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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Krasikov A. A., Knyazev Yu. V., Yaroslavtsev R. N., Velikanov D. A., Mikhlin Yu. L., Volochaev M. N., Bayukov O. A., Ladygina V. P., Stolyar S. V., Iskhakov R. S.
Заглавие : Magnetic collective state formation upon tuning the interparticle interactions in ensembles of ultrafine ferrihydrite nanoparticles
Колич.характеристики :13 с
Место публикации : Nano-Struct. Nano-Objects. - 2024. - Vol. 37. - Ст.101089. - ISSN 2352507X (ISSN), DOI 10.1016/j.nanoso.2023.101089. - ISSN 23525088 (eISSN)
Примечания : Cited References: 93. - The authors thank M.N. Volochaev for the TEM investigations
Аннотация: The results of a study of the dynamic (alternating current magnetic susceptibility) and static magnetic properties, as well as 57Fe Mössbauer spectrometry and ferromagnetic resonance of two-line ferrihydrite nanoparticle systems with varying intensities of magnetic interparticle interactions are reported. The strength of the magnetic interparticle interactions has been tuned by coating (with various degrees of coating) the ferrihydrite particles (2–4 nm in size and an average size ∼2.7 nm) of the initial synthetic sample by arabinogalactan. Also, a biogenic ferrihydrite sample (an average particle size of 2-nm) with a natural organic coating was studied and it has the weakest magnetic interparticle interactions among of all the samples. Relaxation times of the particle’s magnetic moment were determined by the data of static and dynamic magnetic susceptibilities and from analysis of 57Fe Mössbauer spectrometry. Based on the temperature dependences of the relaxation times, it has been concluded that the predominantly collective processes of freezing of the particle magnetic moments occur under the action of the magnetic interparticle interactions. It is shown that an important role in these processes is played by a magnetic subsystem of the surface spins of the particles. The effect of the interplay between the surface spin and magnetic moment subsystems on the static magnetic properties (low-temperature magnetic hysteresis loops) and the parameters of the microwave absorption line under the magnetic resonance conditions is discussed.
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Вид документа : Статья из журнала
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Автор(ы) : Sofronova S. N., Chernyshev A.
Заглавие : Magnetic ordering and the role of superexchange Ni–O–B–O–Ni upon the formation of magnetic order in ludwigite Ni2MnBO5 from first-principal calculations
Место публикации : Comput. Condens. Matter. - 2024. - Vol. 40. - Ст.e00918. - ISSN 23522143 (eISSN), DOI 10.1016/j.cocom.2024.e00918
Примечания : Cited References: 28
Аннотация: The energies of various magnetically ordered structures for ludwigite Ni2MnBO5 have been calculated in the framework of the first-principles approach using the Wien2K program package, with the parameters of exchange interactions being determined. Two subsystems can be distinguished in the magnetic system, which are associated with the triads 4-2-4 and 3-1-3. The magnetic moments of the ions in both triads are antiferromagnetically oriented. The analysis of the exchange contribution to the energy shows that there occurs an increase of the magnetic cell relative to the crystallographic one due to antiferromagnetic ordering of the magnetic moments along the c axis in three-legged ladders formed by 4-2-4 triads. However, in three-legged ladders formed by 3-1-3 triads, the magnetic moments of the ions are ordered along the c-axis ferromagnetically. The predicted type of magnetic ordering in Ni2MnBO5 is similar to magnetic ordering in Fe3BO5. Non-collinear ordering of the magnetic moments of the subsystems at different temperatures is also likely to be observed in Ni2MnBO5, as is the case in Fe3BO5. Superexchange (indirect) interactions (No-O-B-O-Ni) influence the orientation of the magnetic moments of two 3-1-3 (4-2-4) triads within the unit cell. It is these interactions that may be responsible for the formation of long-range magnetic order in Co3BO5 and ferrimagnetic-antiferromagnetic spin-reorientation transition in Fe3BO5.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Krasikov A. A., Knyazev Yu. V., Balaev D. A., Velikanov D. A., Stolyar S. V., Mikhlin Yu. L., Yaroslavtsev R. N., Iskhakov R. S.
