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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Safronov A. P., Beketov I. V., Komogortsev S. V., Kurlyandskaya G. V., Medvedev A. I., Leiman D. V., Larranaga A., Bhagat S. M.
Заглавие : Spherical magnetic nanoparticles fabricated by laser target evaporation
Место публикации : AIP Adv.: American Institute of Physics, 2013. - Vol. 3, Is. 5. - Ст.052135. - P. - ISSN 2158-3226, DOI 10.1063/1.4808368
Примечания : Cited References: 47. - This work was supported by the RFBR 10-02-96015 and 12-02-31385 projects, UrFU 215, Spanish MEC MAT2011-27573-C04 grants, Universidad del Pais Vasco UPV/EHU under UFI11/53 action and Physics Department of the University of Maryland visiting grant. Selected measurements were performed at SGIker service of UPV-EHU. We thank O.M. Samatov, Dr. A.M. Murzakayev, Dr. I. Orue, and A.A. Svalova for special support.
Предметные рубрики: IRON-OXIDE NANOPOWDERS
CO2-LASER EVAPORATION
FE3O4 NANOPARTICLES
FINITE-SIZE
TEMPERATURE
FERROMAGNETS
FERROFLUIDS
DEPENDENCE
EXPLOSION
PARTICLES
Аннотация: Magnetic nanoparticles of iron oxide (MNPs) were prepared by the laser target evaporation technique (LTE). The main focus was on the fabrication of de-aggregated spherical maghemite MNPs with a narrow size distribution and enhanced effective magnetization. X-ray diffraction, transmission electron microscopy, magnetization and microwave absorption measurements were comparatively analyzed. The shape of the MNPs (mean diameter of 9 nm) was very close to being spherical. The lattice constant of the crystalline phase was substantially smaller than that of stoichiometric magnetite but larger than the lattice constant of maghemite. High value of M-s up to 300 K was established. The 300 K ferromagnetic resonance signal is a single line located at a field expected from spherical magnetic particles with negligible magnetic anisotropy. The maximum obtained concentration of water based ferrofluid was as high as 10g/l of magnetic material. In order to understand the temperature and field dependence of MNPs magnetization, we invoke the core-shell model. The nanoparticles is said to have a ferrimagnetic core (roughly 70 percent of the caliper size) while the shell consists of surface layers in which the spins are frozen having no long range magnetic order. The core-shell interactions were estimated in frame of random anisotropy model. The obtained assembly of de-aggregated nanoparticles is an example of magnetic nanofluid stable under ambient conditions even without an electrostatic stabilizer. (C) 2013 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Komogortsev S. V., Iskhakov R. S., Zimin A. A., Filatov E. Y., Korenev S. V., Shubin Y. V., Chizhik N. A., Yurkin G.Yu., Eremin E. V.
Заглавие : Magnetic anisotropy and order parameter in nanostructured CoPt particles
Коллективы : RFBR [11-03-00168-a, 12-02-00943-a]; Interdisciplinary integration of fundamental research of SB RAS [64]; Russian Federation [MK-1934.2013.3]
Место публикации : Appl. Phys. Lett.: American Institute of Physics, 2013. - Vol. 103, Is. 15. - Ст.152404. - P. - ISSN 0003-6951, DOI 10.1063/1.4824973
Примечания : Cited References: 36. - The authors are grateful to Dr. A. V. Zadesenets for synthesis of CoPt complex precursor and Dr. A. S. Bogomyakov for assistance in magnetic measurements. The work was supported by RFBR (Grant Nos. 11-03-00168-a and 12-02-00943-a), Interdisciplinary integration of fundamental research of SB RAS (2012-2014) project No. 64, and grant of the President of the Russian Federation (No. MK-1934.2013.3).
Предметные рубрики: FEPT THIN-FILMS
REMANENT MAGNETIZATION
UNIAXIAL ANISOTROPIES
FINE PARTICLES
NANOPARTICLES
FERROMAGNETS
PHASE
Аннотация: The correlation of magnetic anisotropy energy with order parameter in the crystallites of CoPt nanostructured particles prepared by thermal decomposition and further annealing has been studied by investigation of the approach magnetization to saturation curves and x-ray powder diffraction pattern profiles. It is shown that magnetic anisotropy energy value in partially ordered CoPt crystallite could be described as an intermediate case between two extremes, corresponding to either single or several c-domains of L1(0) phase in crystallite. (C) 2013 AIP Publishing LLC.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Denisova E. A., Kuzovnikova L. A., Iskhakov R. S., Bukaemskiy A. A., Eremin E. V., Nemtsev I. V.
