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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Вальков, Валерий Владимирович, Дзебисашвили, Дмитрий Михайлович
Заглавие : Особенности спектра тяжелых фермионов в скошенной фазе антиферромагнитных интерметаллидов
Место публикации : Теоретическая и математическая физика. - Москва: Математический институт им. В.А. Стеклова РАН, 2010. - Т. 162, № 1. - С. 125-149. - ISSN 0564-6162, DOI 10.4213/tmf6460. - ISSN 2305-3135(eissn)
Предметные рубрики:
Ключевые слова (''Своб.индексиров.''): периодическая модель андерсона--тяжелые фермионы--антиферромагнетизм--скошенная фаза
Аннотация: Изучено влияние индуцированного магнитным полем скоса магнитных подрешеток на энергетическую структуру тяжелофермионных квазичастиц в интерметаллидах с антиферромагнитным типом упорядочения. Исследования выполнены в рамках эффективного гамильтониана периодической модели Андерсона в режиме сильных электронных корреляций. В результате учета виртуальных забросов в высокоэнергетические двоечные состояния этот гамильтониан включает обменные взаимодействия между спиновыми моментами f-ионов, а также s–f-обменную связь между двумя подсистемами. Для неколлинеарной геометрии задачи введено унитарное преобразование, позволившее свести уравнение восьмой степени для спектра тяжелых фермионов к двум уравнениям четвертой степени. Показано, что характер квазиимпульсной зависимости энергии тяжелых фермионов претерпевает качественные изменения при переходе от антиферромагнитной фазы к фазе со значительным углом скоса, возникающим при наложении внешнего магнитного поля.
РИНЦ
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Изотов, Андрей Викторович, Беляев, Борис Афанасьевич, Соловьев, Платон Николаевич, Волошин, Александр Сергеевич
Заглавие : Микромагнитное моделирование и численный анализ процессов перемагничивания двухслойных тонкопленочных структур ферромагнетик/антиферромагнетик
Место публикации : Изв. вузов. Физика. - 2013. - Т. 56, № 8/2. - С. 230-232
Примечания : Работа выполнена при финансовой поддержке ФЦП «Научные и научно-педагогические кадры инновационной России 2009−2013»
Ключевые слова (''Своб.индексиров.''): микромагнитное моделирование--ферромагнетик/антиферромагнетик--петля гистерезиса--обменное смещение--коэрцитивная сила--micromagnetic simulation--coercivity--ferromagnetic/antiferromagnetic--hysteresis loop--exchange bias
Аннотация: На основе численного микромагнитного моделирования проведено исследование процессов перемагничивания двухслойных тонкопленочных структур ферромагнетик/антиферромагнетик. Сделан анализ влияния параметров структуры на величину поля обменного сдвига и коэрцитивной силы. Результаты расчета сравниваются с экспериментальными и теоретическими данными.On the basis of the numerical micromagnetic simulation the study of magnetization reversal processes in thin-film ferromagnetic/antiferromagnetic bilayers was performed. The analysis of influence of parameters of the structure on exchange bias field and coercive force was carried out. Calculation results are compared with experimental and theoretical data.
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Fedoseeva N. V., Aplesnin S. S., Nikolaev E. M., Perepelitsa A. P.
Заглавие : Weak ferromagnetism and magnetic-behavior of (CH3NH3)2MNCL4 quasidimetric antiferromagnetic
Место публикации : Fiz. Tverd. Tela: MEZHDUNARODNAYA KNIGA, 1994. - Vol. 36, Is. 9. - P.2609-2617. - ISSN 0367-3294
Примечания : Cited References: 8
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kliava J., Malakhovskii A. V., Edelman I. S., Potseluyko A. M., Petrakovskaja E. A., Bruckental I., Yeshurun Y., Zarubina T.