Заглавие : Interparticle magnetic interactions and magnetic field dependence of superparamagnetic blocking temperature in ferrihydrite nanoparticle powder systems
Место публикации : Phys. B: Condens. Matter. - 2023. - Vol. 660. - Ст.414901. - ISSN 09214526 (ISSN), DOI 10.1016/j.physb.2023.414901. - ISSN 18732135 (eISSN)
Примечания : Cited References: 66. - This study was supported by his work was supported by the Russian Science Foundation, project no. 22-72-00134
Аннотация: In this study, nanoparticles of initial synthetic ferrihydrite have been coated with arabinogalactan. The synthesized series of samples with different degrees of coverage of particles has been characterized by X-ray photoelectron spectroscopy, Mossbauer spectroscopy, transmission electron microscopy and magnetometry. The superparamagnetic blocking temperature decreases monotonically with an increase in the degree of coverage of ferrihydrite particles, which is unambiguously related to the different role of the interparticle magnetic interactions in the investigated powder systems. Analysis of the field dependence of the blocking temperature within the random anisotropy model has shown that an increase in the degree of coverage of ferrihydrite particles leads to a decrease in the size of a cluster in which the behaviors of the nanoparticle magnetic moments are correlated. The results obtained have shown the possibility of effective control of the strength of magnetic interparticle interactions in powder ferrihydrite systems by coating nanoparticles with arabinogalactan.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sofronova S. N., Eremin E. V., Veligzhanin A. A., Chernyshov A. V., Kartashev A. V., Velikanov D. A.
Заглавие : Magnetic transitions and different valence states of manganese ions in solid solutions (Ni,Cu,Mn)3BO5
Место публикации : Phys. Solid State. - 2023. - Vol. 65, Is. 2. - P.260-269. - ISSN 10637834 (ISSN), DOI 10.21883/PSS.2023.02.55410.512. - ISSN 10906460 (eISSN)
Примечания : Cited References: 22. - 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
Аннотация: The content of metal ions and their valence state for three NixCuyMn3–x–yBO5 compositions were estimated by EXAFS and XANES spectroscopy methods. In all three compositions, the copper y content did not exceed 0.25; in the third composition, some manganese ions entered the compound not only in the trivalent, but also in the divalent state. A detailed study of the magnetic properties showed that two magnetic transitions are observed in all compositions: one in the region of 60–75 K, and the second in the region of 10 K. Based on the exchange interactions calculated within the framework of the empirical model, the magnetic ordering temperatures for two- and three-lattice magnets were determined and it was assumed that the magnetic transition in the region of 60–75 K is associated with the ordering of magnetic moments in positions 2 and 3.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sofronova S. N., Veligzhanin, Aleksey, Eremin E. V., Chernyshev A. V., Kartashev A. V., Velikanov D. A.
Заглавие : Possible noncollinear magnetism and different valence state of manganese ions in quasi-low-dimensional ludwigites of (Ni,Cu,Mn)3BO5
Место публикации : Phys. Status Solidi B. - 2023. - Vol. 260, Is. 5. - Ст.2200457. - ISSN 03701972 (ISSN), DOI 10.1002/pssb.202200457. - ISSN 15213951 (eISSN)
Примечания : Cited References: 30. - The equipment of Krasnoyarsk Regional Center of Research Equipment of Federal Research Center “Krasnoyarsk Science Center SB RAS” was used for measurements in this research. The authors thank E. Moshkina for providing the samples for the studyKrasnoyarsk Territorial Foundation for Support of Scientific and R&D Activity. Grant Number: 20-42-240011
Аннотация: The content of transition-metal ions and their valence state for three compositions of NixCuyMn3−x−yBO5 are estimated by the methods of X-ray absorption spectroscopy. In all the three compositions, the copper content does not exceed 0.25. One of the compositions has manganese ions both in the trivalent and bivalent states according to the K-edge position. The calculations of the total energies of various cation-ordered structures using the software package Wien2K show that copper ions predominately occupy one site, namely, 2(2d). The measurements of the magnetic properties show two types of magnetic transitions in all the three compositions, with one of them being in the range of 60–75 K and the other one at 10 K. Based on the exchange interactions calculated in the framework of the empirical model, magnetic ordering temperatures are estimated for two- and three-sublattice structures and the magnetic transition in the range of 60–75 K is supposed to be connected with magnetic moment ordering in sites 2 and 3.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Yang, Zhiyu, Zhao, Yifei, Ueda, Jumpei, Molokeev M. S., Shang, Mengmeng, Xia, Zhiguo
Заглавие : Engineering charge-transfer interactions for red-emitting SrLa(Sc,Ga)O4:Ce3+ phosphor with improved thermal stability
Место публикации : Sci. China Mater. - 2023. - Vol. 66, Is. 5. - P.1989-1996. - ISSN 20958226 (ISSN), DOI 10.1007/s40843-022-2315-9. - ISSN 21994501 (eISSN)
Примечания : Cited References: 32. - This work was supported by the National Key Research and Development Program of China (2021YFE0105700), the National Natural Science Foundations of China (51972118), the Natural Science Foundation of Shandong Province (ZR2021ZD10 and ZR2018JL016), Guangzhou Science & Technology Project (202007020005), and the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program (2017BT01X137). This work was also funded by Russian Foundation for Basic Research (19-52-80003)
Аннотация: Blue-light-excitable red-emitting phosphors with high thermal stability are essential for fabricating white light-emitting diodes (WLEDs). Herein, Ce3+-doped SrLaScO4 (SLO:Ce3+) phosphor is discovered to have an abnormal red emission band centered at 640 nm when excited at 440 nm. Spectroscopy and structural analyses confirm that Ce3+ ions occupy the [LaO8] polyhedrons competitively, generating a strong crystal field splitting and a large Stokes shift to produce a red emission. To further restrict the thermal quenching of SLO:Ce3+, charge-transfer engineering is implemented by incorporating a large electronegative Ga3+ in the Sc3+ site, which can attract more charges from nearby coordinating groups to decrease the electronic occupation at the bottom of the conduction band and thereby enlarge the band gap. Sc/Ga substitution in SrLa(Sc,Ga)O4:Ce3+ enhances the thermal stability by increasing the intensity ratio from 15% to 31% at 150°C compared with 20°C. This is attributed to the efficient suppression of the thermally stimulated ionization process. This study presents a general design principle for discovering novel Ce3+-doped red phosphors with good thermal stability for WLED applications.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Klyuchantsev A. B., Dzebisashvili D. M.