Заглавие : Effect of ball milling and dynamic compaction on magnetic properties of Al2O3/Co(P) composite particles
Коллективы : Russian Foundation of Basic Research [13-03-00476-a]
Место публикации : J. Appl. Phys.: American Institute of Physics, 2014. - Vol. 115, Is. 17. - Ст.17B530. - ISSN 0021-8979, DOI 10.1063/1.4869158. - ISSN 1089-7550
Примечания : Cited References: 18. - This work was partially supported by Russian Foundation of Basic Research 13-03-00476-a.
Предметные рубрики: MECHANOCHEMICAL SYNTHESIS
MECHANICAL-PROPERTIES
NANOCOMPOSITE POWDER
ALLOYS
NANOCRYSTALLINE
MICROSTRUCTURE
FERROMAGNETS
Аннотация: The evolution of the magnetic properties of composite Al2O3/Co(P) particles during ball milling and dynamic compaction is investigated. To prepare starting composite particles, the Al2O3 granules were coated with a Co95P5 shell by electroless plating. The magnetic and structural properties of the composite particles are characterized by scanning electron microscopy, X-ray diffraction, and the use of the Physical Property Measurement System. The use of composite core-shell particles as starting powder for mechanoactivation allows to decrease treatment duration to 1 h and to produce a more homogeneous bulk sample than in the case of the mixture of Co and Al2O3 powders. The magnetic properties of the milled composite particles are correlated with changes in the microstructure. Reduction in grain size of Co during milling leads to an increase of the volume fraction of superparamagnetic particles and to a decrease of the saturation magnetization. The local magnetic anisotropy field depends on the amount of hcp-Co phase in sample. The anisotropy field value decreases from 8.4 kOe to 3.8 kOe with an increase in milling duration up to 75 min. The regimes of dynamic compaction were selected so that the magnetic characteristics-saturation magnetization and coercive field-remained unchanged. (C) 2014 AIP Publishing LLC.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Киренский, Леонид Васильевич, Савченко, Михаил Кириллович, Дегтярев И. Ф.
Заглавие : О процессах намагничивания ферромагнетиков
Место публикации : Журн. эксперим. и теор. физ. - 1959. - Т. 37, вып. 3. - С. 616-619
Примечания : Библиогр.: 7 назв. - Phys. Abstr. - 1960. - Vol. 63, 10145
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Iskhakov R. S., Komogortsev S. V., Balaev A. D., Gavriliuk A. A.
Заглавие : The manifestations of the two-dimensional magnetic correlations in the nanocrystalline ribbons Fe64CO21B15
Место публикации : J. Magn. Magn. Mater.: Elsevier Science, 2015. - Vol. 374. - P.423-426. - ISSN 0304-8853, DOI 10.1016/j.jmmm.2014.08.078. - ISSN 1873-4766
Примечания : Cited References: 42
Предметные рубрики: GRAIN-SIZE DEPENDENCE
RANDOM ANISOTROPY
AMORPHOUS-ALLOYS
COERCIVE FORCE
FERROMAGNETS
FILMS
SATURATION
Fe
MICROSTRUCTURE
EVOLUTION
Ключевые слова (''Своб.индексиров.''): magnetic correlations--nanoclystalline alloys--random magnetic anisotropy--coercivity
Аннотация: We report and discuss the grain size dependence of the coercivity and approach magnetization to saturation in the FeCoB ribbons. Instead of expected three-dimensional magnetic correlations for 20 mu m thick ribbon with grain size about 10 nm, the observed behavior could be attributed to the two-dimensional stochastic magnetic domains and two dimensional magnetization ripple. (C) 2014 Elsevier B.V. All rights reserved.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kim P. D., Orlov V. A., Prokopenko V. S., Zamai S. S., Prints, V. Ya, Rudenko R. Y., Rudenko T. V.
Заглавие : On the low-frequency resonance of magnetic vortices in micro- and nanodots
Коллективы : Siberian Branch of the Russian Academy of Sciences [26]
Место публикации : Phys. Solid State: MAIK Nauka-Interperiodica / Springer, 2015. - Vol. 57, Is. 1. - P.30-37. - ISSN 1063, DOI 10.1134/S1063783415010151. - ISSN 10906460(eISSN)
Примечания : Cited References:57. - This study was supported by the Siberian Branch of the Russian Academyof Sciences within the framework of the Interdisciplinary IntegrationProject No. 26 "Ferromagnetic Film Nanodots: Physics of Phenomena andApplications" (2012-2014).
