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1.

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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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Dudnikov V. A., Velikanov D. A., Kazak N. V., Michel C. R., Bartolome J., Arauzo A., Ovchinnikov S. G., Patrin G. S.
Заглавие : Antiferromagnetic ordering in REM cobaltite GdCoO3
Место публикации : Phys. Solid State: MAIK Nauka-Interperiodica / Springer, 2012. - Vol. 54, Is. 1. - P.79-83. - ISSN 1063-7834, DOI 10.1134/S106378341201009X
Примечания : Cited References: 16. - This study was supported by the program of the Branch of Physical Sciences of the Russian Academy of Sciences "Strong Electron Correlations," the Russian Foundation for Basic Research (project no. 09-02-00171-a), and Federal Agency for Science and Innovations (grant no. MK-5632.2010.2).
Предметные рубрики: SPIN-STATE
RCo3O3 R
Sm
Eu
Nd
Аннотация: Temperature and magnetic-field dependences of the static magnetization of polycrystalline cobaltite GdCoO3 have been measured. The magnetic properties of the GdCoO3 sample have been studied in the paramagnetic and antiferromagnetic states. The magnetic phase diagram has been constructed. The exchange field between the Gd-Gd sublattices and the anisotropy field have been estimated.
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuz'menko A. M., Mukhin A. A., Ivanov V. Y., Kadomtseva A. M., Lebedev S. P., Bezmaternykh L. N.
Заглавие : Antiferromagnetic Resonance and Dielectric Properties of Rare-earth Ferroborates in the Submillimeter Frequency Range
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2011. - Vol. 113, Is. 1. - P113-120. - ISSN 1063-7761, DOI 10.1134/S106377611105013X
Примечания : Cited References: 27. - This work was supported by the Russian Foundation for Basic Research, project no. 10-02-00846.
Предметные рубрики: GDFE3(BO3)(4)
SPECTROSCOPY
CRYSTAL
Ключевые слова (''Своб.индексиров.''): antiferromagnetic resonance--basic parameters--effective anisotropy constant--ferroborates--ferroics--ferromagnetic orderings--frequency ranges--magnetic interactions--magnetoresonance--millimeter frequency range--rare earth ions--submillimeters--antiferromagnetic materials--crystallography--erbium--europium--ferromagnetic resonance--ion exchange--magnetic anisotropy--magnetic devices--magnetic structure--permittivity--resonance--antiferromagnetism
Аннотация: The magnetoresonance and dielectric properties of a number of crystals of a new family of multiferroics, namely, rare-earth ferroborates RFe(3)(BO(3))(4) (R = Y, Eu, Pr, Tb, Tb(0.25)Er(0.75)), are studied in the submillimeter frequency range (nu = 3-20 cm(-1)). Ferroborates with R = Y, Tb, and Eu exhibit permittivity jumps at temperatures of 375, 198, and 58 K, respectively, which are caused by the R32 - P3(1)2(1) phase transition. Antiferromagnetic resonance (AFMR) modes in the subsystem of Fe(3+) ions are detected in the range of antiferromagnetic ordering (T T(N)
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuz'menko A. M., Mukhin A. A., Ivanov V. Yu., Kadomtseva A. M., Lebedev S. P., Bezmaternykh L. N.
Заглавие : Antiferromagnetic Resonance and Dielectric Properties of Rare-earth Ferroborates in the Submillimeter Frequency Range
Место публикации : J. Exp. Theor. Phys. - MOSCOW: PLEIADES PUBLISHING INC, 2011. - Vol. 113, Is. 1. - С. 113-120. - JUL. - ISSN 1063-7761, DOI 10.1134/S106377611105013X. - ISSN 1090-6509
Примечания : Cited Reference Count: 27. - Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR) [10-02-00846], This work was supported by the Russian Foundation for Basic Research, project no. 10-02-00846.
