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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Korshunov M. M., Efremov D. V., Golubov A. A., Dolgov O. V.
Заглавие : Unexpected impact of magnetic disorder on multiband superconductivity
Коллективы : Dynasty Foundation; ICFPM; Ministry of Education and Science of the Russian Federation [14Y26.31.0007]; RFBR [12-02-31534, 13-02-01395]; Leading Scientific Schools of the Russian Federation [NSh-2886.2014.2]; DFG [1458]; EU-Japan
Место публикации : Phys. Rev. B: American Physical Society, 2014. - Vol. 90, Is. 13. - ISSN 1098-0121, DOI 10.1103/PhysRevB.90.134517. - ISSN 1550-235X
Примечания : Cited References: 41. - The authors are grateful to S.-L. Drechsler, P.J. Hirschfeld, K. Kikoin, and S.G. Ovchinnikov for useful discussions. We acknowledge partial support by the Dynasty Foundation and ICFPM (MMK), the Ministry of Education and Science of the Russian Federation (Grant No. 14Y26.31.0007), RFBR (Grant Nos. 12-02-31534 and 13-02-01395), President Grant for Government Support of the Leading Scientific Schools of the Russian Federation (NSh-2886.2014.2), DFG Priority Program 1458, and FP7 EU-Japan program IRON SEA.
Предметные рубрики: HIGH-TEMPERATURE SUPERCONDUCTIVITY
PARAMAGNETIC IMPURITIES
IRON
CONDUCTIVITY
ALLOYS
Аннотация: We analyze how the magnetic disorder affects the properties of the two-band s± and s++ models, which are the subject of discussions regarding iron-based superconductors and other multiband systems like MgB2. We show that there are several cases when the transition temperature Tc is not fully suppressed by magnetic impurities in contrast to the Abrikosov-Gor'kov theory, but a saturation of Tc takes place in the regime of strong disorder. These cases are: (1) the purely interband impurity scattering and (2) the unitary scattering limit. We show that in the former case the s± gap is preserved, while the s++ state transforms into the s± state with increasing magnetic disorder. For case (2), the gap structure remains intact.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Togushova, Yu. N., Shestakov V. A., Korshunov M. M.
Заглавие : Impurity-induced smearing of the spin resonance peak in Fe-based superconductors
Коллективы : RFBR [13-02-01395]; President Grant for Government Support of the Leading Scientific Schools of the Russian Federation [NSh-2886.2014.2]; Ministry of education and science of Russia [GF-2, SFU]
Место публикации : J. Low Temp. Phys.: Springer/Plenum Publishers, 2016. - Vol. 185, Is. 5-6. - P.481-487. - ISSN 0022-2291, DOI 10.1007/s10909-016-1577-x. - ISSN 1573-7357(eISSN)
Примечания : Cited References:25. - We acknowledge partial support by the RFBR (Grant 13-02-01395), President Grant for Government Support of the Leading Scientific Schools of the Russian Federation (NSh-2886.2014.2), and The Ministry of education and science of Russia (GF-2, SFU).
Предметные рубрики: HIGH-TEMPERATURE SUPERCONDUCTIVITY
ELECTRONIC-STRUCTURE
IRON
Ключевые слова (''Своб.индексиров.''): fe-based superconductors--spin resonance peak--spin-orbit coupling--impurity scattering
Аннотация: The spin resonance peak in the iron-based superconductors is observed in inelastic neutron scattering experiments and agrees well with predicted results for the extended s-wave (s±) gap symmetry. On the basis of four-band and three-orbital tight-binding models we study the effect of nonmagnetic disorder on the resonance peak. Spin susceptibility is calculated in the random-phase approximation with the renormalization of the quasiparticle self-energy due to the impurity scattering in the static Born approximation. We find that the spin resonance becomes broader with the increase of disorder and its energy shifts to higher frequencies. For the same amount of disorder the spin response in the s± state is still distinct from that of the s++ state.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bataleva Yu. V., Palyanov Y. N., Borzdov Y. M., Bayukov O. A., Sobolev N. V.
Заглавие : The formation of graphite upon the interaction of subducted carbonates and sulfur with metal-bearing rocks of the lithospheric mantle
Место публикации : Dokl. Earth Sci.: MAIK Nauka-Interperiodica / Springer, 2016. - Vol. 466, Is. 1. - P.88-91. - ISSN 1028334X (ISSN), DOI 10.1134/S1028334X16010190
Примечания : Cited References: 15. - This study was supported by the Russian Science Foundation (project no. 14-27-00054).
