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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Назаренко, Илья Иванович, Софронова, Светлана Николаевна
Заглавие : Теоретико-групповой анализ возможных магнитных структур твердого раствора NI5GEO4(BO3)2
Место публикации : Вестник СибГАУ. - 2013. - № 1. - С. 63-68
Ключевые слова (''Своб.индексиров.''): магнетизм--теоретико-групповой анализ--людвигиты--magnetism--group-theoretical--ludwigites
Аннотация: Проведен симметрийный анализ возможных магнитных структур кристалла Ni5GeO4(BO3)2, возникающих в результате фазовых переходов. Получены базисные функции неприводимых представлений, входящих в магнитное представление этой структуры, показывающие вероятные направления магнитных моментов атомов Ni5GeO4(BO3)2. Полученные результаты помогут интерпретации экспериментальных данных при установлении истинной магнитной структуры и механизмов магнитных переходов в исследуемом соединении.The work presents a group-theoretical analysis which makes possible to determine Ni5GeO4(BO3)2 crystal potential magnetic structures. The obtained information will help to analyze and interpret experimental data, while determining the true magnetic structure and the mechanisms of magnetic transitions in the compound being tested.
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bartolome J., Arauzo A., Kazak N. V., Ivanova N. B., Ovchinnikov S. G., Knyazev Yu. V., Lyubutin I. S.
Заглавие : Uniaxial magnetic anisotropy in Co2.25Fe0.75O2BO3 compared to Co3O2BO3 and Fe3O2BO ludwigites
Разночтения заглавия :авие SCOPUS: Uniaxial magnetic anisotropy in Co2.25Fe0.75O 2BO3 compared to Co3O2BO3 and Fe3O2BO ludwigites
Место публикации : Phys. Rev. B: AMER PHYSICAL SOC, 2011. - Vol. 83, Is. 14. - Ст.144426. - ISSN 1098-0121, DOI 10.1103/PhysRevB.83.144426
Примечания : Cited References: 25. - The authors acknowledge V. V. Rudenko for the oxyborate samples they made and O. A. Bayukov for fruitful discussion. The financial support of Spanish MINCYT, Grant No. MAT08/1077, and the Aragonese E-34 project are acknowledged. Fruitful discussions with F. Bartolome and P. Bordet are acknowledged. The latter is thanked for providing the FeINF3/INFOINF2/INFBOINF3/INF single crystal. Also this study was supported by the Russian Foundation for Basic Research (Project No. 09-02-00171-a), the Federal Agency for Science and Innovation (Rosnauka) (Project No. MK-5632.2010.2), and the Physical Division of the Russian Academy of Science (Program "Strongly Correlated Electrons," Project No. 2.3.1).
Предметные рубрики: CRYSTAL-STRUCTURE
MOSSBAUER
CO3BO5
Аннотация: Magnetic and Mossbauer spectroscopy (MS) measurements have been performed on a single crystal of Co2.25Fe0.75O2BO3 with ludwigite structure. Two magnetic transitions (T-N = 115 K and T-C = 70 K) were traced from the ac susceptibility temperature dependence. The MS spectra as a function of temperature clearly show the onset of magnetic ordering below 115 K. Magnetization measurements on the parent Co3O2BO3 and Fe3O2BO3 compounds have been done for comparison. In Fe3O2BO3 the anisotropy of the different phases has been determined, showing that the anisotropy axis changes from the a to the b axis in the low-temperature antiferromagnetic phase. High magnetic uniaxial anisotropy has been detected for both Co3O2BO3 and Co2.25Fe0.75O2BO3. From the angle-dependent magnetization measurements it is found that in both compounds the easy axis of magnetization is the b [010] axis, where an antiferromagnetic component is superimposed on the main ferromagnetic component. In the c direction the behavior is purely antiferromagnetic. In Co2.25Fe0.75O2BO3 a strong reduction of the remanent magnetization and a very strong increase in coercive field along the b axis with respect to those found in Co3O2BO3 were observed from magnetic hysteresis cycles measured below T-C. The increase of coercive field is caused by the increase of defects upon Co substitution by Fe.