Предметные рубрики: EASY-PLANE FERROMAGNETS
VORTEX CORE
MAGNON MODES
DYNAMICS
FIELD
Аннотация: The resonance motion of the magnetization of thin cylindrical and parallelepiped micro- and nanodots has been studied theoretically and experimentally. Analytical expressions for the external-field dependence of the resonance frequency of the vortex-structure oscillations have been derived taking into account the inertial and damping coefficients. The external-field dependence of the damping parameter has been found theoretically. The influence of the effective mass of a magnetic vortex on its low-frequency dynamics has been discussed.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Komogortsev S. V., Iskhakov R. S., Zimin A. A., Filatov E. Y., Korenev S. V., Shubin Yu. V., Chizhik N. A., Yurkin G. Yu., Eremin E. V.
Заглавие : The exchange interaction effects on magnetic properties of the nanostructured CoPt particles
Место публикации : J. Magn. Magn. Mater.: Elsevier, 2016. - Vol. 401. - P.236-241. - ISSN 0304-8853, DOI 10.1016/j.jmmm.2015.10.041
Примечания : Cited References: 55. - The work has been partially supported by RFBR Grants 15-08-06673, 14-03-00411, 14-03-00129, 15-42-0417115 and it is partly performed in Siberian Federal University within the state contract of the Russian Federation Ministry of Education and Science for 2014-2016 (project number 1792)
Предметные рубрики: CLUSTER BEAM DEPOSITION
BULK MAGNETS
NANOCRYSTALLINE FERROMAGNETS
REMANENCE ENHANCEMENT
THIN-FILMS
COERCIVITY
MICROSTRUCTURE
NANOPARTICLES
IRON
SYSTEM
Аннотация: Various manifestations of the exchange interaction effects in magnetization curves of the CoPt nanostructured particles are demonstrated and discussed. The inter-grain exchange constant A in the sponge-like agglomerates of crystallites is estimated as A=(7±1) pJ/m from the approach magnetization to saturation curves that is in good agreement with A=(6.6±0.5) pJ/m obtained from Bloch T 3/2 law. The fractal dimensionality of the exchange coupled crystallite system in the porous media of the disordered CoPt alloy d=(2.60±0.18) was estimated from the approach magnetization to saturation curve. Coercive force decreases with temperature as Hc~T 3/2 which is assumed to be a consequence of the magnetic anisotropy energy reduction due to the thermal spin wave excitations in the investigated CoPt particles. © 2015 Elsevier B.V. All rightsreserved.Демонстрируются и обсуждаются различные проявления эффектов обменного взаимодействия в кривых намагниченности наноструктуированных частиц CoPt. Межзеренная обменная константа А в агломератах губчатой структуры кристаллитов оценивается как /A/=(7±1) pJ/m из кривых приближения намагниченности к насыщению, это значение находится в хорошем согласии с /A/=(6.6±0.5) pJ/m, полученным из закона /T/. /2 Блоха. Размерность фрактала обменно-соединенных кристаллических систем в пористой среды неупорядоченного сплава CoPt /d/=(2.60±0.18) оценивалась из кривых приближения намагниченности к насыщению. Коэрцитивная сила уменьшается с температурой по закону /H_c /~/T/. /2 , который, как предполагается, есть следствие уменьшения энергии магнитной анизотропии из-за теплового возбуждения спиновых волн в изучаемых частицах CoPt.
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Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Kimel A.
Заглавие : Different physical mechanism of the UFM in ferromagnets with itinerant and localized electrons
Коллективы : Ultrafast Magnetism Conference
Место публикации : Ultrafast Magnetism Conference (UMC2015). - 2015
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shaykhutdinov K. A., Popkov S. I., Semenov S. V., Balaev D. A., Dubrovskiy A. A., Sablina K. A., Sapronova N. V., Volkov N. V.