Заглавие : Unusual magnetic phase transitions in Gd3+ clusters in multicomponent oxide glasses
Разночтения заглавия :авие SCOPUS: Unusual magnetic phase transitions in Gd 3+ clusters in multicomponent oxide glasses
Место публикации : J. Supercond. Nov. Magn.: SPRINGER, 2007. - Vol. 20, Is. 2. - P149-153. - ISSN 1557-1939, DOI 10.1007/s10948-006-0116-4
Примечания : Cited References: 7
Предметные рубрики: GADOLINIUM
RESONANCE
Ключевые слова (''Своб.индексиров.''): oxide glasses--gadolinium--magnetic clusters--superparamagnetism--gadolinium--magnetic clusters--oxide glasses--superparamagnetism--magnetic clusters--magnetic phase transitions--oxide glasses--weiss constant--antiferromagnetic materials--ferromagnetic materials--gadolinium--magnetic anisotropy--magnetic susceptibility--paramagnetic resonance--phase transitions--positive ions--superparamagnetism--glass
Аннотация: Magnetic susceptibility, EPR and optical properties have been studied in a glass system {20La(2)O(3) - 22Al(2)O(3) - 23B(2)O(3) - 35(SiO2 + GeO2)} with a part of La2O3 substituted by Gd2O3 in different concentrations. Positive Weiss constants have been found in more heavily doped glasses; two magnetic transitions at 55 and 12 K have been detected and ascribed, respectively, to ferromagnetic and antiferromagnetic clusters of Gd3+ ions. The EPR spectra confirm the clustering at higher Gd contents. At low temperatures the cluster-related resonance indicates an onset of magnetic anisotropy. The clustering, depending on the Gd concentration, correlates with a shift to lower energies of the strong optical absorption band edge.
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Men'shikov V. V., Rudenko V. V., Tugarinov V. I., Vorotynov A. M., Ovchinnikov S. G.
Заглавие : Uniaxial magnetic anisotropy of rhombohedral CoCO3 crystals at T = 0 K
Место публикации : Phys. Solid State: MAIK Nauka-Interperiodica / Springer, 2014. - Vol. 56, Is. 3. - P.468-472. - ISSN 1063-7834, DOI 10.1134/S1063783414030196. - ISSN 1090-6460
Примечания : Cited References: 21
Предметные рубрики: ANTIFERROMAGNETIC RESONANCE
IONS
Аннотация: A method for calculating the contribution of exchange interaction to uniaxial anisotropy with the use of g' factors has been worked out using CoCO3 crystals as an example. The calculated contribution of dipole-dipole interactions to the anisotropy of CoCO3 is 0.93 cm(-1). The sum of the contributions to the anisotropy constant of CoCO3 with the inclusion of the dipole-dipole interactions is 36.1 cm(-1).
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Krasikov A. A., Popkov S. I., Semenov S. V., Volochaev M. N., Velikanov D. A., Kirillov V. L., Martyanov O. N.
Заглавие : Uncompensated magnetic moment and surface and size effects in few-nanometer antiferromagnetic NiO particles
Место публикации : J. Magn. Magn. Mater. - 2021. - Vol. 539. - Ст.168343. - ISSN 03048853 (ISSN), DOI 10.1016/j.jmmm.2021.168343
Примечания : Cited References: 98. - The TEM study was carried out on the equipment of the Krasnoyarsk Territorial Center for Collective Use, Krasnoyarsk Scientific Center, Siberian Branch, Russian Academy of Sciences
Аннотация: The analysis of the M(H) magnetization curves of antiferromagnetic nanoparticles yields information about magnetic subsystems formed in these objects, which are characterized by a large fraction of surface atoms. However, in the conventionally investigated experimental magnetic field range of up to 60–90 kOe, this analysis often faces the ambiguity of distinguishing the Langevin function-simulated contribution of uncompensated magnetic moments μun of particles against the background of a linear-in-field dependence (the antiferromagnetic susceptibility and other contributions). Here, this problem has been solved using a pulsed technique, which makes it possible to significantly broaden the range of external fields in which the μun contribution approaches the saturation. Nanoparticles of a typical NiO antiferromagnet with an average size of d ~ 4.5 nm have been investigated. Based on the thorough examination of the M(H) magnetization curves measured in pulsed fields of up to 250 kOe, a model of the magnetic state of NiO nanoparticles of such a small size has been proposed. The average moment is ~130 μB (μB is the Bohr magneton) per particle, which corresponds to 60–70 decompensated spins of nickel atoms localized, according to the Néel hypothesis (μun ~ d3/2), both on the surface and in the bulk of a particle. A part of the surface spins unrelated to the antiferromagnetic core form another subsystem, which behaves as free paramagnetic atoms. Along with the antiferromagnetic core, an additional linear-in-field contribution has been detected, which is apparently related to superantiferromagnetism, i.e., the size effect inherent to small antiferromagnetic particles.
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S.