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Moshkina E. M., Platunov M. S., Seryotkin Y. V., Bovina A. F., Eremin E. V., Sofronova S. N., Bezmaternykh L. N.
Заглавие : Transformation of structure and magnetic properties of Cu2MnBO5 under partial Mn3+ → Fe3+ substitution
Место публикации : J. Magn. Magn. Mater. - 2018. - Vol. 464. - P.1-10. - ISSN 03048853 (ISSN), DOI 10.1016/j.jmmm.2018.05.021
Примечания : Cited References: 25. - This study was supported by Russian Foundation for Basic Research ( RFBR ) and Government of Krasnoyarsk Territory according to the research project No. 16-42-243028. X-ray diffraction experiment was carried out at the Centre on Molecular Design and Ecologically Safe Technologies at the Novosibirsk State University. The work of one of the coauthors (M.S.P.) was supported by the Russian Foundation for Basic Research (project no. 16-32-60049) and by the program of Foundation for promoting the development of small enterprises in scientific and technical sphere (“UMNIK” program).
Ключевые слова (''Своб.индексиров.''): ludwigites--crystal growth--ferrimagnets--quasi-low-dimensional structure--magnetic phase transitions
Аннотация: Single crystals of Fe-substituted Cu2Mn1-xFexBO5 ludwigites have been synthesized using flux technique (x = 0.2, 0.4, 0.5 – in the initial flux system). Structural properties of the synthesized compounds were studied by the single crystal and powder X-ray diffraction analysis. Obtained results were analyzed in the relationship with parent compound Cu2MnBO5. It was revealed that the type of monoclinic distortions of Fe-substituted ludwigites is different from the structure of Cu2MnBO5. The real cation composition and local structure of Cu2Mn1-xFexBO5 ludwigites were studied using XANES and EXAFS techniques, respectively. Analysis of field and thermal dependencies of magnetization showed a high dependence of the magnetic properties of these ludwigites on x with changing the type of magnetic ordering.
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sofronova S. N., Bezmaternykh L. N., Eremin E. V., Nazarenko I. I., Volkov N. V., Kartashev A. V., Moshkina E. M.
Заглавие : The superexchange interactions and magnetic ordering in low-dimentional ludwigite Ni5GeB2O10
Место публикации : J. Magn. Magn. Mater.: Elsevier, 2016. - Vol. 401. - P.217-222. - ISSN 0304-8853, DOI 10.1016/j.jmmm.2015.10.024
Примечания : Cited References: 23. - This study was supported by Russian Foundation for Basic Research (RFFI Siberia No. 15-42-04186). We thank S. Popkov, G. Yurkin for help on the magnetic measurements and M.S. Molokeev for help on the x-ray diffraction
Предметные рубрики: DIELECTRICS
EXCHANGE
CATION
Ключевые слова (''Своб.индексиров.''): ludwigites--magnetic order--heat capacity--exchange interactions--ferrimagnetic
Аннотация: The ludwigite Ni5Ge(BO5)2 belongs to a family of oxyborates which have low-dimensional subunits in the form of three-leg ladders unit structure. This material was studied by magnetic and thermodynamic measurements. Ni5Ge(BO5)2 does not show full long-range magnetic order, but one goes into a partial ordering or spin-glass state at 87 K. The superexchange interactions were calculated in the framework of a simple indirect coupling model. Different models of magnetic structure of Ni5Ge(BO5)2 and its unique magnetic behaviour was discussed. © 2015 Elsevier B.V.
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sofronova S. N., Eremin E. V., Moshkina E. M., Selyanina A. V., Bondarenko G. N., Shabanov A. V.