Заглавие : Low-temperature resistance and magnetoresistance hysteresis in polycrystalline (La0.5Eu0.5)(0.7)Pb0.3MnO3
Разночтения заглавия :авие SCOPUS: Low-temperature resistance and magnetoresistance hysteresis in polycrystalline (La0.5Eu0.5)0.7Pb 0.3MnO3
Место публикации : J. Appl. Phys.: AMER INST PHYSICS, 2011. - Vol. 109, Is. 5. - Ст.53711. - ISSN 0021-8979, DOI 10.1063/1.3559303
Примечания : Cited References: 20. - This study was partially supported by the Russian Foundation for Basic Research, Project No. 08-02-00259a and the Lavrentyev Competition of the Young Scientists' Projects of the Siberian Branch of the Russian Academy of Sciences, Project No. 12.
Предметные рубрики: RESISTIVITY MINIMUM
MANGANITES
FILMS
Ключевые слова (''Своб.индексиров.''): antiferromagnets--electrical resistances--ferromagnets--field dependence--inter-grain--lanthanum manganites--low temperatures--low-temperature resistance--polycrystalline--temperature dependence--tunnel contacts--antiferromagnetic materials--europium--ferromagnetic materials--ferromagnetism--hysteresis--lead--magnetic field effects--magnetoelectronics--magnetoresistance--magnets--manganese oxide--paramagnetism--superconducting materials--electric resistance
Аннотация: The behavior of temperature dependences of electrical resistance and magnetoresistance of polycrystalline substituted lanthanum manganite (La0.5Eu0.5)(0.7)Pb0.3MnO3 at low temperatures was thoroughly studied. A broad hysteresis was found in the field dependences of electrical resistance in the low-temperature region. Above 40 K, no hysteresis feature was observed. The temperature T = 40 K corresponds to the temperature of minimum electrical resistance and the temperature T-N to the antiferromagnet-paramagnet phase transition of the material of the intergrain boundaries. In this work we propose a model which explains the observed features of the rho(T) and rho(H) curves at temperatures below T-N by the formation of a network of ferromagnet-antiferromagnet-ferromagnet tunnel contacts. (C) 2011 American Institute of Physics. [doi:10.1063/1.3559303]
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gorev M., Bogdanov E. V., Flerov I. N., Laptash N. M.
Заглавие : Thermal expansion, phase diagrams and barocaloric effects in (NH4)(2)NbOF5
Коллективы :
Разночтения заглавия :авие SCOPUS: Thermal expansion, phase diagrams and barocaloric effects in (NH 4)2NbOF5
Место публикации : J. Phys.: Condens. Matter: IOP PUBLISHING LTD, 2010. - Vol. 22, Is. 18. - Ст.185901. - ISSN 0953-8984, DOI 10.1088/0953-8984/22/18/185901
Примечания : Cited References: 17. - This work was supported in part by the Krasnoyarsk Regional Foundation for Support of Scientific and Scientific-Technological Investigations and RFBR in the framework of project 'Siberia' (Grant No. 09-02-98001), and the Council on Grants from the President of the Russian Federation for Support of Leading Scientific Schools (project No. Nsh-1011.2008.2).
Предметные рубрики: CRYSTAL-STRUCTURE
SOLID-STATE
OXYFLUORIDE
TRANSITION
ANION
Ключевые слова (''Своб.индексиров.''): antiferromagnets--ferromagnets--heat capacities--high stress--intermediate phase--pippard relations--structural phase transition--transition temperature--uniaxial pressures--financial data processing--phase diagrams--phase transitions--thermal stress--tools--thermal expansion
Аннотация: The thermal expansion along the a, b and c axes of a (NH4)(2)NbOF5 crystal was measured from 120 to 300 K. Anomalies of alpha(T) associated with previously reported phase transitions Cmc2(1) - C-2 - I a were observed along all directions at T-1 = 259.3 K and T-2 = 220.5 K. The analysis of thermal expansion and heat capacity in the frame of the Pippard relations has permitted us to determine the uniaxial pressure derivatives of the transition temperatures dT/d sigma(i). The T-sigma(i) phase diagrams have shown a tendency for the intermediate phase to disappear at high stress along the b and c axes. Intensive and extensive barocaloric effects near the structural phase transitions were found to be comparable with the caloric parameters of some ferroelectrics, ferromagnets and antiferromagnets.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Abramova G. M., Pankrats A. I., Petrakovskii G. A., Rasch JCE, Boehm M., Vorotynov A. M., Tugarinov V. I., Szumszak R., Bovina A. F., Vasil'ev V.