Предметные рубрики: Diamond formation
Silicon
Iron
Аннотация: Experimental studies of the Fe0–(Mg, Ca)CO3–S system were carried out during 18–20 h at 6.3 GPa, 900–1400°C. It is shown that the major processes resulting in the formation of free carbon include reduction of carbonates upon redox interaction with Fe0 (or Fe3C), extraction of carbon from iron carbide upon interaction with a sulfur melt/fluid, and reduction of the carbonate melt by Fe–S and Fe⎯S–C melts. Reconstruction of the processes of graphite formation indicates that carbonates and iron carbide may be potential sources of carbon under the conditions of subduction, and participation of the sulfur melt/fluid may result in the formation of mantle sulfides. © 2016, Pleiades Publishing, Ltd.
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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 журнала
Шифр издания :
Автор(ы) : Balaev D. A., Yakushkin S. S., Dubrovskii A. A., Bukhtiyarova G. A., Shaikhutdinov K. A., Martyanov O. N.
Заглавие : Study of the high-coercivity material based on ε-Fe2O3 nanoparticles in the silica gel matrix
Место публикации : Tech. Phys. Lett.: MAIK Nauka-Interperiodica / Springer, 2016. - Vol. 42, Is. 4. - P.347-350. - ISSN 10637850 (ISSN), DOI 10.1134/S1063785016040039
Примечания : Cited References: 17. - This study was supported by the Federal Agency for Scientific Organizations of Russia (base budget financing no. V.44.1.15), the Scientific and Educational Center of Energy-Efficient Catalysis at the Novosibirsk State University, and the Russian Foundation for Basic Research (project no. 15-32-50919).
Предметные рубрики: Phase
Field
State
Oxide
Iron
Аннотация: We report the results of investigations of ε-Fe2O3 magnetic nanoparticles obtained by incipient wetness impregnation of silica gel. It was established that the obtained samples with an iron content of 12‒16% mass % containing ε-Fe2O3 nanoparticles with an average size of 10 nm on the silica gel surface exhibit a room-temperature coercivity of about 10 kOe. Along with fabrication simplicity, this fact makes the prepared samples promising for application as a magnetically hard material. © 2016, Pleiades Publishing, Ltd
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Smirnova E. S., Alekseeva O. A., Dudka A. P., Verin I. A., Artemov V. V., Bezmaternykh L. N., Gudim I. A., Frolov K. V., Lyubutin I. S.
Заглавие : Structure of Gd0.95Bi0.05Fe3(BO3)4single crystals at 293 and 90 K
Место публикации : Crystallogr. Rep.: MAIK Nauka-Interperiodica / Springer, 2016. - Vol. 61, Is. 4. - P.558-565. - ISSN 10637745 (ISSN), DOI 10.1134/S1063774516040192
Примечания : Cited References: 27. - This study was performed using the equipment of the Center of Collective Use of the Shubnikov Institute of Crystallography of the Russian Academy of Sciences and it was supported by the Ministry of Education and Science of the Russian Federation (Project RFMEFI62114X0005) and in part by the Russian Foundation for Basic Research (Grant nos. 14-02-00483 and 14-02-00307) and the Federal Program on Support of Leading Scientific Schools (Grant no. NSh-6617.2016.5).
Предметные рубрики: TRIGONAL GdFe3(BO3)4
PHASE-TRANSITIONS
IRON
Аннотация: The structure of GdFe3(BO3)4 single crystals has been studied by X-ray diffraction at 293 and 90 K. The crystals are grown from a flux in the Bi2Mo3O12–B2O3–Li2MoO4–Gd2O3–Fe2O3 system. The results of chemical analysis and structural study show that these crystals contain bismuth as an impurity. It is found that bismuth atoms are located at gadolinium sites in the structure. A decrease in the temperature is accompanied by a lowering of the symmetry from sp. gr. R32 (at 293 K) to sp. gr. P3121 (at 90 K). The presence of two types of iron chains with different geometries at 90 K promotes a change in the magnetic properties of these crystals with a decrease in the temperature. © 2016, Pleiades Publishing, Inc.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Ovchinnikova T. M., Plotkin V. V., Dyad'kov P. G.