Заглавие : Synthesis, structural and magnetic properties of ludwigite Mn1.32Ni0.85Cu0.83BO5
Место публикации : Phys. Solid State. - 2022. - Vol. 64, Is. 11. - P.1743-1749. - ISSN 10637834 (ISSN), DOI 10.21883/PSS.2022.11.54200.425. - ISSN 10906460 (eISSN)
Примечания : Cited References: 19. - The study was done with financial support from the Russian Foundation for Basic Research, Government of Krasnoyarsk Territory and the Krasnoyarsk Regional Fund of Science within scientific project No. 20-42-240011. The research was carried out using the equipment provided by the Krasnoyarsk Regional Center for Collective Use
Аннотация: Single crystals of Mn1.32Ni0.85Cu0.83BO5 with the ludwigite structure were obtained by the solution-melt method during spontaneous crystallization. The concentration of copper, manganese and nickel ions was determined by transmission microscopy. Manganese ions are included in compounds in the divalent and trivalent states. The study of temperature and field dependences showed that we have several magnetic transitions. The first transition, associated with the ferrimagnetic ordering of the magnetic moments of parts of the ions, observed in the region of 50 K. In the region of 25 K, a second magnetic transition is observed. Substitution of nickel ions for copper and divalent manganese of better disorder and competition of exchange interactions, which leads to the division of the magnetic system into several magnetic subsystems that are ordered at different temperatures.
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Eremina R. M., Gavrilova T. P., Moshkina E. M., Gilmutdinov I. F., Batulin R. G., Gurzhiy V. V., Grinenko V., Inosov D. S.
Заглавие : Structure, magnetic and thermodynamic properties of heterometallic ludwigites: Cu2GaBO5 and Cu2AlBO5
Место публикации : J. Magn. Magn. Mater. - 2020. - Vol. 515. - Ст.167262. - ISSN 03048853 (ISSN), DOI 10.1016/j.jmmm.2020.167262
Примечания : Cited References: 42. - The reported study was supported by the Russian Foundation for Basic Research (RFBR), grant No 17-02-00953. T.P.G., R.M.E. acknowledge the financial support from the government assignment for FRC Kazan Scientific Center of RAS. D.S.I. acknowledges funding from the German Research Foundation through the Collaborative Research Center SFB 1143 in Dresden (project C03) and the Würzburg-Dresden Cluster of Excellence on Complexity and Topology in Quantum Matter – ct.qmat (EXC 2147, project-id 39085490). The XRD and EDX measurements have been performed at the X-ray Diffraction Centre and Centre for Microscopy and Microanalysis of the St. Petersburg State University. The magnetometer studies were performed by the subsidy allocated to Kazan Federal University for the state assignment in the sphere of scientific activities (Project No. 0671-2020-0050)
Аннотация: +We present an extensive study of the structural, magnetic and thermodynamic properties of high-quality monocrystals of two heterometallic oxyborates from the ludwigite family: Cu2GaBO5 and Cu2AlBO5 in the temperature range above 2 K. The distinctive feature of the investigated structures is the selective distribution of Cu and Ga/Al cations. The unit cell of Cu2GaBO5 and Cu2AlBO5 contains four nonequivalent crystallographic sites of metal ions. Two sites in the structure of Cu2GaBO5 are fully occupied by Cu atoms which form the quasi one-dimensional chains along the a-axis. For Cu2AlBO5 all sites are partially occupied by Al and Cu atoms. The joint analysis of low-temperature data on magnetic susceptibility and magnetic contribution to the specific heat showed that Cu2AlBO5 and Cu2GaBO5 exhibit an antiferromagnetic transition at TN=2.4 and 4.1 K, respectively. The magnetic response below TN can be represented as the sum of two contributions: the ordered component and the paramagnetic contribution from defects of the same relative weight. It is shown that the external magnetic field above 2.5 T and 2.8 T for Cu2GaBO5 and Cu2AlBO5, respectively, leads to a broadening of the magnetic phase transition indicating suppression of the long-range antiferromagnetic order.
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ivanova N. B., Kazak N. V., Knyazev Yu.V., Velikanov D. A., Vasil'ev A. D., Bezmaternykh L. N., Platunov M. S.
