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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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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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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Yurkin G. Yu., Patrin G. S., Velikanov D. A., Beletsky V. V.
Заглавие : Transport properties of FeSi with cobalt impurities
Место публикации : TRENDS IN MAGNETISM. - 2011. - Vol. 168-169. - С. 493-496. - ISSN 10120394 (ISSN); 9783037850213 (ISBN), DOI 10.4028/www.scientific.net/SSP.168-169.493
Ключевые слова (''Своб.индексиров.''): iron monosilicide--kondo effect--magnetization--resistivity--spindependent scattering--superparamagnetic cluster--cobalt--crystals--electric resistance--electron energy loss spectroscopy--kondo effect--magnetic field effects--magnetic properties--magnetization--magnetoresistance--scattering--superparamagnetism--transport properties--cobalt--electric conductivity--electron scattering--impurities--kondo effect--magnetism--magnetization--experimental investigations--kondo models--magnetoresistance properties--resistivity--si crystals--spin dependent scattering--superparamagnetic clusters--crystal impurities--crystal impurities
Аннотация: The results of experimental investigations of Fe1-xCo xSi crystals in the impurity limit are presented in this article. We made an attempt to study changes of magnetic properties and conductivity in mixed Fe1-xCoxSi crystals in the impurity limit. Magnetoresistance properties are well described in the framework of Kondo model. The presence of Co-subsystem leads to the occurrence of spin-dependent channel in electron scattering conduction.
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Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Li O. A., Edelman I. S., Chun-Rong Lin, Hung-Yi Chen, Kai-Wun Wu, Ovchinnikov S. G.
Заглавие : The unusual size dependence of magnetic properties of nickel zinc ferrite nanoparticles synthesized by combustion method
Коллективы : Euro-Asian Symposium "Trends in MAGnetism", "Trends in MAGnetism", Euro-Asian Symposium, Институт физики им. Л.В. Киренского Сибирского отделения РАН
Место публикации : VI Euro-Asian Symposium "Trends in MAGnetism" (EASTMAG-2016): abstracts/ ed.: O. A. Maksimova, R. D. Ivantsov. - Krasnoyarsk: KIP RAS SB, 2016. - Ст.P9.5. - P.391. - ISBN 978-5-904603-06-9 (Шифр -478014040)
Ключевые слова (''Своб.индексиров.''): nickel zinc ferrite--ferrite nanoparticles --superparamagnetism
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Petrakovskaya E. A., Isakova V. G., Bayukov O. A., Velikanov D. A.
Заглавие : Superparamagnetism of magnetite particles in C-60 fullerite powder
Разночтения заглавия :авие SCOPUS: Superparamagnetism of magnetite particles in C60 fullerite powder
Место публикации : Tech. Phys.: AMER INST PHYSICS, 2005. - Vol. 50, Is. 6. - P790-793. - ISSN 1063-7842, DOI 10.1134/1.1947359
Примечания : Cited References: 9
Предметные рубрики: RESONANCE
Аннотация: A new magnetic material, C-60 fullerite powder doped by magnetite (Fe3O4) nanoparticles, is obtained by heating a mixture of fullerite and iron(III) acetylacetonate. It is shown that the material offers superparamagnetic properties. Surface bonding between the nanoparticles and the fullerite is established. (c) 2005 Pleiades Publishing, Inc.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Khrustalev B. P., Balaev A. D., Sosnin V. M.
Заглавие : Superparamagnetism in Fe-SiO nanocluster films
Место публикации : Fiz. Tverd. Tela: MEZHDUNARODNAYA KNIGA, 1995. - Vol. 37, Is. 6. - P.1676-1686. - ISSN 0367-3294
Примечания : Cited References: 30
Предметные рубрики: ELECTRICAL-PROPERTIES
TEMPERATURE
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Edelman I. S., Ivantsov R., Vasiliev A., Stepanov S., Kornilova E., Zarubina T.