Предметные рубрики: Physics, Multidisciplinary
Аннотация: The magnetoresonance and dielectric properties of a number of crystals of a new family of multiferroics, namely, rare-earth ferroborates RFe3(BO3)(4) (R = Y, Eu, Pr, Tb, Tb0.25Er0.75), are studied in the submillimeter frequency range (nu = 3-20 cm(-1)). Ferroborates with R = Y, Tb, and Eu exhibit permittivity jumps at temperatures of 375, 198, and 58 K, respectively, which are caused by the R32 - P3(1)2(1) phase transition. Antiferromagnetic resonance (AFMR) modes in the subsystem of Fe3+ ions are detected in the range of antiferromagnetic ordering (T≺T-N=30-40K) in all ferroborates that have either an easy-plane (Y, Eu) or easy-axis (Pr, Tb, Tb0.25Er0.75) magnetic structure. The AFMR frequencies are found to depend strongly on the magnetic anisotropy of a rare-earth ion and its exchange interaction with the Fe subsystem, which determine the type of magnetic structure and the sign and magnitude of an effective anisotropy constant. The basic parameters of the magnetic interactions in these ferroborates are found, and the magnetoelectric contribution to AFMR is analyzed.
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Pankrats A. I., Zharkov S. M., Zeer G. M., Gudim I. A.
Заглавие : Antiferromagnetic resonance and magnetic anisotropy in PrxY1−xFe3(BO3)4 crystals in the region of the magnetic structure transformation “easy axis – easy plane”
Место публикации : J. Alloys Compd. - 2022. - Vol. 909. - Ст.164821. - ISSN 09258388 (ISSN), DOI 10.1016/j.jallcom.2022.164821
Примечания : Cited References: 37. - The authors acknowledge the assistance of R. Mironov in some resonance measurements. The SEM and EDS investigations were conducted in the SFU Joint Scientific Center supported by the State assignment (#FSRZ-2020–0011) of the Ministry of Science and Higher Education of the Russian Federation
Аннотация: The spin dynamics, magnetic structures and magnetic anisotropy of single crystals PrxY1−xFe3(BO3)4 have been studied using antiferromagnetic resonance (AFMR) in a wide range of frequencies, magnetic fields, and temperatures. The frequency-field dependences of AFMR for the crystals with x = 0.25 and 0.45 are characteristic of antiferromagnets with the easy plane (EP) anisotropy. The crystals with x = 0.75 and 1.0 exhibit frequency-field dependences that are typical for antiferromagnets with the easy axis (EA) anisotropy. In these crystals, a significant decrease in the effective anisotropy fields of praseodymium upon the transition to the spin-flop state has been found. It is shown that this is the main reason for the large lability intervals, within which the regions of coexistence of the collinear and spin-flop states overlap. In the crystal with x = 0.67, the magnetic field applied along the trigonal axis of the crystal leads to the spin reorientation transition from the EA to the EP state. A magnetic phase diagram of the states on the plane "magnetic field - temperature" is built. In this crystal, the effective anisotropy field of praseodymium also decreases upon the transition to the field-induced EP state. Diamagnetic dilution of the praseodymium subsystem leads to the contribution of this subsystem to the total anisotropy field depending almost linearly on the praseodymium concentration.
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Pankrats A. I., Petrakovskii G. A., Bezmaternykh L. N., Temerov V. L.
Заглавие : Antiferromagnetic resonance and magnetic anisotropy in single crystals of the YFe3(BO3)(4)-GdFe3(BO3)(4) system
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2008. - Vol. 50, Is. 1. - P79-83. - ISSN 1063-7834, DOI 10.1134/S1063783408010150
Примечания : Cited References: 16
Предметные рубрики: IRON BORATE GDFE3(BO3)(4)
ND3+
Аннотация: The antiferromagnetic resonance in single crystals of the YFe3(BO3)(4)-GdFe3(BO3)(4) system is studied in the frequency range 25-140 GHz and the temperature range 4.2-50.0 K. It is established that the YFe3(BO3)(4) crystal containing only the magnetic subsystem of Fe3+ ions is an antiferromagnet with an easy anisotropy plane. The temperature dependences of the gaps in the antiferromagnetic resonance spectra of GdFe3(BO3)(4) and YxGd1-xFe3(BO3)(4) are used to calculate the contributions of the Fe3+ and Gd3+ subsystems to the magnetic anisotropy of these crystals. The contributions are found to be close in magnitude and have opposite signs. This leads to a relatively weak uniaxial anisotropy field in the crystals under investigation. Since the exchange interaction between the Gd3+ and Fe3+ ions magnetizes the magnetic subsystem of gadolinium, both subsystems start to contribute simultaneously at the Neel temperature of the iron subsystem.