Заглавие : Quantum transport via dot devices with arbitrarily strong interactions
Колич.характеристики :22 с
Место публикации : Phys. Scr. - 2023. - Vol. 98, Is. 3. - Ст.035811. - ISSN 00318949 (ISSN), DOI 10.1088/1402-4896/acb61e. - ISSN 14024896 (eISSN)
Примечания : Cited References: 49. - The authors would like to thank V V Val'kov and S.V. Aksenov for fruitful discussions
Аннотация: The paper develops a theory of tunneling electron transport through atomic-scale systems (or briefly quantum dots) with arbitrarily strong interaction. The theory is based on a diagram technique for nonequilibrium Green’s functions defined on Hubbard operators. The use of Hubbard operators, describing many-body states of an entire quantum dot, makes it possible to represent the Hamiltonian of the quantum dot in a universal diagonal form and consider its coupling with two leads within the perturbation theory. It is shown that in the case when all Hubbard operators are defined for the same site, some rules of the diagram technique for Hubbard operators, initially developed for lattice models, have to be modified. As an example of the application of the modified theory, the current-voltage characteristics of the single-impurity Anderson model with infinitely large Coulomb repulsion are calculated. It is shown that taking into account the multiple electron tunneling processes with spin flips results in the dip in the center of the Lorentz distribution peak, describing the density of states of the one level Anderson impurity coupled with two leads. The emergence of this dip in the density of states leads to a peculiar feature in the bias voltage dependence of the differential conductivity, which can be detected experimentally.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Enkova, Eugenia O., Stepanenko, Vitaly A., Shustin M. S.
Заглавие : Symmetry analysis of radial profiles of magnetic skyrmions
Колич.характеристики :9 с
Место публикации : J. Sib. Fed. Univ. Math. Phys. - 2023. - Vol. 16, Is. 6. - P.811-819. - ISSN 19971397 (ISSN); Журн. СФУ. Матем. и физ. - ISSN 23136022 (eISSN)
Примечания : Cited References: 16. - S.M.S. thanks Maria Potkina as the author of magnetic skyrmionium ansantz, for fruitful discussions and her enormous contribution to this work. The authors thank D. M. Dzebisashvili for useful discussions. The work was carried out within the state assignment of Kirensky Institute of Physics. The work was supported by the Foundation for the Development of Theoretical Physics and Mathematics "BASIS" (project no. 23-1-3-52-1), Krasnoyarsk Mathematical Center of the Ministry of Science and Higher Education of the Russian Federation, Agreement no. 75-02-2023-936
Аннотация: The search for analytical profiles of chiral magnetic structures such as 2D magnetic skyrmions (MS) is important for their theoretical study. Since the Euler–Lagrange (EL) equations for such excita- tions are not solved exactly, the MSs are described using analytical ansatzs. In this work, we validate one of the widely used ansatzs based on a symmetry analysis of the 1D analog of the EL equations, which characterizes the radial profile of the MS. As a development of this approach, a profiles of skyrmion bags are proposed.Поиск аналитических профилей киральных магнитных структур типа 2D магнитных скирмионов (МС) является важным при их теоретическом описании. Поскольку уравнения Эйлера–Лагранжа (ЭЛ) для таких возбуждений не решаются точно, описание МС проводят с помощью аналитических пробных функций — анзацев. В настоящей работе проводится обоснование одного из широко используемых анзацей на основе симметрийного анализа 1D версии уравнений ЭЛ, определяющего радиальный профиль МС. В развитии такого подхода предлагаются профили скирмионных мешков с топологическими зарядами Q ≥ 0.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Krasikov A. A., Knyazev Yu. V., Balaev D. A., Stolyar S. V., Ladygina V. P., Balaev A. D., Iskhakov R. S.