Заглавие : Structure and magnetism of copper substituted cobalt ludwigite Co3O2BO3
Место публикации : Физ. низких температур. - 2013. - Т. 39, Вып. 8. - P.913-918; Fiz. Nizk. Temp. - 2013. - Vol. 39, Is. 8. - P.913-918
Ключевые слова (''Своб.индексиров.''): transition metal ludwigites--ferrimagnetism--magnetic hysteresis--людвигиты переходных металлов--ферримагнетизм--магнитный гистерезис
Аннотация: The single crystals Co3O2BO3 with partial (4%) substitution of Co by Cu ions were synthesized by the flux technique. X-ray diffraction and magnetic properties investigations were carried out. The x-ray diffraction meas-urements have shown that Cu clearly prefers only one from four nonequivalent crystallographic positions with the smallest electric field gradient. The ferrimagnetic ordering near TN = 43 K and high magnetic hardness in this magnetic phase are similar to Co3O2BO3. The small reduction of the effective magnetic moment was revealed under copper substitution.Монокристаллы кобальтового людвигита с частичным (4%) замещением кобальта Со медью Cu были синтезированы раствор-расплавным методом. Были проведены рентгено-структурный анализ и измерение магнитных свойств. Рентгеновские измерения показывают, что медь явно предпочитает только одно от четырех неэквивалентных кристаллографических положений с самым маленьким градиентом электрического поля. Ферримагнетик, упорядочивающийся около TN = 43 K, с высокой магнитной твердостью - в этом магнитная фаза подобна Co3O2BO3. Показано, что при замещении медью проявляется небольшое сокращение эффективного магнитного момента.
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Moshkina E. M., Eremin E. V., Velikanov D. A., Bovina A. F., Molokeev M. S., Seryotkin Y., Cherosov M., Batulin R., Nemtsev I. V., Bezmaternykh L. N.
Заглавие : Structural and magnetic alteration of Cu2GaBO5 forced by Mn3+ doping
Коллективы : Russian Science FoundationRussian Science Foundation (RSF) [21-72-00130]; Kazan Federal University [0671-2020-0 050]
Место публикации : J. Alloy. Compd. - 2022. - Vol. 902. - Ст.163822. - ISSN 0925-8388, DOI 10.1016/j.jallcom.2022.163822. - ISSN 1873-4669(eISSN)
Примечания : Cited References: 43. - The study was supported by the Russian Science Foundation (Grant No. 21-72-00130) . The specific heat measurements were supported by the subsidy allocated to Kazan Federal University for the state assignment in the sphere of scientific activities (Project No.Journal of Alloys and Compounds 902 (2022) 163822 0671-2020-0 050) . The magnetic measurements, powder X-ray and EDX data were obtained using the analytical equipment of Krasnoyarsk Regional Center of Research Equipment of Federal Research Center "Krasnoyarsk Science Center SB RAS". The X-ray single-crystal experiment was done using the equipment of the Research and Education Centre "Molecular Design and Environmentally Safe Technologies" at NSU. The authors acknowl-edge Prof. Rushana Eremina and Dr. Tatyana Gavrilova for the valu-able discussion of the obtained results
Предметные рубрики: CRYSTAL-STRUCTURE
SUSCEPTIBILITY
Аннотация: To study the gradual change of the structure and the magnetic state of the ludwigite Cu2GaBO5 upon Mn3+ doping, single crystals of Cu2Ga1−xMnxBO5 (x = 0.55, 0.7, 0.8) with the size up to 3 × 3 × 10 mm3 were grown using the flux technique. The phase homogeneity and crystal structure of the obtained compounds were investigated by the powder and single crystal X-ray diffraction. All the samples possessed the monoclinic-distorted ludwigite structure with the P21/c space group. The study of the actual Cu/Ga/Mn composition by the EDX (energy-dispersive X-ray spectroscopy) technique revealed the lower Mn content in all the samples and the refined formulas were Cu2Ga0.47Mn0.53BO5, Cu1.92Ga0.5Mn0.58BO5 and Cu2Ga0.32Mn0.68BO5, respectively. Despite the high manganese content, the concentration transition (from Cu2GaBO5 to Cu2MnBO5) and change of the monoclinic angle did not occur, but strong Me-O octahedra distortions exceeding those both in the parent ludwigites Cu2GaBO5 and Cu2MnBO5 were found. The study of the thermodynamic and magnetic properties revealed the low-temperature magnetic phase transition inherited from the parent Cu2GaBO5 in all the samples. However, the nature and ordering type for the compounds with different Mn content were different: there was a complex transformation of the magnetic state from the partially ordered AFM (antiferromagnetically) in Cu2Ga0.47Mn0.53BO5, through the spin glass state, to the combined spin glass/ordered state in Cu2Ga0.32Mn0.68BO5 with the appearance of magnetic anisotropy. The evident dependence of Tc (phase transition temperature) on the magnetic field was found as well as its decrease at the nonzero magnetic field in the samples with x = 0.53 and 0.68.