Заглавие : Two-particle spin-singlet excitations in coupled spin-1/2 antiferromagnetic alternating chains
Место публикации : J. Phys.: Condens. Matter: IOP PUBLISHING LTD, 2001. - Vol. 13, Is. 14. - P.3403-3410. - ISSN 0953-8984, DOI 10.1088/0953-8984/13/14/313
Примечания : Cited References: 14
Предметные рубрики: MAGNETIC-PROPERTIES
LIGHT-SCATTERING
CUGEO3
S=1/2
Ключевые слова (''Своб.индексиров.''): antiferromagnetic materials--approximation theory--chemical bonds--electron transport properties--monte carlo methods--particles (particulate matter)--quantum theory--thermal effects--antiferromagnetic alternating chains--excitation spectrum--interchain exchange--mean-field approximation--quantum monte carlo method--singlet gaps--spin-singlet excitations--energy gap
Аннотация: The spectrum of the two-particle spin-singlet (DeltaS(z) = 0, +/-1) excitations of a weakly coupled antiferromagnetic spin-1/2 alternating (J(1) +/- delta) chain is calculated using a mean-field approximation for the interchain exchange (J(2)) by the quantum Monte Carlo method. The bandwidth change of these excitations, the mass gaps in the singlet-singlet excitation spectrum, the top boundaries of the bands and the velocities of these excitations are estimated as functions of the alternating bond delta. The temperatures at which the singlet gaps close are determined.
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuz'min E. V.
Заглавие : Two-Dimensional Heisenberg Model with Spin s=1/2 and Antiferromagnetic Exchange Treated as a Spin Liquid
Коллективы : Russian Foundation for Basic Research [00-02-16110]
Разночтения заглавия :авие SCOPUS: Two-dimensional Heisenberg model with spin s = 1/2 and antiferromagnetic exchange treated as a spin liquid
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2002. - Vol. 44, Is. 6. - P1122-1129. - ISSN 1063-7834, DOI 10.1134/1.1485019
Примечания : Cited References: 14. - This study was supported by the Russian Foundation for Basic Research, project no. 00-02-16110.
Аннотация: The spin system of the Heisenberg model (s = 1/2) on a square lattice with antiferromagnetic (AFM) exchange between nearest neighbors (in which there is no long-range magnetic order at any T not equal 0) is treated as a spatially homogeneous isotropic spin liquid. The double-time temperature Green's function method is used in the framework of a second-step decoupling scheme. It is shown that, as T - 0, the spin liquid goes over (without any change in symmetry) to a singlet state with energy (per bond) epsilon(0) = -0.352 and the correlation length diverges as xi proportional to T(-1) exp(T(0)/T). The spatial spin correlators oscillate in sign with distance, as in the AFM state. The theory allows one to calculate the main characteristics of the system in all temperature ranges. (C) 2002 MAIK "Nauka/Interperiodica".
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bykov A. A., Zobkalo I. A., Dubrovskii A. A., Smirnov O. P., Nikitin S. E., Terent'ev K. Yu., Gavrilov S. V., Shaikhutdinov K. A.
Заглавие : Two-dimensional antiferromagnetic correlations in an La1.4Sr1.6(Mn0.9Co0.1)2O7 single crystal
Место публикации : J. Exp. Theor. Phys.: Maik Nauka-Interperiodica Publishing, 2017. - Vol. 124, Is. 5. - P.786-791. - ISSN 10637761 (ISSN), DOI 10.1134/S1063776117050120
Примечания : Cited References: 20
Ключевые слова (''Своб.индексиров.''): antiferromagnetism--cobalt--cobalt compounds--lanthanum compounds--magnetization--magnetostriction--antiferromagnetic correlations--bi-layer--ferromagnetic orderings--field dependence--lanthanum manganites--single-crystal neutron diffraction--single crystals
Аннотация: The temperature and field dependences of the magnetization, the electrical resistivity, and the magnetostriction of bilayer lanthanum manganite La1.4Sr1.6Mn2O7 single crystals and cobalt-doped La1.4Sr1.6(Mn0.9Cu0.1)2O7 are measured. The magnetostriction of the cobalt-doped compound increases as compared to the initial La1.4Sr1.6Mn2O7 compound, and the magnetization and the magnetoresistance of the former compound change substantially. Powder and single-crystal neutron diffraction patterns are used to detect ferromagnetic ordering in La1.4Sr1.6(Mn0.9Co0.1)2O7 at a temperature below TC ~ 45(2) K, and this ordering coexists with antiferromagnetic correlations, which develop at temperatures below TC ~ 80(5) K. © 2017, Pleiades Publishing, Inc.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Pankrats A. I., Demidov A. A., Ritter C., Velikanov D. A., Semenov S. V., Tugarinov V. I., Temerov V. L., Gudim, I. A.