Заглавие : Magnetic interparticle interactions and superparamagnetic blocking of powder systems of biogenic ferrihydrite nanoparticles
Колич.характеристики :11 с
Место публикации : J. Exp. Theor. Phys. - 2023. - Vol. 137, Is. 6. - P.903-913. - ISSN 10637761 (ISSN), DOI 10.1134/S1063776123120075. - ISSN 10906509 (eISSN)
Примечания : Cited References: 58. - This study was supported by the Russian Science Foundation, project no. 22-72-00134
Аннотация: The magnetic-field dependence of the superparamagnetic-blocking temperature TB of systems of antiferromagnetically ordered ferrihydrite nanoparticles has been investigated and analyzed. We studied two powder systems of nanoparticles: particles of “biogenic” ferrihydrite (with an average size of 2.7 nm), released as a result of vital functions of bacteria and coated with a thin organic shell, and particles of biogenic ferrihydrite subjected to low-temperature annealing, which cause an increase in the average particle size (to 3.8 nm) and burning out of the organic shell. The character of the temperature dependences of magnetization, measured after cooling in a weak field, as well as the shape of the obtained dependences TB(H), demonstrate peculiar features, indicating the influence of magnetic interparticle interactions. A detailed analysis of the dependences TB(H) within the random magnetic anisotropy model made it possible to estimate quantitatively the intensity of magnetic particle–particle interactions and determine the magnetic anisotropy constants of individual ferrihydrite particles.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zinenko V. I.
Заглавие : Thermodynamics of spin ice on an antiperovskite lattice in the cluster approximation
Колич.характеристики :5 с
Место публикации : Phys. Solid State. - 2023. - Vol. 65, Is. 7. - P.1203-1207. - ISSN 10637834 (ISSN), DOI 10.21883/PSS.2023.07.56415.63. - ISSN 10906460 (eISSN)
Примечания : Cited References: 9
Аннотация: Low-temperature thermodynamic properties of spin ice have been studied for compounds with the structure of antiperovskite containing rare-earth ions with the general chemical formula ReMeO (where Re - is a rare-earth element, Me - is a divalent metal). The calculations were carried out in the cluster approximation. The cases of undistorted and distorted ORe6 octahedron are discussed. In the case of an undistorted octahedron in the absence of an external magnetic field, the ground state of the system is infinitely degenerate. When an external magnetic field is applied, anomalies in the temperature dependences of heat capacity, entropy and magnetization are detected. In the case of a distorted octahedron and assuming that this distortion leads to the energy efficiency of two of the sixty-four configurations, it is obtained that there is a phase transition in the system of magnetic rare-earth ions.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Patrin G. S., Kobyakov A. V., Yushkov V. I., Anisimov I. O., Zharkov S. M., Semenov S. V., Moiseenko, Evgeniy T.
Заглавие : Influence of a thin V2O3 spacer on interlayer interactions in Fe-Ni/V2O3/FeNi film structures
Колич.характеристики :10 с
Место публикации : Processes. - 2023. - Vol. 11, Is. 7. - Ст.2084. - ISSN 22279717 (eISSN), DOI 10.3390/pr11072084
Примечания : Cited References: 25. - The research was conducted according to the state assignment of the Ministry of Science and Higher Education of the Russian Federation and the Federal State Autonomous Educational Institution of Higher Education Siberian Federal University (No. FSRZ-2023-0008)
Аннотация: In this paper, we explore the suggestions of the results of experimental studies on low-dimensional layered systems in FeNi/V2O3/FeNi film structures. The multifunctional material V2O3 is used as an interlayer between the magnetically active FeNi layers. The films were obtained by ultrahigh vacuum magnetron sputtering on a glass substrate with a base size of 10−10 Torr. It has been found that for V2O3 films, the decrease in the metal–semiconductor transition temperature increases significantly. Magnetic characteristics were studied on the MPMS-XL SQUID magnetometer. The exchange effect occurs both in the region where the oxide has a magnetic order and in the paramagnetic region. The latter is due to the effect of the magnetic panel in the oxide package. The phenomenon of oscillation of the exchange field occurs depending on the phenomenon of intermediate observation observed experimentally.
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12.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Semenov S. V., Ikkert O. P., Balaev D. A., Karnachuk O. V., Knyazev Yu. V.