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7.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Tugarinov V. I., Pankrats A. I., Kondyan S., Velikanov D. A., Temerov V. L.
Заглавие : Antiferromagnetic resonance and magnetic investigations of rare-earth ferroborates
Коллективы : Moscow International Symposium on Magnetism
Место публикации : Moscow Int. Symp. on Magnet. (MISM-2011): Book of abstracts. - 2011. - Ст.24OR-O-10. - P.623
Примечания : Библиогр.: 3. - Work is supported by RFBR grant 10-02-00765
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8.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Pankrats A., Petrakovskii G. A., Tugarinov V., Temerov V.
Заглавие : Antiferromagnetic resonance and phase diagram of HoFe3(BO3)4
Коллективы : Российская академия наук, Физико-технический институт им. А.Ф. Иоффе РАН, "Spin Waves", International Symposium
Место публикации : International Symposium "Spin waves - 2009": Saint Petersburg, Russia, June 7-12, 2009 : Simposium program. Abstracts. - 2009. - С. 40
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Pankrats A. I., Petrakovskii G. A., Bezmaternykh L. N., Bayukov O. A.
Заглавие : Antiferromagnetic resonance and phase diagrams of gadolinium ferroborate GdFe3(BO3)(4)
Разночтения заглавия :авие SCOPUS: Antiferromagnetic resonance and phase diagrams of gadolinium ferroborate GdFe3(BO3)4
Место публикации : J. Exp. Theor. Phys.: AMER INST PHYSICS, 2004. - Vol. 99, Is. 4. - P766-775. - ISSN 1063-7761, DOI 10.1134/1.1826168
Примечания : Cited References: 16
Ключевые слова (''Своб.индексиров.''): anisotropy--antiferromagnetic materials--antiferromagnetism--phase diagrams--resonance--single crystals--antiferromagnetic resonance--antiferromagnets--crystal axis--transition fields--gadolinium compounds
Аннотация: Antiferromagnetic resonance in single crystals of rhombohedral gadolinium ferroborate GdFe3(BO3)(4) was studied. The frequency-field dependences of antiferromagnetic resonance over the frequency range 26-70 GHz and the temperature dependences of resonance parameters for magnetic fields oriented along the crystal axis and in the basal plane were determined. It was found that the iron subsystem, which can be treated as a two-sublattice antiferromagnet with anisotropy of the easy-plane type, experienced ordering at T = 38 K. At temperatures below 20 K, the gadolinium subsystem with the opposite anisotropy sign strongly influenced the anisotropic properties of the crystal. This resulted in a spontaneous spin-reorientation transition from the easy-plane to the easy-axis state at 10 K. Below 10 K, magnetic field-induced transitions between the states were observed. Experimental phase diagrams on the temperature-magnetic field plane were constructed for fields oriented along the crystal axis and in the basal plane. A simple model was used to calculate the critical transition fields. The results were in close agreement with the experimental values measured at T = 4.2 K for both field orientations. (C) 2004 MAIK "Nauka / Interperiodica".
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Svistov L. E., Chubarenko V. A., Shapiro A. Y., Zalesskii A. V., Petrakovskii G. A.
Заглавие : Antiferromagnetic resonance in Bi2CuO4
Место публикации : J. Exp. Theor. Phys.: AMER INST PHYSICS, 1998. - Vol. 86, Is. 6. - P1228-1233. - ISSN 1063-7761, DOI 10.1134/1.558595
Примечания : Cited References: 14
Предметные рубрики: SINGLE-CRYSTAL
RANGE
Аннотация: Magnetic resonance of the low-frequency spin-wave branch in the Bi2CuO4 antiferromagnet with an easy-plane anisotropy has been studied. Angular, frequency, and temperature dependences of the position and width of the antiferromagnetic resonance (AFMR) line have been measured. Our measurements combined with earlier data [H. Ochta, K. Yoshida, T. Matsuya, T. Nanba, M. Motokawa, K. Yamada, Y. Endon, and S. Hosoya, J. Phys. Sec. Jpn. 61, 2921 (1992); E. W. Ong, G. H. Kwei, R. A. Robinson, B. L. Ramakrishna, and R. B. von Dreele, Phys. Rev. B 42, 4255 (1990)] have allowed us to determine anisotropy constants of this material and to account for the unusual character of its static susceptibility anisotropy. The AFMR line shifts to the high-field side and broadens in a temperature range of 10-15 K, and the cause of this has remained unclear. In the low-temperature range the line shows a hysteresis corresponding to a static field magnitude several times as large as the spin-flop field. The position and width of the AFMR line depend sensitively on the sample preparation technique. (C) 1998 American Institute of Physics.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bludov A. N., Pashchenko V. A., Kobets M. I., Bedarev V. A., Merenkov D. N., Gnatchenko S. L., Gudim I. A.