Заглавие : Transformation from an easy-plane to an easy-axis antiferromagnetic structure in the mixed rare-earth ferroborates PrxY1-xFe3(BO3)4: Magnetic properties and crystal field calculations
Место публикации : J. Phys.: Condens. Matter: IOP Publishing, 2016. - Vol. 28, Is. 39. - Ст.396001. - ISSN 09538984 (ISSN), DOI 10.1088/0953-8984/28/39/396001
Примечания : Cited References: 27. - This work was supported by the Russian Foundation for Basic Research (project no. 15-42-04186_r_sibir'_a).
Ключевые слова (''Своб.индексиров.''): magnetic phase transitions--rare-earth ferroborates rfe3(bo3)4--antiferromagnetic resonance
Аннотация: The magnetic structure of the mixed rare-earth system PrxY1-xFe3(BO3)4 (x = 0.75, 0.67, 0.55, 0.45, 0.25) was studied via magnetic and resonance measurements. These data evidence the successive spin reorientation from the easy-axis antiferromagnetic structure formed in PrFe3(BO3)4 to the easy-plane one of YFe3(BO3)4 associated with the weakening of the magnetic anisotropy of the Pr subsystem due to its diamagnetic dilution by nonmagnetic Y. This reorientation occurs through the formation of an inclined magnetic structure, as was confirmed by our previous neutron research in the range of x = 0.67 ? 0.45. In the compounds with x = 0.75 and 0.67 whose magnetic structure is close to the easy-axis one, a two-step spin reorientation takes place in the magnetic field H||c. Such a peculiarity is explained by the formation of an interjacent inclined magnetic structure with magnetic moments of Fe ions located closer to the basal plane than in the initial state, with these intermediate states remaining stable in some ranges of the magnetic field. An approach based on a crystal field model for the Pr3+ ion and the molecular-field approximation is used to describe the magnetic characteristics of the system PrxY1-xFe3(BO3)4. With the parameters of the d-d and f-d exchange interactions, of the magnetic anisotropy of the iron subsystem and of the crystal field parameters of praseodymium thus determined, it is possible to achieve a good agreement between the experimental and calculated temperature and field dependences of the magnetization curves (up to 90 kOe) and magnetic susceptibilities (2-300 K). © 2016 IOP Publishing Ltd.
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11.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Abramova G. M., Gerasimova J. V., Kolesov B., Zhandun V. S., Molokeev M. S., Zharkov S. M., Vtyurin A. N.
Заглавие : The magnon mode in Raman spectra of the antiferromagnetic α-MnS
Коллективы : Российская академия наук, Физико-технический институт им. А.Ф. Иоффе РАН, "Spin Waves", International Symposium
Место публикации : International Symposium "Spin Waves 2018": Program. - 2018. - Sec. 3: Magnonics and propagation of spin waves. - 3-1
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Mitskan V. A., Petrakovskii G. A.
Заглавие : The magnetoelastic mechanism of singlet phase formation in a two-dimensional quantum antiferromagnet
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2006. - Vol. 102, Is. 2. - P234-247. - ISSN 1063-7761, DOI 10.1134/S106377610602004X
Примечания : Cited References: 18
Предметные рубрики: GROUND-STATE
SPIN
TRANSITION
CUGEO3
MODEL
Ключевые слова (''Своб.индексиров.''): crystal lattices--elasticity--mathematical models--oscillations--phase diagrams--phase transitions--quantum theory--two dimensional--atomic representation--magnetoelastic mechanism--quantum antiferromagnets--singlet phase formation--antiferromagnetic materials
Аннотация: A model describing the second-order phase transition with respect to the magnetoelastic coupling parameter from the anti ferromagnetic (AFM) to the singlet state in a two-dimensional quantum magnet on a square lattice is proposed. The spectrum of elementary excitations in the singlet and AFM phases is calculated using an atomic representation, and the evolution of transverse and longitudinal branches of this spectrum is studied in the vicinity of the transition point. It is established that the AFM to singlet phase transition is related to softening of the longitudinal branch of oscillations. In the singlet phase, the gap plays the role of a parameter characterizing the distance to the phase transition point. It is shown that the spectrum of transverse oscillations in the AFM phase corresponds to the Goldstone boson. Based on an analysis of the stability of the spectrum of elementary excitations, a phase diagram is constructed that determines the regions of the existence of phases with plaquette-deformed lattices.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : OVCHINNIKOV S.G.