Заглавие : Forc analysis of interparticle interactions in biomineralized magnetic nanocomposites
Коллективы : Байкальская международная конференция "Магнитные материалы. Новые технологии", "Магнитные материалы. Новые технологии", Байкальская международная конференция, "Magnetic materials. New tecnologies", Baikal International Conference, Иркутский государственный университет
Место публикации : Магнитные материалы. Новые технологии: тез. докл. IX Байкал. междунар. конф. BICMM-2023/ чл. прогр. ком.: S. S. Aplesnin [et al.] ; чл. орг. ком. R. S. Iskhakov [et al.]. - Иркутск, 2023. - P.143. - ISBN 978-5-00133-051-6, DOI 10.26516/978-5-9624-2178-0.2023.1-207
Примечания : Библиогр.: 3
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shustin M. S.
Заглавие : Stable Majorana modes in spin-polarized wire with strong interactions
Место публикации : J. Supercond. Novel Magn. - 2022. - Vol. 35, Is. 8: The Kourovka Winter School of Theoretical Physics. - P.2209-2216. - ISSN 15571939 (ISSN), DOI 10.1007/s10948-022-06238-0
Примечания : Cited References: 42. - The study was funded by the Foundation for the Advancement of Theoretical Physics and Mathematics “BASIS” (Grant No. 20-1-4-25-1); Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science (Project No. 20-42-243001); and Council of the President of the Russian Federation for Support of Young Scientists and Leading Scientific Schools (Grant No. MK-4687.2022.1)
Аннотация: For the 1D Hubbard model with spin-orbit coupling and proximity-induced s-wave superconductivity, the damping rates of quasiparticles are studied in the framework of density-matrix renormalization group (DMRG) approach. It is shown that low-energy excitations belonging to the Hubbard bands are stable against strong electron interaction at the spin-polarized regime. In order to confirm this result analytically, the low-energy model of the strongly interacting spin-polarized nanowire was derived in the second order of perturbation theory. This model generalizes Kitaev chain, taking into account the hoppings and anomalous pairings in the secondary coordination spheres as well as terms describing charge correlations. The amplitudes of the latter ones are small, and the system can be effectively described by quadratic Hamiltonian supporting stable Majorana excitations, which confirms numerical calculations. The topological phase diagram of effective model is studied in the framework of mean-field approximation. The evolution of topological phase boundaries under increasing of charge correlations is studied, and the important role of the joint realization of different types of interactions is noted. The results obtained can be applied when describing the Al-EuS-InAs hybrid system, recently synthesized and studied in searching for Majorana bound states.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Knyazev Yu. V., Balaev D. A., Yaroslavtsev R. N., Krasikov A. A., Velikanov D. A., Mikhlin Y. L., Volochaev M. N., Bayukov O. A., Stolyar S. V., Iskhakov R. S.
Заглавие : Tuning of the interparticle interactions in ultrafine ferrihydrite nanoparticles
Место публикации : Adv. Nano Res. - 2022. - Vol. 12, Is. 6. - P.605-616. - ISSN 2287237X (ISSN), DOI 10.12989/anr.2022.12.6.605
Примечания : Cited References: 73. - This study was supported by the Russian Science Foundation, project no. 21-72-00025 “Tuning the Magnetic Properties of Ultrafine Biocompatible Ferrihydrite Nanoparticles through Interparticle Interactions” (https://rscf.ru/project/21-72-00025/)
Аннотация: We prepared two samples of ultrafine ferrihydrite (FH) nanoparticle ensembles of quite a different origin. First is the biosynthesized sample (as a product of the vital activity of bacteria Klebsiella oxytoca (hereinafter marked as FH-bact) with a natural organic coating and negligible magnetic interparticle interactions. And the second one is the chemically synthesized ferrihydrite (hereinafter FH-chem) without any coating and high level of the interparticle interactions. The interparticle magnetic interactions have been tuned by modifying the nanoparticle surface in both samples. The coating of the FH-bact sample has been partially removed by annealing at 150℃ for 24 h (hereinafter FH-annealed). The FH-chem sample, vice versa, has been coated (1.0 g) with biocompatible polysaccharide (arabinogalactan) in an ultrasonic bath for 10 min (hereinafter FH-coated). The changes in the surface properties of nanoparticles have been controlled by XPS. According to the electron microscopy data, the modification of the nanoparticle surface does not drastically change the particle shape and size. A change in the average nanoparticle size in sample FH-annealed to 3.3 nm relative to the value in the other samples (2.6 nm) has only been observed. The estimated particle coating thickness is about 0.2-0.3 nm for samples FH-bact and FH-coated and 0.1 nm for sample FH-annealed. Mössbauer and magnetization measurements are definitely shown that the drastic change in the blocking temperature is caused by the interparticle interactions. The experimental temperature dependences of the hyperfine field hf(T) for samples FH-bact and FH-coated have not revealed the effect of interparticle interactions. Otherwise, the interparticle interaction energy Eint estimated from the hf(T) for samples FH-chem and FH-annealed has been found to be 121kB and 259kB, respectively.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Stolyar S. V., Knyazev Yu. V., Yaroslavtsev R. N., Pankrats A. I., Vorotynov A. M., Krasikov A. A., Velikanov D. A., Bayukov O. A., Ladygina V. P., Iskhakov R. S.