Заглавие : Antiferromagnetic resonance in crystalline PrFe3(BO3)4
Место публикации : Low Temp. Phys. - 2018. - Vol. 44, Is. 2. - P.139-143. - ISSN 1063-777X, DOI 10.1063/1.5020909. - ISSN 1090-6517(eISSN)
Примечания : Cited References: 18
Аннотация: Experimental AFMR studies of crystalline PrFe3(BO3)4 over a wide frequency range of 10–143 GHz at a temperature of 4.2 K have been carried out. The high-frequency properties of praseodymium ferroborate are well described in terms of a model of a two-sublattice antiferromagnet with an “easy axis” anisotropy. An energy gap of 134.3 ± 0.5 GHz is determined and the magnitude of the effective magnetic anisotropy field is estimated to be 1.9 ± 0.1 kOe. An analysis indicates that the spin-orientational phase transition in this compound is a first order transition.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kobets M.I., Dergachev K.G., Khatsko E.N., Gnatchenko S.L., Bezmaternykh L. N., Temerov V. L.
Заглавие : Antiferromagnetic resonance in ferroborate NdFe3(BO3)(4)
Место публикации : Physica B. - 2011. - Vol. 406, Is. 18. - P.3430-3435. - SEP 15. - ISSN 0921-4526, DOI 10.1016/j.physb.2011.06.014. - ISSN 1873-2135
Примечания : Cited Reference Count: 19
Предметные рубрики: Physics, Condensed Matter
Ключевые слова (''Своб.индексиров.''): antiferromagnet--resonance--multiferroics--commensurate-incommensurate phase
Аннотация: The AFMR spectra of the NdFe3(BO3)(4) crystal are measured in a wide range of frequencies and temperatures. It is found that by the type of its magnetic anisotropy the compound is an easy-plane antiferromagnet with a weak anisotropy in the basal plane. The effective magnetic parameters are determined: anisotropy fields H-a1 = 1.14 kOe and H-a2 = 60 kOe and magnetic excitation gaps Delta v(1) = 101.9 GHz and Delta v(2) = 23.8 GHz. It is shown that commensurate-incommensurate phase transition causes a shift in resonance field and a considerable change in absorption line width. At temperatures below 4.2 K nonlinear regimes of AFMR excitation at low microwave power levels are observed. (C) 2009 Elsevier B.V. All rights reserved.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kobets M. I., Dergachev K. G., Khatsko E. N., Gnatchenko S. L., Bezmaternykh L. N., Gudim, I. A.
Заглавие : Antiferromagnetic resonance study of the magnetic structure of Nd0.75Dy0.25Fe3(BO3)(4)
Место публикации : Low Temp. Phys.: American Institute of Physics, 2014. - Vol. 40, Is. 7. - P.629-634. - ISSN 1063-777X, DOI 10.1063/1.4890992. - ISSN 1090-6517
Примечания : Cited References: 17
Аннотация: The effect of replacing Nd3+ ions with Dy3+ ions on the resonance properties of Nd0.75Dy0.25Fe3(BO3)(4) is studied. The antiferromagnetic resonance (AFMR) method is used to detect an easy axis-easy plane magnetic spin-reorientation phase transition owing to competing exchange interactions of Nd-Fe and Dy-Fe, and the frequency-field dependence of the AFMR spectrum before and after the phase transition is studied. At 4.2 K, the detected resonance spectra in the H parallel to c direction are AFMR modes of iron, and their frequency-field dependences correspond to easy-axis (H 15 kOe) and easy-plane (H 16 kOe) magnetic structures with magnon excitation energy gaps of 77.2 and 100.3 GHz, respectively. The effective magnetic anisotropies responsible for these gaps are 0.7 and 1.2 kOe, respectively. Substitution by Dy3+ ions in crystalline Nd0.75Dy0.25Fe3(BO3)(4) in the paramagnetic region produces an additional static internal field owing to polarization, which leads to a shift in the resonance field of the EPR absorption line and a change in the g-factor of the Fe3+ ions. (C) 2014 AIP Publishing LLC.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : PETRAKOVSKII G. A., EMELYANOVA L. S., POZDNYAKOV V. G., KOROLEV V. K.