Заглавие : Electron spin resonance in CuCrS(2) chrome-copper disulphides synthesized by different methods
Разночтения заглавия :авие SCOPUS: Electron spin resonance in CuCrS 2 chrome-copper disulphides synthesized by different methods
Место публикации : J. Appl. Phys.: AMER INST PHYSICS, 2010. - Vol. 107, Is. 9. - Ст.93914. - ISSN 0021-8979, DOI 10.1063/1.3374679
Примечания : Cited References: 13
Предметные рубрики: COLOSSAL MAGNETORESISTANCE
PHYSICAL-PROPERTIES
TRANSITION
Ключевые слова (''Своб.индексиров.''): chemical vapor transport--electron spin resonance--ferromagnets--g-values--magnetic transitions--polycrystalline--synthesis method--temperature range--astatine--paramagnetism--resonance--single crystals--spin dynamics--crystal impurities
Аннотация: The electron spin resonance (ESR) in CuCrS(2) disulphides is found to be strongly dependent on a synthesis method used. At a temperature of 300 K, a polycrystalline CuCrS(2) sample is paramagnetic with a g-value of 1.95 at 40 K, it undergoes the magnetic transition. In the temperature range 4.2-290 K, a single-crystal sample prepared by a chemical vapor transport method exhibits the ESR features typical of a ferromagnet. It is shown that these features are related to the presence of a small amount of the single-crystal CuCr(2)S(4) impurity in the CuCrS(2) single crystal. (C) 2010 American Institute of Physics. [doi:10.1063/1.3374679]
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Chzhan A. V.
Заглавие : Formation of inhomogeneous magnetic structures in weak ferromagnets with rhombohedral symmetry
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2008. - Vol. 50, Is. 6. - P1110-1113. - ISSN 1063-7834, DOI 10.1134/S1063783408060188
Примечания : Cited References: 8
Предметные рубрики: FEBO3
Аннотация: A model of formation of inhomogeneous magnetic structures in weak ferromagnets with rhombohedral symmetry is proposed. This model is based on the general theory of ferromagnetism in these compounds. The quantitative calculations of the dependence of the period of magnetic inhomogeneities on the parameters of the samples are presented and compared with experimental data.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ignatchenko V. A., Felk V. A.
Заглавие : Exchange narrowing of magnetic resonance linewidths in inhomogeneous ferromagnets
Место публикации : Phys. Rev. B: AMERICAN PHYSICAL SOC, 2005. - Vol. 71, Is. 9. - Ст.94417. - ISSN 1098-0121, DOI 10.1103/PhysRevB.71.094417
Примечания : Cited References: 32
Предметные рубрики: AMORPHOUS FERROMAGNETS
RANDOM ANISOTROPY
NANOCRYSTALLINE
CRYSTALS
ALLOYS
Ключевые слова (''Своб.индексиров.''): ferromagnetic material--anisotropy--article--calculation--correlation analysis--crystal structure--magnetism--mathematical analysis--nanotechnology--nuclear magnetic resonance
Аннотация: The theory of exchange narrowing of ferromagnetic and spin-wave resonance linewidths in ferromagnets with the randomly inhomogeneous magnetic anisotropy is developed. The calculation is carried out by the method of averaged Green functions in the framework of the coherent potential approximation (CPA). One- and three-dimensional inhomogeneities with an arbitrary correlation wave number k(c) are considered (r(c)=k(c)(-1) is the correlation radius of the inhomogeneities). The method of the approximate solution of the CPA equation is proposed which has the quick convergence. Effects of exchange narrowing of the magnetic resonance lines and shifts of these lines are calculated in the whole region of the values of the correlation wave number k(c). The approximate analytical expressions for the linewidth of the FMR in the limiting cases of the small and large k(c) are obtained. Large narrowing of the FMR and spin-wave linewidths with the decrease of the correlation, radius of inhomogeneities is the substantiation. of the main advantage of nanocrystalline and amorphous materials over usual polycrystals when they are used at high frequency devices.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Komogortsev S. V., Iskhakov R. S.