Заглавие : Role of the surface effects and interparticle magnetic interactions in the temperature evolution of magnetic resonance spectra of ferrihydrite nanoparticle ensembles
Место публикации : Results Phys. - 2022. - Vol. 35. - Ст.105340. - ISSN 22113797 (ISSN), DOI 10.1016/j.rinp.2022.105340
Примечания : Cited References: 119. - Authors thank to A.D. Balaev, S.V. Komogortsev for fruitful discussions and M.N. Volochaev for TEM studies. The TEM study and measurements of X-band FMR spectra were carried out on the equipment of the Krasnoyarsk Territorial Center for Collective Use, Krasnoyarsk Scientific Center, Siberian Branch, Russian Academy of Sciences. This study was supported by the Russian Science Foundation, project no. 21-72-00025 (https://rscf.ru/project/21-72-00025/) "Tuning the Magnetic Properties of Ultrafine Biocompatible Ferrihydrite Nanoparticles through Interparticle Interactions"
Аннотация: Ferrihydrite is characterized by the antiferromagnetic ordering and, in ferrihydrite nanoparticles, as in nanoparticles of any antiferromagnetic material, an uncompensated magnetic moment is formed. We report on the investigations of ferrihydrite powder systems with an average particle size of ∼ 2.5 nm obtained (i) as a product of the vital activity of bacteria (sample FH-bact) and (ii) by a chemical method (sample FH-chem). In the first approximation, these samples can be considered to be identical. However, in sample FH-chem, particles contact directly, while in sample FH-bact, they have organic shells; therefore, the interparticle magnetic interactions in these samples have different degrees. The main goal of this work has been to establish the effects of the interparticle magnetic interactions and individual characteristics of ferrihydrite nanoparticles on ferromagnetic resonance (FMR) spectra. The FMR spectra have been measured at different (9.4–75 GHz) frequencies in a wide temperature range. It has been found that, at low temperatures, the field-frequency dependence ν(HR) of the investigated systems has a gap ν/γ = HR + HA, where HR is the resonance field and HA is the induced anisotropy, which decreases with increasing temperature. To estimate a degree of the effect of interparticle interactions on the results obtained and to correctly determine the temperature range of the superparamagnetic (or blocked) state, the static magnetic measurement and Mössbauer spectroscopy data have been obtained and analyzed. It has been shown that the most striking feature of the FMR spectra - a gap in the field-frequency dependences - is a manifestation of individual characteristics of ferrihydrite nanoparticles. The induced anisotropy is caused by freezing of a subsystem of surface spins and its coupling with the particle core, which is observed in both samples at a temperature of ∼80 K. The temperature range (below 80 K) in which the gap exists corresponds to the blocked state in the FMR technique. In sample FH-bact, the ratio between the FMR parameters HA and linewidth ΔH obeys the standard expression HA ∼ (ΔH)3. In sample FH-chem, however, the interparticle magnetic interactions dramatically affect the behavior of parameters of the FMR spectra, which change nonmonotonically upon temperature variation. This fact is attributed to the collective freezing of the magnetic moments of particles under the conditions of sufficiently strong interactions, which follows from the temperature dependence of the particle magnetic moment relaxation time determined from the Mössbauer spectroscopy and static magnetometry data obtained in weak magnetic fields.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Knyazev Yu. V., Balaev D. A., Stolyar S. V., Krasikov A. A., Bayukov O. A., Volochaev M. N., Yaroslavtsev R. N., Ladygina V. P., Velikanov D. A., Iskhakov R. S.