Заглавие : ANTIFERROMAGNETIC-RESONANCE OF LOW-DIMENSIONAL RB2MNXCD1-XCL4 ANTIFERROMAGNETS
Место публикации : Fiz. Tverd. Tela: MEZHDUNARODNAYA KNIGA, 1984. - Vol. 26, Is. 4. - P1200-1202. - ISSN 0367-3294
Примечания : Cited References: 5
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S.
Заглавие : Dimerization of antiferromagnetic chain with 4-spin interaction
Место публикации : Fiz. Tverd. Tela: MEZHDUNARODNAYA KNIGA, 1996. - Vol. 38, Is. 6. - P1868-1877. - ISSN 0367-3294
Примечания : Cited References: 30
Предметные рубрики: SPIN-1/2 HEISENBERG-ANTIFERROMAGNET
COMPETING INTERACTIONS
MONTE-CARLO
THERMODYNAMIC PROPERTIES
SYSTEMS
CUGEO3
TEMPERATURE
NEUTRON
STATE
MODEL
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S.
Заглавие : Existence of massive singlet excitations in an antiferromagnetic alternating chain with S=1/2
Место публикации : Phys. Rev. B: AMERICAN PHYSICAL SOC, 2000. - Vol. 61, Is. 10. - P6780-6784. - ISSN 1098-0121, DOI 10.1103/PhysRevB.61.6780
Примечания : Cited References: 26
Предметные рубрики: PEIERLS COMPOUND CUGEO3
SPIN SYSTEMS
TRANSITION
Аннотация: The one-dimensional Heisenberg model with alternating antiferromagnetic bond and spin-1/2 has been studied by the Monte Carlo method. The thermodynamic characteristics, spin-spin, and four spin-correlation function have been calculated. From several maxima of the correlation radius of the four spin-correlation function and sharp slopes of the dimer order parameter, a longitudinal component of the total spin square as a function of temperature and magnetic field, the existence of two mass singlet excitation branches with Delta S-z=0 and one triplet with Delta S-z=1 is suggested. Critical temperatures and fields related to singlet filled bands have been estimated. From these results low-temperature (TT-SP) properties of spin-Peierls (SP) compounds CuGeO3 and NaV2O5 have been explained.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S., Petrakovskii G. A.
Заглавие : Investigation of the magnetic properties of chains with alternating ferro- and antiferromagnetic exchange interactions in the Heisenberg model with spin S=1/2
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 1999. - Vol. 41, Is. 9. - P1511-1512. - ISSN 1063-7834, DOI 10.1134/1.1131042
Примечания : Cited References: 11
Предметные рубрики: HALDANE-GAP
SYSTEMS
Аннотация: The quantum Monte Carlo method is used to calculate the susceptibility and pairwise spin-spin correlation functions of chains with alternating ferro (K)- and antiferromagnetic (J)-exchange interactions within the Heisenberg model with spin S=1/2. From the susceptibility, the energy gap between the ground state and excited triplet states is determined for arbitrary ratios K/J. The value of the gap coincides with the Haldane gap for spin S=1 when K/J 1.25. (C) 1999 American Institute of Physics. [S1063-7834(99)02409-0].
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S.