Заглавие : THE INFLUENCE OF THE ANTIFERROMAGNETISM ON THE ELECTRONIC-STRUCTURE OF LA2CUO4
Разночтения заглавия :авие SCOPUS: The influence of the antiferromagnetism on the electronic structure of La2CuO4
Место публикации : J. Supercond.: PLENUM PUBL CORP, 1995. - Vol. 8: University-of-Miami Workshop on High-Temperature Superconductivity - Physical Properties and Mechanisms (JAN 05-11, 1995, CORAL GABLES, FL), Is. 5. - P675-676. - ISSN 0896-1107, DOI 10.1007/BF00727473
Примечания : Cited References: 15
Предметные рубрики: OXIDES
MODEL
Ключевые слова (''Своб.индексиров.''): electron correlations--electron structure--spin fluctuations--electron correlations--electron structure--spin fluctuations--antiferromagnetism--band structure--calculations--correlation theory--electrons--lanthanum compounds--paramagnetism--perturbation techniques--antiferromagnetic phase--electron correlations--intercluster interactions--spin fluctuations--electronic structure
Аннотация: The quasiparticle approach for electronic structure calculations considering strong electron correlations is given. The exact diagonalization of a multiband Hubbard Hamiltonian for a small cluster is combined with perturbation theory for intercluster hopping. The band structure of paramagnetic and antiferromagnetic La2CuO4 are discussed.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Martynov S. N.
Заглавие : The incommensurate magnetic structure of a tetragonal antiferromagnet with antisymmetric exchange
Место публикации : J. Exp. Theor. Phys. - 2009. - Vol. 109, Is. 6. - P.979-988. - ISSN 1063-7761, DOI 10.1134/S1063776109120097
Примечания : Cited References: 34
Предметные рубрики: FLUCTUATION-INDUCED PHASE
FIELD-INDUCED GAP
COPPER METABORATE
WEAK FERROMAGNETISM
SOLITON LATTICE
SPIN-WAVES
CUB2O4
BA2CUGE2O7
CSCUCL3
CHAINS
Ключевые слова (''Своб.индексиров.''): anti-symmetric--antiferromagnetic sublattices--antiferromagnets--antisymmetric exchange--exchange bonds--ferromagnetic component--ferromagnetic moments--ginzburg-landau functional--incommensurate magnetic structures--mean field approximation--modulation vectors--polarization planes--polarization vectors--symmetry groups--antiferromagnetic materials--antiferromagnetism--crystal orientation--crystal symmetry--ferromagnetic materials--ferromagnetism--magnetic devices--magnetic structure--modulation--polarization--vector spaces--vectors--crystallography
Аннотация: Analysis of the incommensurate magnetic structure that emerges for two coexisting types of the antisymmetric Dzyaloshinski-Moriya exchange interaction (the weakly ferromagnetic component of vector D along the tetragonal axis and the helicoidal component distributed in the tetragonal plane) is carried out for the first time for a tetragonal antiferromagnet. The helicoidal component for each pair of interacting spins has a 2D distribution; its direction in the tetragonal plane depends on the direction of the exchange bond in each pair. The Lifshits invariant of the Ginzburg-Landau functional is obtained, which is responsible for the formation of an incommensurate magnetic structure for such a distribution. It is shown in the mean field approximation that the incommensurate magnetic structure that forms in this case is a nonlinear double helicoid with a modulation vector lying in the tetragonal plane and with a varying angle between the polarization planes of quasi-antiferromagnetic sublattices. The ground state of the magnet is degenerate in the orientation of the modulation vector in the tetragonal plane. The rate of variation in the orientations of moments in the polarization planes passing through the tetragonal axis is controlled by the angle between the directions of the moments and the tetragonal axis. The local weakly ferromagnetic moment remaining in the polarization plane varies in magnitude and sign. The relation between the orientations of the modulation and polarization vectors is derived for the cases of simple and inversion tetragonal axes in the space symmetry group of the crystal.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Dzebisashvili D. M.
