x = 0, ..., 1.0). It is shown that an increase in the iron content in the Y-3(Al1 - x Fe (x) )(5)O-12 garnet leads to a reduction of the Josephson coupling strength: the temperature range in which the electrical resistance of the composites is equal to zero is reduced, and the critical current density at a temperature of 4.2 K decreases exponentially. For composites in which the iron content in the Y-3(Al1 - x Fe (x) )(5)O-12 garnet is higher than 0.1, the temperature dependence of the electrical resistance R(T) at temperatures below the transition point T-C of high-temperature superconductor crystallites has a portion in the range T-m -T-C where the resistance R(T) is independent of the transport current and the magnetic field strength. Below the temperature T-m , the dependences of the electrical resistance R(T) of the composites are nonlinear functions of the current and involve a considerable contribution from magnetoresistance. This behavior is characteristic of a network of Josephson junctions. The temperature T-m decreases with an increase in the iron content in the Y-3(Al1 - x Fe (x) )(5)O-12 garnet. The appearance of the above feature in the temperature dependences of the electrical resistance R(T) is interpreted as complete suppression of the Josephson coupling in the temperature range above T (m) due to the interaction of supercurrent carrier pairs with magnetic moments of iron atoms in the dielectric barriers separating high-temperature superconductor grains.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Korshunov M. M., Eremin I., Shorikov A., Anisimov V. I., Renner M., Brenig W.
Заглавие : Itinerant in-plane magnetic fluctuations and many-body correlations in NaxCoO2
Разночтения заглавия :авие SCOPUS: Itinerant in-plane magnetic fluctuations and many-body correlations in Nax Co O2
Место публикации : Phys. Rev. B: AMERICAN PHYSICAL SOC, 2007. - Vol. 75, Is. 9. - Ст.94511. - ISSN 1098-0121, DOI 10.1103/PhysRevB.75.094511
Примечания : Cited References: 47
Предметные рубрики: TRANSITION-METALS
WAVE-FUNCTIONS
HUBBARD-MODEL
FERMI-SURFACE
ENERGY-BANDS
FERROMAGNETISM
APPROXIMATION
DIMENSIONS
SYSTEMS
FIELD
Аннотация: Based on the ab initio band structure for NaxCoO2, we derive the single-electron energies and the effective tight-binding description for the t(2g) bands using projection procedure. Due to the presence of the next-nearest-neighbor hoppings, a local minimum in the electronic dispersion close to the Gamma point of the first Brillouin zone forms. Correspondingly, in addition to a large Fermi surface, an electron pocket close to the Gamma point emerges at high doping concentrations. The latter yields a scattering channel, resulting in a peak structure of the itinerant magnetic susceptibility at small momenta. This indicates dominant itinerant in-plane ferromagnetic fluctuations above a certain critical concentration x(m), in agreement with neutron scattering data. Below x(m), the magnetic susceptibility shows a tendency toward the antiferromagnetic fluctuations. We further analyze the many-body effects on the electronic and magnetic excitations using various approximations applicable for different U/t ratios.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Tsipotan A. S., Gerasimova M. A., Slabko V. V., Aleksandrovsky A. S.
Заглавие : Laser-induced wavelength-controlled self-assembly of colloidal quasi-resonant quantum dots
Коллективы : Grant of Ministry of Education and Science of the Russian Federation [3.1749.2014/K, 214/71]; RFBR [14-02-00219 A]
Место публикации : Opt. Express: Optical Society of America, 2016. - Vol. 24, Is. 10. - P.11145-11150. - ISSN 1094-4087, DOI 10.1364/OE.24.011145
Примечания : Cited References:18. - This research is partially supported by Grant of the Ministry of Education and Science of the Russian Federation for Siberian Federal University (projects No 3.1749.2014/K, 214/71) and RFBR, research project No. 14-02-00219 A.