Заглавие : Nonadiabatic interaction of acoustic phonons with spins S=1/2 in the two-dimensional Heisenberg model
Разночтения заглавия :авие SCOPUS: Nonadiabatic interaction of acoustic phonons with spins S = 1/2 in the two-dimensional heisenberg model
Место публикации : J. Exp. Theor. Phys.: AMER INST PHYSICS, 2003. - Vol. 97, Is. 5. - P969-977. - ISSN 1063-7761, DOI 10.1134/1.1633952
Примечания : Cited References: 18
Предметные рубрики: QUANTUM MONTE-CARLO
EU2CUO4
GD2CUO4
POLARON
Ключевые слова (''Своб.индексиров.''): antiferromagnetic materials--correlation methods--crystal symmetry--magnetic couplings--magnetic moments--magnetization--monte carlo methods--quantum theory--acoustic phonons--nonadiabatic interaction--orthorhombicity--quantum spin liquid transitions--phonons
Аннотация: The ground state of a two-dimensional antiferromagnet having spins S = 1/2 and interacting with acoustic phonons is investigated in the nonadiabatic approximation using the quantum-mechanical Monte Carlo method. The critical parameters of the spin-phonon coupling, corresponding to the formation of bound spin-phonon excitations, crystal symmetry lowering, and the emergence of a gap in the spin excitation spectrum, as well as the antiferromagnet-quantum spin liquid transition, are determined. The orthorhombicity parameter, the sublattice magnetization, the violation of the spherical symmetry of spin-spin correlation functions, and the magnetic moment in Gd2CuO4 and Eu2CuO4 are calculated. (C) 2003 MAIK "Nauka / Interperiodica".
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S.
Заглавие : Quantum Monte Carlo investigation of the magnetic properties of weakly interacting antiferromagnetic chains with an alternating exchange interaction with spin S=1/2
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2000. - Vol. 90, Is. 1. - P194-201. - ISSN 1063-7761, DOI 10.1134/1.559075
Примечания : Cited References: 35
Предметные рубрики: PEIERLS COMPOUND CUGEO3
MAGNON DISPERSION
BI2CUO4
EXCITATIONS
RESONANCE
SYSTEMS
SCATTERING
DYNAMICS
NEUTRON
PHASE
Аннотация: An approximation dependence of the spontaneous magnetic moment at a site, sigma/sigma(0) - 1 = 0.71(6)delta(2.5(2)), and the antiferromagnet-singlet state phase boundary, J(2)/J(1) = 0.52(3)delta, are determined by the quantum Monte Carlo method in the self-consistent sublattice molecular field approximation for weakly interacting (J(2)) antiferromagnetic chains with spin S = 1/2 and alternating exchange interaction (J(1) +/- delta). The Neel temperature and a number of critical temperatures which could be related with the filling energy of two singlets (Delta S-z = 0) and one triplet (Delta S-z= 1) spin bands, each of which is split by the sublattice field (h(x,y)not equal h(z)) into two subbands, are determined on the basis of the computed correlation radii of the two- and four-spin correlation function, the squared total spin (S-z)(2) with respect to the longitudinal components, the dimerization parameter, and the correlation functions between the nearest neighbors with respect to longitudinal and transverse spin components. On the basis of the Monte Carlo calculations, the critical temperatures and possible energy gaps at the band center are determined for the antiferromagnets CuWO4 and Bi2CuO4 and for the singlet compounds (VO)(2)P2O7 and CuGeO3 , agreeing satisfactorily with existing results, and new effects are also predicted. (C) 2000 MAIK "Nauka / Interperiodica".
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S., Petrakovskii G. A., Miroshnichenko N. I.
Заглавие : Simulation of magnetic properties of the two-dimensional magnetic with anisotropic antiferromagnetic interactions and cluster ordering by quantum Monte Carlo
Место публикации : Phys. Lett. A: ELSEVIER SCIENCE BV, 2008. - Vol. 372, Is. 26. - P4722-4725. - ISSN 0375-9601, DOI 10.1016/j.physleta.2008.05.010
Примечания : Cited References: 12
Предметные рубрики: SPIN SYSTEM
EXCITATIONS
CU3B2O6
MODEL
Ключевые слова (''Своб.индексиров.''): anisotropic antiferromagnetic--cluster ordering--plateau of magnetization--modulated structure--exchange in cu3b2o6--anisotropic antiferromagnetic--cluster ordering--exchange in cu3b2o6--modulated structure--plateau of magnetization
Аннотация: Magnetic with anisotropic anti ferromagnetic exchange interactions and special topology of coupling in the square lattice with spins pairs ordering is studied by quantum Monte Carlo method. The antiferromagnetic order is found to be more stable as compared to spin liquid state. Exchange interactions and wave vector of structure modulation for Cu3B2O6 is estimated. Neel temperature versus strength of exchange in spin pair is calculated. Plateau and modulation of magnetic structure in field magnetization dependence is revealed. (C) 2008 Elsevier B.V. All rights reserved.
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