Заглавие : Superparamagnetic and ferrimagnetic nanoparticles in glass matrix
Место публикации : Physica B. - 2001. - Vol. 301, Is. 3-4. - P.203-211. - ISSN 0921-4526, DOI 10.1016/S0921-4526(01)00274-5
Примечания : Cited References: 9
Предметные рубрики: MAGNETIC-PROPERTIES
PARTICLES
FILMS
Ключевые слова (''Своб.индексиров.''): magnetic nanoparticles--faraday rotation--faraday rotation--magnetic nanoparticles--crystal structure--faraday effect--ferrimagnetic materials--glass--particle size analysis--superparamagnetism--x ray diffraction analysis--amorphous glass matrices--faraday rotations--nanostructured materials
Аннотация: Faraday rotation (FR) spectral, field, and temperature dependencies in oxide glasses with small additions of paramagnetic elements are investigated. Formation of ferrite nanoparticles in amorphous glass matrices is revealed by X-ray diffraction. Particles have crystal structure similar to spinel structure, their dimensions are about 10-24 nm. The FR field dependencies are typical for ferrimagnetic or superparamagnetic substances depending on particle size. Strong FR increase at the samples cooling (more than twice for some samples) in the temperature interval 105-273 K is observed. (C) 2001 Elsevier Science B.V. All rights reserved.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Vazhenina I. G., Stolyar S. V., Tyumentsev A. V., Volochaev M. N., Iskhakov R. S., Komogortsev S. V., Pyankov V. F., Nikolaeva E. D.
Заглавие : Study of magnetic iron oxide nanoparticles coated with silicon oxide by ferromagnetic method
Колич.характеристики :5 с
Коллективы : Nanophysics and Nanoelectronics, International Symposium
Место публикации : Phys. Solid State. - 2023. - Vol. 65, Is. 6. - P.884-888. - ISSN 10637834 (ISSN), DOI 10.21883/PSS.2023.06.56095.01H. - ISSN 10906460 (eISSN)
Примечания : Cited References: 20. - The study was supported by grant No. 22-14-20020 provided by the Russian Science Foundation, Krasnoyarsk Regional Science Foundation
Аннотация: agnetic nanoparticles of magnetite with a size of ~8 nm synthesized with a different type of coating were studied by ferromagnetic resonance in the temperature range from 7 to 300 K. The features of the experimental temperature dependences of the parameters of the ferromagnetic resonance curve (the magnitude of the resonant field, line width and intensity) and their approximation allowed us to estimate the values of characteristic temperatures. Firstly, the value of the Vervey temperature and the dependence of its value on the type of coating were determined. Secondly, the temperature of transition of nanoparticles to the superparamagnetic state (blocking temperature) and the temperature range within which the magnetic structure of the outer shell of the magnetic nanoparticle is in the spin glass state are established.
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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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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Knyazev Yu. V., Balaev D. A., Kirillov V. L., Bayukov O. A., Mart'yanov O. N.
Заглавие : Mossbauer spectroscopy study of the superparamagnetism of ultrasmall ε-Fe2O3 nanoparticles
Коллективы : Russian Science Foundation [17-12-01111]
Место публикации : JETP Letters. - 2018. - Vol. 108, Is. 8. - P.527-531. - ISSN 0021-3640, DOI 10.1134/S0021364018200092. - ISSN 1090-6487(eISSN)
Примечания : Cited References: 22. - This work was supported by the Russian Science Foundation (project no. 17-12-01111).
Предметные рубрики: High-temperature
Particles
ε-Fe2O3
Phase
Model
Аннотация: The superparamagnetism of an ensemble of ϵ-Fe2O3 nanoparticles with a mean size of 3.9 nm dispersed in a xerogel SiO2 matrix is studied by the Mössbauer spectroscopy method. It is shown that most nanoparticles at room temperature are in the superparamagnetic (unblocked) state. As the temperature decreases, the progressive blocking of the magnetic moments of the particles occurs, which is manifested in the Mössbauer spectra as the transformation of the quadrupole doublet into a Zeeman sextet. The analysis of the relative intensity of the superparamagnetic (quadrupole doublet) and magnetically split (sextets) spectral components in the range of 4–300 K provides the particle size distribution, which is in agreement with the transmission electron microscopy data. The values of the effective magnetic anisotropy constants (Keff) are determined, and the contribution of surface anisotropy (KS) is estimated for particles of various sizes. It is shown that the quantity Keff is inversely proportional to the particle size, which indicates the significant contribution of the surface to the magnetic state of the ϵ-Fe2O3 nanoparticles with the size of several nanometers.
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