Заглавие : Spin crossover and Mott-Hubbard transition under high pressure and high temperature in the low mantle of the Earth
Коллективы : International conference on interaction of intense energy fluxes , International Conference on Interaction of Intense Energy Fluxes with Matter (XXX; 1–6 March 2015; Elbrus, Kabardino-Balkaria, Russia)
Место публикации : J. Phys.: Conf. Ser./ International conference on interaction of intense energy fluxes (30 ; 2015 ; March ; 01-06): IOP Publishing, 2015. - Vol. 653. - Ст.012095. - ISSN 1742-6588, DOI 10.1088/1742-6596/653/1/012095
Примечания : Cited References:22
Предметные рубрики: PHASE-TRANSITION
GEOMAGNETIC DATA
MAGNESIOWUSTITE
IRON
METALLIZATION
LAYER
Аннотация: Effect of high pressure induced spin crossover on the magnetic, electronic and structural properties of the minerals forming the Earth's low mantle is discussed. The low temperature P, T phase diagram of ferropericlase has the quantum phase transition point P = 56 GPa at T = 0 confirmed recently by the synchrotron Mossbauer spectroscopy. The LDA+GTB calculated phase diagram describes the experimental data. Its extension to the high temperature resulted earlier in prediction of the metallic properties of the Earth's mantle at the depth 1400 km h 1800 km. Estimation of the electrical conductivity based on the percolation theory is given. We discuss also the thermodynamic properties and structural anomalies resulting from the spin crossover and metal insulator transition and compare them with the experimental seismic and geomagnetic field data.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Myagkov V. G., Bayukov O. A., Bykova L. E., Zhigalov V. S., Bondarenko G. N.
Заглавие : Solid-state synthesis in Ni/Fe/MgO(001) epitaxial thin films
Место публикации :. - Vol. 80, Is. 7. - P.487-490. - ISSN 0021-3640, DOI 10.1134/1.1839296
Примечания : Cited References: 34
Предметные рубрики: HIGH-TEMPERATURE SYNTHESIS
BINARY DIFFUSION COUPLES
MARTENSITIC TRANSFORMATIONS
PHASE-FORMATION
MAGNETIC-PROPERTIES
SPIN DYNAMICS
INVAR-ALLOYS
IRON
TRANSITION
NUCLEATION
Аннотация: Solid-state synthesis in Ni/Fe/MgO(001) bilayer epitaxial thin films has been studied experimentally. The phase sequence Fe/Ni -- (similar to350degreesC)Ni(3)Fe -- (similar to400degreesC)NiFe -- (similar to550degreesC)gamma(par) is formed as the annealing temperature increases. The crystal structure in the invar region consists of epitaxially intergrown single-crystal blocks consisting of the paramagnetic gamma(par) and ferromagnetic NiFe phases, which satisfy the orientation relationship [100](001)NiFe parallel to [100](001)gamma(par). It has been shown that the nucleation temperatures of the Ni(3)Fe, NiFe, and gamma(par) phases coincide with the temperatures of solid-state transformations in the Ni-Fe system. (C) 2004 MAIK "Nauka/Interperiodica".
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Dubrovskiy A. A., Balaev A. D., Shaykhutdinov K. A., Bayukov O. A., Pletnev O. N., Yakushkin S. S., Bukhtiyarova G. A., Martyanov O. N.
Заглавие : Size effects in the magnetic properties of ε-Fe2O3 nanoparticles
Место публикации : J. Appl. Phys.: American Institute of Physics, 2015. - Vol. 118, Is. 21. - Ст.213901. - ISSN 00218979 (ISSN), DOI 10.1063/1.4936838
Примечания : Cited References: 41. - We are grateful to Professor Yu. L. Raikher for useful discussions and M. A. Kazakova for the help in sample preparationThis work was supported by Russian Federal Agency of Scientific Organizations (Project No. V.44.1.15) and scientific and educational center of energy-efficient catalysis of NSU
Предметные рубрики: FERROMAGNETIC-RESONANCE
OXIDE NANOPARTICLES
WAVE ABSORBER
IRON
TRANSITION
TEMPERATURE
PARTICLES
PHASE
FNANOWIRES
FIELD
Аннотация: We report the results of comparative analysis of magnetic properties of the systems based on ε-Fe2O3, nanoparticles with different average sizes (from ∼3 to 9 nm) and dispersions. The experimental data for nanoparticles higher than 6-8 nm in size are consistent with the available data, specifically, the transition to the magnetically ordered state occurs at a temperature of ∼500 K and the anomalies of magnetic properties observed in the range of 80-150 K correspond to the magnetic transition. At the same time, Mossbauer and ferromagnetic resonance spectroscopy data as well as the results of static magnetic measurements show that at room temperature all the investigated samples contain ε-Fe2O3 particles that exhibit the superparamagnetic behavior. It was established that the magnetic properties of nanoparticles significantly change with a decrease in their size to ∼6 nm. According to high-resolution electron microscopy and Mossbauer spectroscopy data, the particle structure can be attributed to the ε-modification of trivalent iron oxide; meanwhile, the temperature of the magnetic order onset in these particles is increased, the well-known magnetic transition in the range of 80-150 K does not occur, the crystallographic magnetic anisotropy constant is significantly reduced, and the surface magnetic anisotropy plays a decisive role. This is apparently due to redistribution of cations over crystallographic positions with decreasing particle size, which was established using Mössbauer spectra. As the particle size is decreased and the fraction of surface atoms is increased, the contribution of an additional magnetic subsystem formed in a shell of particles smaller than ∼4 nm becomes significant, which manifests itself in the static magnetic measurements as paramagnetic contribution. © 2015 AIP Publishing LLC.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Pavlovskiy M. S., Zinenko V. I., Shinkorenko A. S.