Заглавие : The electron energy spectrum and superconducting transition temperature of strongly correlated fermions with three-center interactions
Место публикации : J. Exp. Theor. Phys.: AMER INST PHYSICS, 2005. - Vol. 100, Is. 3. - P608-616. - ISSN 1063-7761, DOI 10.1134/1.1901772
Примечания : Cited References: 29
Предметные рубрики: T-J MODEL
BAND HUBBARD-MODEL
VALENCE BOND STATE
RANGE-ORDER
SYSTEMS
WAVE
Ключевые слова (''Своб.индексиров.''): antiferromagnetic materials--approximation theory--fermions--ground state--hamiltonians--superconductivity--density of states--electron energy spectrum--strongly correlated fermions--superconducting phase--superconducting transition temperature
Аннотация: The renormalizations of the fermionic spectrum are considered within the framework of the t-J* model taking into account three-center interactions (H-(3)) and magnetic fluctuations. Self-consistent spin dynamics equations for strongly correlated fermions with three-center interactions were obtained to calculate quasi-spin correlators. A numerical self-consistent solution to a system of ten equations was obtained to show that, in the nearest-neighbor approximation, simultaneously including H-(3) and magnetic fluctuations at n n(1) (n(1) approximate to 0.72 for 2t/U = 0.25) caused qualitative changes in the structure of the energy spectrum. A new Van Hove singularity is then induced in the density of states, and an additional maximum appears in the T-c(n) concentration dependence of the temperature of the transition to the superconducting phase with order parameter symmetry of the d(x2-y2) type. (C) 2005 Pleiades Publishing, Inc.
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16.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Sofronova S. N., Kolesnikova E. M., Eremin E. V., Volkov N. V., Bezmaternykh L. N., Molokeev M. S.
Заглавие : Temperature-field evolution of antiferromagnetic phase of ludwigite Ni[[d]]3-x[[/d]]Mn[[d]]x[[/d]]BO[[d]]5[[/d]]
Коллективы : Euro-Asian Symposium "Trends in MAGnetism": Nanomagnetism
Место публикации : V Euro-Asian simposium "Trend in MAGnetism": Nanomagnetism: abstracts. - Vladivostok: FEFU, 2013. - С. 242. - ISBN 978-5-7444-3124-2
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Korshunov M. M., Zakharova E. V.
Заглавие : Temperature evolution of spin-polaron in-gap states in undoped antiferromagnetic cuprates
Коллективы :
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2008. - Vol. 50, Is. 8. - P1401-1406. - ISSN 1063-7834, DOI 10.1134/S1063783408080027
Примечания : Cited References: 26. - This work was supported by the Russian Foundation for Basic Research (project nos. 06-02-16100 and 0602- 90537-BNTS), the Presidium of the Russian Academy of Sciences (program "Quantum Macrophysics"), and INTAS (YS grant no. 05-109-4891).
Предметные рубрики: J MODEL
LA2-XSRXCUO4
SUPERCONDUCTORS
BAND
Аннотация: The temperature evolution of in-gap states created by the spin polaron effect and located within the gap with charge transfer between the valence and conduction bands is studied for the case of strong electron correlations using the t-t'-t ''-J model of antiferromagnetic undoped cuprates. The effect of temperature is taken into account by temperature renormalization of the magnon concentration, which is calculated using the Heisenberg model with inclusion of weak interlayer exchange and weak in-plane spin anisotropy, and by introducing a Lorentzian with a temperature-dependent half-width in the form corresponding to the marginal Fermi liquid model. With increasing temperature, the spectral weight of the in-gap state, which is proportional to the magnon concentration, grows leading to an increased intensity of the corresponding peak of the spectral function in all points of the Brillouin zone. At points (pi/2, pi/2) and (pi, 0), the main peak is approached by the satellite peak related to the in-gap band and, at points (0, 0) and (pi, pi), the peaks move away from each other.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Rudenko V. V., Tugarinov V. I.