Заглавие : Interparticle magnetic interactions in synthetic ferrihydrite: Mossbauer spectroscopy and magnetometry study of the dynamic and static manifestations
Место публикации : J. Alloys Compd. - 2022. - Vol. 889. - Ст.161623. - ISSN 09258388 (ISSN), DOI 10.1016/j.jallcom.2021.161623
Примечания : Cited References: 84. - This study was supported by the Russian Foundation for Basic Research, the Government of the Krasnoyarsk Territory, and the Krasnoyarsk Territorial Foundation for Support of Scientific and R&D Activities, project no. 19–42–240012 R-A “Magnetic Resonance in Ferrihydrite Nanoparticles: Effects Related to the Core-Shell Structure”
Аннотация: Samples of synthetic ferrihydrite with an average nanoparticle size of 2.7 nm have been examined by magnetometry and Mossbauer spectroscopy. Ferrihydrite is characterized by the antiferromagnetic interactions between the magnetic moments of iron atoms. In ferrihydrite nanoparticles, as in any other antiferromagnetic ones, structural defects induce the formation of an uncompensated magnetic moment, which determines the magnetic properties typical of single-domain ferro- and ferrimagnetic particles. The manifestation of the magnetic interactions between ferrihydrite nanoparticles in the magnetic properties of the material and in the temperature evolution of Mossbauer spectra has been in focus. The results obtained on synthetic ferrihydrite have been compared with the data for the biogenic ferrihydrite sample with a similar average size of particles surrounded by a polysaccharide shell, which weakens and screens the interparticle magnetic interactions. A clear manifestation of the effect of the interparticle magnetic interactions on the transition to the blocked state is the presence of a significant contribution of the relaxation component in the Mossbauer spectra at temperatures of the transition from the superparamagnetic to blocked state. The temperature dependence of the particle relaxation time obtained from the Mossbauer spectra points out the collective effect of freezing of the magnetic moments of particles due to the magnetic interactions between them.
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17.

Вид документа : Статья из журнала
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Автор(ы) : Cazacu, Nicoleta, Chilom, Claudia G., Iftimie, Sorina, Balasoiu, Maria, Ladygina, Valentina P., Stolyar S. V., Orelovich, Oleg L., Kovalev, Yuriy S., Rogachev, Andrey V.
Заглавие : Biogenic ferrihydrite nanoparticles produced by Klebsiella oxytoca: Characterization, physicochemical properties and bovine serum albumin interactions
Место публикации : Nanomaterials. - 2022. - Vol. 12, Is. 2. - Ст.249. - ISSN 2079-4991(eISSN), DOI 10.3390/nano12020249
Примечания : Cited References: 59. - This research was funded by JINR Themes 02-1-1107-2011/2021, 04-5-1131-2017/2021 and 04-4-1133-2018/2023 and with the financial support of the RO-JINR Projects Nos. 366/11.05.2021 (items 7, 86, 97) and 365/11.05.2021 (items 8, 87 and 98). This work also benefited from the use of the SasView application, originally developed under NSF Award DMR-0520547. SasView also contains the code developed with funding from the EU Horizon 2020 program under the SINE2020 project Grant No 654000. The APC was funded by JINR Theme 02-1-1107-2011/2021, Project No. 366/11.05.2021, item 7. This study used the infrastructure of the Applied Genetics Resource Facility of MIPT (Suport Grant 075-15-2021-684)
Предметные рубрики: MAGNETIC-PROPERTIES
REDUCTION
MOSSBAUER
FERRITIN
DOCKING
BINDING
Аннотация: The synthesis of nanoparticles inside microorganisms is an economical alternative to chemical and physical methods of nanoparticle synthesis. In this study, ferrihydrite nanoparticles synthesized by Klebsiella oxytoca bacterium in special conditions were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDS), small-angle X-ray (SAXS), UV-Vis spectroscopy, fluorescence, fluorescence resonance energy transfer (FRET), and molecular docking. The morphology and the structure of the particles were characterized by means of SEM and SAXS. The elemental content was determined by means of the EDS method. The absorption properties of the ferrihydrite nanoparticles were investigated by UV-Vis spectroscopy. The binding mechanism of the biogenic ferrihydrite nanoparticles to Bovine Serum Albumin (BSA) protein, studied by fluorescence, showed a static and weak process, combined with FRET. Protein denaturation by temperature and urea in the presence of the ferrihydrite nanoparticles demonstrated their influence on the unfolding process. The AutoDock Vina and UCSF Chimera programs were used to predict the optimal binding site of the ferrihydrite to BSA and to find the location of the hydrophobic cavities in the sub-domain IIA of the BSA structure.
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18.

Вид документа : Статья из журнала
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Автор(ы) : Knyazev Yu. V., Ikkert O. P., Semenov S. V., Volochaev M. N., Molokeev M. S., Platunov M. S., Khramov E. V., Dubrovskiy A. A., Shestakov N. P., Smorodina E. D., Karnachuk O. V., Balaev D. A.