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bezmaternykh L. N., Moshkina E. M., Eremin E. V., Molokeev M. S., Volkov N. V., Seryotkin Yu. V.
Заглавие : Spin-lattice coupling and peculiarities of magnetic behavior of ferrimagnetic ludwigites Mn0.52+M1.52+Mn3+BO5(M=Cu, Ni)
Коллективы : Moscow International Symposium on Magnetism
Место публикации : Solid State Phenom.: Selected, peer reviewed papers/ ed.: N. Perov, A. Semisalova: Trans Tech Publications Ltd, 2015. - Vol. 233-234: Achievements in Magnetism. - P.133-136. - ISSN 1662-9779, DOI 10.4028/www.scientific.net/SSP.233-234.133. - ISSN 978-3-03835-482-6
Примечания : Cited References: 7
Предметные рубрики: Achievements in magnetism
Ключевые слова (''Своб.индексиров.''): counter magnetization--spin-lattice coupling--ludwigites
Аннотация: Temperature-field and orientational magnetization dependences of single crystals were measured. Both samples demonstrate significant field-depending temperature hysteresis and low-temperature counter field magnetization. The correlation of orientational dependences of these effects and magnetic anisotropy is analyzed; the role of spin-lattice interactions is discussed.Измерены температурно-полевые и ориентационные зависимости намагниченности монокристаллов. Оба образца демонстрируют гистерезис температуры в зависимости от поля и существенную намагниченность, направленную против поля при низкой температуре. Анализируется корреляция ориентационных зависимостей этих эффектов и магнитной анизотропии; Обсуждается роль спин-решеточных взаимодействий.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ivanova N. B., Platunov M. S., Knyazev Yu. V., Kazak N. V., Bezmaternykh L. N., Eremin E. V., Vasiliev A. D.
Заглавие : Spin-glass magnetic ordering in CoMgGaO2BO3 ludwigite
Место публикации : Физ. низких температур: Физико-технический институт низких температур им. Б.И. Веркина НАН Украины, 2012. - Т. 38, Вып. 2. - С.214-217. - ISSN 0132-6414. - ISSN 1816-0328
Примечания : Библиогр.: 13 назв. - This work was supported by the Russian Foundation for Basic Research (project No. 09-02-00171-a), the Federal Agency for Science and Innovation (Rosnauka) (project No. MK-5632.2010.2), the Physics Division of the Russian Academy of Sciences, the program "Strongly Correlated Electrons" (project 2.3.1).
Предметные рубрики: AC Magnetic susceptibility
DC magnetization
Field cooled
Flux methods
Frequency dependent
Magnetic system
Magnetic transitions
Needle shape
Parent compounds
Spin-glasses freezing
Temperature dependencies
Unit-cell volume
Zero-field-cooled
Cobalt
Cobalt compounds
Freezing
Glass
Magnetic susceptibility
Magnetism
Single crystals
X-ray diffraction
Spin glass
Ключевые слова (''Своб.индексиров.''): spin-glass freezing--transition metal ludwigites
Аннотация: The single crystal needle shape samples of diamagnetically diluted cobalt ludwigite CoMgGaO2BO3 have been grown by the flux method. The results of x-ray diffraction and both dc and ac magnetic measurements are presented. The unit cell volume undergoes a noticable growth under dilution from 328.31 Å3 for the parent compound Co3O2BO3 to 345.46 Å3 for CoMgGaO2BO3. The temperature of magnetic transition is considerably lower for the latter compound (25 K against 43 Kfor Co3O2BO3). The dc magnetization temperature dependencies undergo the splitting of field cooled and zero-field cooled regimes and the ac magnetic susceptibility temperature dependencies are frequency dependent pointing out a possible spin-glass freezing in the magnetic system.
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