Заглавие : Temperature dependence of the uniaxial magnetic anisotropy of rhombohedral antiferromagnetic crystals with ions in the S state
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2010. - Vol. 52, Is. 1. - P112-116. - ISSN 1063-7834, DOI 10.1134/S1063783410010191
Примечания : Cited References: 19
Предметные рубрики: ALPHA-FE2O3
RESONANCE
FIELD
MNF2
Аннотация: The contributions of the anisotropic exchange to the firstand second-order uniaxial anisotropy constants have been calculated for hematite at T = 0 K and arbitrary temperatures. The results of the calculations and the most significant mechanisms are taken into account in interpreting the temperature dependence of the anisotropy in rhombohedral antiferromagnetic crystals. The first-order anisotropy constant for hematite is described by the dipole interaction, contributions of the "single-ion" nature, and relatively small contributions of the anisotropic exchange. The second-order constant for hematite includes the "single-ion" contribution and the contribution of the anisotropic exchange. For FeBO(3) and MnCO(3) crystals, the main contributions to the first-order anisotropy constant come from the dipole and single-ion mechanisms.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Popkov S. I., Krasikov A. A., Balaev A. D., Dubrovskiy A. A., Stolyar S. V., Yaroslavtsev R. N., Ladygina V. P., Iskhakov R. S.
Заглавие : Temperature behavior of the antiferromagnetic susceptibility of nanoferrihydrite from the measurements of the magnetization curves in fields of up to 250 kOe
Коллективы : Russian Foundation for Basic Research; Government of Krasnoyarsk region; Krasnoyarsk Regional Foundation of Supporting the Scientific and Scientific-Engineering Activity in the framework of the scientific projects [17-42-240138, 17-43-240527]
Место публикации : Phys. Solid State: MAIK Nauka-Interperiodica / Springer, 2017. - Vol. 59, Is. 10. - P.1940-1946. - ISSN 1063-7834, DOI 10.1134/S1063783417100031. - ISSN 1090-6460(eISSN)
Примечания : Cited References:45. - This work was supported by the Russian Foundation for Basic Research, the Government of Krasnoyarsk region, the Krasnoyarsk Regional Foundation of Supporting the Scientific and Scientific-Engineering Activity in the framework of the scientific projects nos. 17-42-240138 and 17-43-240527.
Предметные рубрики: FERRIHYDRITE NANOPARTICLES
BACTERIAL FERRIHYDRITE
HYSTERESIS
Аннотация: The cross-breeding problem of the temperature dependence of the antiferromagnetic susceptibility of ferrihydrite nanoparticles is considered. Iron ions Fe3+ in ferrihydrite are ordered antiferromagnetically; however, the existence of defects on the surface and in the bulk of nanoparticles induces a noncompensated magnetic moment that leads to a typical superparamagnetic behavior of ensemble of the nanoparticles with a characteristic blocking temperature. In an unblocked state, magnetization curves of such objects are described as a superposition of the Langevin function and the linear-in-field contribution of the antiferromagnetic “core” of the nanoparticles. According to many studies of the magnetization curves performed on ferrihydrite (and related ferritin) nanoparticles in fields to 60 kOe, dependence χAF(T) decreases as temperature increases, which was related before to the superantiferromagnetism effect. As the magnetic field range increases to 250 kOe, the values of χAF obtained from an analysis of the magnetization curves become lower in magnitude; however, the character of the temperature evolution of χAF is changed: now, dependence χAF(T) is an increasing function. The latter is typical for a system of AF particles with random orientation of the crystallographic axes. To correctly determine the antiferromagnetic susceptibility of AF nanoparticles (at least, ferrihydrite) and to search for effects related to the superantiferromagnetism effect, it is necessary to use in experiments the range of magnetic field significantly higher than that the standard value 60 kOe used in most experiments. The study of the temperature evolution of the magnetization curves shows that the observed crossover is due to the existence of small magnetic moments in the samples.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kurilova A. V., Sokolov A. Е., Sukhachev A. L., Ivanova O. S., Bogdanov K. V., Baranov M. A., Dubavik A. Y.
Заглавие : Synthesizing antiferromagnetic α-Fe2O3–rGO discs: Their magnetic and magneto-optical properties
Место публикации : Bull. Russ. Acad. Sci. Phys. - 2022. - Vol. 86, Is. 5. - P.610-613. - ISSN 10628738 (ISSN), DOI 10.3103/S106287382205015X
Примечания : Cited References: 26
Аннотация: A comprehensive study is performed of the properties of hybrid structures of iron oxide and reduced graphene oxide α-Fe2O3/rGO synthesized via “wet mixing.” It is shown that hematite nanoparticles with a comparatively uniform distribution can be encapsulated in graphene layers, and the way of preparing precursors is of critical importance in shaping the magneto-optical properties of α-Fe2O3/rGO hybrid structures.
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