Заглавие : Superparamagnetic blocking and magnetic interactions in nanoferrihydrite adsorbed on biomineralized nanorod-shaped F3S4 crystallites
Место публикации : J. Alloys Compd. - 2022. - Vol. 923. - Ст.166346. - ISSN 09258388 (ISSN), DOI 10.1016/j.jallcom.2022.166346
Примечания : Cited References: 109. - This study was supported by the Russian Science Foundation, project no. 22-24-00601 (https://rscf.ru/project/22–24–00601/)The electron microscopy and Mössbauer spectroscopy studies were carried out on the equipment of the Krasnoyarsk Territorial Center for Collective Use, Krasnoyarsk Scientific Center, Siberian Branch of the Russian Academy of Sciences. We thank Dr. Ivan Nemtsev for the SEM images. The contribution of M. P. (development of methodology of sample preparation for EXAFS measurements) was partially supported by the Russian Ministry of Science and Higher Education via the budget project of SRF SKIF, Boreskov Institute of Catalysis
Аннотация: A composite based on nanorod-shaped greigite (Fe3S4) crystallites with adsorbed ferrihydrite (Fe2O3 ‧ nH2O) nanoparticles has been synthesized. The synthesis has been performed by biomineralization of the bacterial wall of a sulfate-reducing Desulfovibrio sp. A2 bacteria. The phase composition of the synthesized composite has been investigated by X-ray powder and electron diffraction, as well as Fourier-transform infrared, extended X-ray absorption fine structure, and Mössbauer spectroscopy. The magnetic measurement data have shown that the sample under study contains two magnetic phases: multidomain nanorod-shaped greigite and ultrasmall ferrihydrite nanoparticles. The constant atomic fraction of the greigite crystalline phase in the range of 4–300 K (~20%) revealed by Mössbauer spectroscopy is indicative of a blocked magnetic moment of nanorod-shaped Fe3S4. It is shown that nanorod-shaped Fe3S4 crystallites are strongly magnetically bound with adsorbed Fe2O3 ‧ nH2O (Eint ~ 1200kB) nanoparticles. This significantly slows down the superparamagnetic relaxation of the magnetic moments of ferrihydrite nanoparticles. Therefore, the blocking temperature noticeably increases and attains, according to the Mössbauer spectroscopy data, a value of TB = 140 K (the magnetic measurements yield TB = 72 K). The processes of superparamagnetic blocking of the magnetic moments of ferrihydrite nanoparticles manifest themselves in the evolution of the magnetic properties of the investigated sample (a significant increase in the coercivity and remanent magnetization). In support of the Mössbauer spectroscopy data, a sufficiently high superparamagnetic blocking temperature has been established, which discloses the effect of magnetizing of ferrihydrite nanoparticles by coarser greigite formations, analogously to the effect of interparticle magnetic interactions.
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19.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Aksenov S. V., Fedoseev A. D., Shustin M. S., Zlotnikov A. O.
Заглавие : Effective interactions in higher-order topological superconductors with strong electron correlations
Коллективы : Российская академия наук, Физико-технический институт им. Е.К. Завойского ФИЦ Казанского научного центра РАН, Казанский (Приволжский) федеральный университет, Euro-Asian Symposium "Trends in MAGnetism", "Trends in MAGnetism", Euro-Asian Symposium
Место публикации : VIII Euro-Asian symposium "Trends in magnetism" (EASTMAG-2022): Book of abstracts/ program com. S. G. Ovchinnikov [et al.]. - 2022. - Vol. 2, Sect. I: Magnetism and superconductivity. - Ст.I.P7. - P.164-165. - ISBN 978-5-94469-051-7
Примечания : Cited References: 7. - The study was supported by Russian Science Foundation, project 22-22-20076
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20.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Balaev D. A., Stolyar S. V., Krasikov A. A., Bayukov O. A., Yaroslavtsev R. N., Velikanov D. A., Iskhakov R. S., Knyazev Yu. V.
Заглавие : Effect of the interparticle interactions on superparamagnetic relaxation
Коллективы : Российская академия наук, Физико-технический институт им. Е.К. Завойского ФИЦ Казанского научного центра РАН, Казанский (Приволжский) федеральный университет, Euro-Asian Symposium "Trends in MAGnetism", "Trends in MAGnetism", Euro-Asian Symposium
Место публикации : VIII Euro-Asian symposium "Trends in magnetism" (EASTMAG-2022): Book of abstracts/ program com. S. G. Ovchinnikov [et al.]. - 2022. - Vol. 1, Sect.: Magnetotransport, magnetooptics and magnetophotonics. - Ст.D.O11. - P.437-438. - ISBN 978-5-94469-051-7
Примечания : Cited References: 3. - This study was supported by the Russian Science Foundation, Project No. 21-72-00025 (https://rscf.ru/project/21-72-00025/)
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