Заглавие : Magnetization curve and magnetic correlations in a nanochain of ferromagnetic grains with random anisotropy
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2005. - Vol. 47, Is. 3. - P495-501. - ISSN 1063-7834, DOI 10.1134/1.1884711
Примечания : Cited References: 31
Предметные рубрики: NANOCRYSTALLINE FERROMAGNETS
AMORPHOUS FERROMAGNETS
FIELD
MODEL
MICROSTRUCTURE
SIMULATIONS
DEPENDENCE
SYMMETRY
SYSTEM
MEDIA
Аннотация: The magnetization curve and magnetization correlation function are calculated for a ferromagnetic chain of single-domain nanoparticles with a randomly oriented anisotropy axis for different ratios between the exchange correlation and anisotropy energies. It is shown that the coercive force decreases as the exchange correlations increase. For strong exchange correlations, the magnetization curve is described by the following three successive magnetization processes as the applied field is increased: (i) nonuniform rotation of the magnetization of stochastic domains, (ii) collapse of the magnetic solitons, and (iii) nonuniform rotation of exchange-correlated magnetization vectors of the nanoparticles. For high fields, the calculated correlation function of the transverse magnetization components coincides with that predicted from linear theory. At low and zero fields, the main parameters of the correlation function (the variance and correlation radius) tend to certain finite values rather than diverge (as is the case in linear theory). The irreversible variation in the magnetization at low fields (the hysteresis loop) and the hysteresis of the main parameters of the correlation function are calculated. (c) 2005 Pleiades Publishing, Inc.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Frolov G. I.
Заглавие : Magnetic properties of 3d-metal nanocrystalline films
Место публикации : Tech. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2004. - Vol. 49, Is. 7. - P909-915. - ISSN 1063-7842, DOI 10.1134/1.1778867
Примечания : Cited References: 34
Предметные рубрики: ULTRAFINE GRAIN-STRUCTURE
SIZE DEPENDENCE
FERROMAGNETS
COERCIVITY
SYSTEMS
DENSITY
Аннотация: The problem of designing high-resistivity soft magnetic materials based on 3d-metal nanocrystalline films is discussed. To increase the electrical resistivity, nanogranular composites are proposed; they consist of superparamagnetic particles embedded into a dielectric matrix. To obtain the required soft magnetic properties in such composites, it is necessary to realize magnetic ordering due to the effects of magnetic interaction between nanoparticles. As an example, magnetic films that exhibit good high-frequency properties in a range up to several hundreds of megahertz are presented. (C) 2004 MAIK "Nauka / Interperiodica".
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Iskhakov R. S., Ignatchenko V. A., Komogortsev S. V., Balaev A. D.
Заглавие : Study of magnetic correlations in nanostructured ferromagnets by correlation magnetometry
Место публикации : JETP Letters. - 2003. - Vol. 78, Is. 10. - P.646-650. - ISSN 0021-3640, DOI 10.1134/1.1644310
Примечания : Cited References: 20
Предметные рубрики: AMORPHOUS FERROMAGNETS
RANDOM ANISOTROPY
NANOCRYSTALLINE
SYSTEM
RIPPLE
Аннотация: We propose a theoretically justified experimental magnetometric technique for determining the size of stochastic domains spontaneously formed in the spin system of nanostructured ferromagnets and for evaluating the effective anisotropy in these magnetically correlated regions. The method is based on monitoring the DeltaM similar to H (-2) relationship in the low-field part of the integral magnetization curve. (C) 2003 MAIK "Nauka/Interperiodica".
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Iskhakov R. S., Komogortsev S. V., Balaev A. D., Chekanova L. A.
Заглавие : Multilayer Co/Pd films with nanocrystalline and amorphous Co layers: Coercive force, random anisotropy, and exchange coupling of grains
Место публикации : Tech. Phys. Lett.: AMER INST PHYSICS, 2002. - Vol. 28, Is. 9. - P725-728. - ISSN 1063-7850, DOI 10.1134/1.1511766
Примечания : Cited References: 14
Предметные рубрики: MAGNETIC-PROPERTIES
SIZE DEPENDENCE
ALLOYS
FERROMAGNETS
FE
Аннотация: The values of saturation magnetization M-s, exchange coupling constant A, local magnetic anisotropy field H-a , random anisotropy correlation radius R-c, and coercive force H-c were independently measured for multilayer Co/Pd films with nanocrystalline and amorphous Co layers. It is shown that variation of the coercive force H-c(t(Co)) as a function of the cobalt layer thickness t(Co) is related to changes in characteristics of the magnetic microstructure. The main factor determining changes in the ferromagnetic correlation radius R-f and the average anisotropy [K] of a magnetic block in multilayer Co/Pd films is variation of exchange coupling constant A(t(Co)). (C) 2002 MAIK "Nauka/Interperiodica".