Предметные рубрики: Organized aggregation
Metal nanoparticles
Optical binding
Dynamics
Field
Аннотация: Self-assembly of colloidal semiconductor quantum dots controlled solely by laser-induced interaction is demonstrated for the first time. Pairs of CdTe nanoparticles are formed under irradiation with nanosecond pulses at wavelengths 555 or 560 nm. Formation of pairs is justified by corresponding changes of absorption spectra. Conditions of the experiment are in excellent agreement with those predicted by the theory of laser-induced dipole-dipole interaction of QDs. The fraction of QDs assembled into pairs is up to 47%. (C) 2016 Optical Society of America
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Loiko V. A., Zyryanov V. Ya., Konkolovich A. V., Miskevich A. A.
Заглавие : Light transmission of polymer-dispersed liquid crystal layer composed of droplets with inhomogeneous surface anchoring
Место публикации : Opt. Spectrosc.: MAIK Nauka-Interperiodica / Springer, 2016. - Vol. 120, Is. 1. - P.143-152. - ISSN 0030-400X, DOI 10.1134/S0030400X16010112. - ISSN 1562-6911(eISSN)
Примечания : Cited References:43. - This work was supported by the National Academy of Sciences of Belarus and the Siberian Branch of the Russian Academy of Sciences (project no. 36) and the Belarusian Republican Foundation for Fundamental Research (project no. F15SO-039).
Предметные рубрики: NEMATIC DROPLETS
IONIC MODIFICATION
FIELD
TRANSITIONS
SCATTERING
PARTICLES
INTERFACE
DISPLAYS
Аннотация: We have developed a model and realized an algorithm for the calculation of the coefficient of coherent (direct) transmission of light through a layer of liquid crystal (LC) droplets in a polymer matrix. The model is based on the Hulst anomalous diffraction approximation for describing the scattering by an individual particle and the Foldy-Twersky approximation for a coherent field. It allows one to investigate polymer dispersed LC (PDLC) materials with homogeneous and inhomogeneous interphase surface anchoring on the droplet surface. In order to calculate the configuration of the field of the local director in the droplet, the relaxation method of solving the problem of minimization of the free energy volume density has been used. We have verified the model by comparison with experiment under the inverse regime of the ionic modification of the LC-polymer interphase boundary. The model makes it possible to solve problems of optimization of the optical response of PDLC films in relation to their thickness and optical characteristics of the polymer matrix, sizes, polydispersity, concentration, and anisometry parameters of droplets. Based on this model, we have proposed a technique for estimating the size of LC droplets from the data on the dependence of the transmission coefficient on the applied voltage.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Popov M. A., Petrakovskii G. A., Zinenko V. I.
Заглавие : Magnetic properties of copper metaborate: Two-parameter phenomenological model
Разночтения заглавия :авие SCOPUS: Magnetic Properties of Copper Metaborate: Two-Parameter Phenomenological Model
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2004. - Vol. 46, Is. 3. - P491-497. - ISSN 1063-7834, DOI 10.1134/1.1687867
Примечания : Cited References: 9
Предметные рубрики: SOLITON LATTICE
CUB2O4
FIELD
Аннотация: Symmetry analysis is performed for the magnetic subsystem of copper metaborate, and a phenomenological model is proposed with two two-component order parameters that correspond to ferromagnetism and antiferromagnetism vectors lying in the tetragonal plane of this crystal. Owing to the I (4) over bar 2d space group of symmetry of this crystal, the thermodynamic potential contains the Lifshitz invariant having the form of an antisymmetric product of the order parameters and their spatial derivatives. Analysis of this model shows that the temperatures of ordering in the magnetic subsystem and of the formation of a spiral structure in it can be different. This fact allows numerical calculation of the temperature dependences of the spiral wave vector, magnetization, and intensities of first- and third-order magnetic satellites in the incommensurate phase that arise in neutron elastic scattering, as well as the field dependence of the magnetization. The experimental data, including a magnetic-field-temperature phase diagram, are satisfactorily described. The parameters of the phenomenological thermodynamic potential of the magnetic subsystem of copper metaborate are estimated. (C) 2004 MAIK "Nauka / Interperiodica".
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