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Iskhakov R. S., Komogortsev S. V., Balaev A. D., Chekanova L. A.
Заглавие : Dimensionality of a system of exchange-coupled grains and magnetic properties of nanocrystalline and amorphous ferromagnets
Место публикации : JETP Letters. - 2000. - Vol. 72, Is. 6. - P.304-307. - ISSN 0021-3640, DOI 10.1134/1.1328443
Примечания : Cited References: 15
Предметные рубрики: RANDOM ANISOTROPY
FILMS
IRON
SIZE
Аннотация: Characteristics of random magnetic anisotropy in ferromagnetic films of amorphous Co90P10 and nanocrystalline Ni75C25 , Fe80B4C16 , and Co80C20 alloys and also in multilayer films [Co93P7(x)/Pd(14 Angstrom)](20) and [Co90P10(x)/Pd(14 Angstrom)](20) obtained by various technological procedures were studied experimentally. It was found that the spatial dimensionality (d) of the system of ferromagnetically coupled grains (2R(c)) in the materials under study determined the exponent in the power dependence of the approach of magnetization to saturation in the region of fields H 2A / MRc2. The dependence DeltaM similar to H-1/2 was observed for nanocrystalline and amorphous films with a three-dimensional grain arrangement. The approach to saturation in multilayer films with a two-dimensional grain arrangement in an individual magnetic layer follows the law DeltaM similar to H-1. The main micromagnetic characteristics of random anisotropy, such as the ferromagnetic correlation radius R-f and the average anisotropy [K] of a ferromagnetic domain with a size of 2R(f) , were determined for multilayer Co/Pd films. Correlation was found between the coercive field and these characteristics of random anisotropy. (C) 2000 MAIK "Nauka / Interperiodica".
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Iskhakov R. S., Komogortsev S. V., Moroz Z. M., Shalygina E. E.
Заглавие : Characteristics of the magnetic microstructure of amorphous and nanocrystalline ferromagnets with a random anisotropy: Theoretical estimates and experiment
Место публикации : JETP Letters. - 2000. - Vol. 72, Is. 12. - P.603-607. - ISSN 0021-3640, DOI 10.1134/1.1351199
Примечания : Cited References: 22
Предметные рубрики: ALLOYS
Аннотация: An experimental determination (both direct and indirect) of the characteristics of the magnetic microstructure, namely, the ferromagnetic correlation radius R-f and the rms fluctuation of the mean anisotropy D-1/2H-a, is performed for amorphous and nanocrystalline ferromagnets with a random anisotropy characterized by the quantities R-c and (DHa)-H-1/2, respectively. The magnetization curves of amorphous and nanocrystalline ferromagnets are found to exhibit a dependence on H that is caused by the alignment of the magnetizations of individual magnetic blocks with the field. (C) 2000 MAIK "Nauka/Interperiodica".
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gavrichkov V. A., Ovchinnikov S. G.
Заглавие : Characteristic features of the extrinsic electric resistance in ferromagnets with low carrier density
Место публикации : Phys. Solid State: AMER INST PHYSICS, 1999. - Vol. 41, Is. 1. - P59-66. - ISSN 1063-7834, DOI 10.1134/1.1130731
Примечания : Cited References: 26
Предметные рубрики: QUANTUM TEMPERATURE OSCILLATIONS
MAGNETIC SEMICONDUCTORS
HGCR2SE4
RESISTIVITY
FILMS
Аннотация: Switching from simple semiconductors to more complicated chemical compositions, we encounter mainly nonstoichiometric or undoped compounds. Combined with other characteristic features of d(f) compounds, this can lead, together with the ordinary scattering by spin disorder in magnetic semiconductors, to an unusual impurity contribution to the total scattering of carriers even in intrinsic semiconductors. A unique scheme for calculating the energy structure of the conduction-band bottom of a ferromagnetic semiconductor and the temperature and field dependences of the impurity contribution to the resistivity is proposed on the basis of a model Hamiltonian. The computed magnetoresistance ratio is negative and has a maximum near T-c. A qualitative comparison is made between the results and the experimental temperature dependences of the Hall mobility and magnetoresistance ratio in the ternary semiconductor n-HgCr2Se4, which is nonstoichiometric with respect to the chalcogen. To identify previously unobserved temperature oscillations of the resistance, a careful analysis is made of the low-temperature part of the resistance using the relations obtained. (C) 1999 American Institute of Physics. [S1063-7834(99)01701-3].
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