Заглавие : Effect of a rare-earth ion on the structural instability in RFe3(BO3)4 crystals
Коллективы : Russian Science Foundation [17-72-10122]
Место публикации : JETP Letters. - 2018. - Vol. 108, Is. 2. - P.116-120. - ISSN 0021-3640, DOI 10.1134/S0021364018140114. - ISSN 1090-6487(eISSN)
Примечания : Cited References: 17. - This work was supported by the Russian Science Foundation (project no. 17-72-10122).
Предметные рубрики: Iron
GdFe3(BO3)4
Аннотация: The dynamics of the crystal lattice of RFe3(BO3)4 (R = Pr, Nd, Sm, Gd, Tb, Dy, and Ho) compounds in the high-symmetry R32 phase has been calculated. Significant changes in spectra of compounds with various rare-earth ions have been obtained only near the edge Λ point of the Brillouin zone (qΛ = 1/3(−2b1 + b2 + b3, where b1, b2, and b3 are the reciprocal lattice vectors) for acoustic oscillation branches. A decrease in the frequency of an acoustic mode at the point Λ has been revealed in all studied compounds. This frequency depends on the type of rare-earth ion and decreases from a compound with Pr to a compound with Ho down to imaginary values. Such a behavior of the frequency of the unstable acoustic mode is in good agreement with experimental data on the dependence of the temperature of the R32 → P3121 structural phase transition on the type of rare-earth ion in ferroborates.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ding Y., Haskel D., Ovchinnikov S. G., Tseng Y. C., Orlov Y. S., Lang J. C., Mao H. K.
Заглавие : Novel pressure-induced magnetic transition in magnetite (Fe(3)O(4))
Разночтения заглавия :авие SCOPUS: Novel pressure-induced magnetic transition in magnetite (Fe3O4)
Место публикации : Phys. Rev. Lett.: AMER PHYSICAL SOC, 2008. - Vol. 100, Is. 4. - Ст.45508. - ISSN 0031-9007, DOI 10.1103/PhysRevLett.100.045508
Примечания : Cited References: 39
Предметные рубрики: MULTIPLE-SCATTERING THEORY
X-RAY DICHROISM
LOWER MANTLE
VERWEY TRANSITION
K-EDGE
CIRCULAR-DICHROISM
SPIN TRANSITION
BAND-STRUCTURE
IRON
FE
Ключевые слова (''Своб.индексиров.''): emission spectroscopy--magnetoelectronics--pressure effects--synchrotron radiation--diamond anvil cell--magnetic transition--x-ray magnetic circular dichroism--magnetite
Аннотация: Fe K-edge x-ray magnetic circular dichroism of magnetite (Fe(3)O(4)) powders was measured with synchrotron radiation under variable pressure and temperature conditions in diamond anvil cell. The magnetic dichroism was observed to decrease discontinuously by similar to 50% between 12 and 16 GPa, independent of temperature. The magnetic transition is attributed to a high-spin to intermediate-spin transition of Fe(2+) ions in the octahedral sites and could account for previously observed structural and electrical anomalies in magnetite at this pressure range. The interpretation of x-ray magnetic circular dichroism data is supported by x-ray emission spectroscopy and theoretical cluster calculations.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Anshits A. G., Bayukov O. A., Anshits N. N., Pletnev O. N., Rabchevskii E. V., Vereshchagin S. N., Kondratenko E. V.
Заглавие : Nature of the active sites of ferrospheres in the oxidative condensation of methane
Коллективы : Russian Science Foundation [4-13-00289], Russian Congress on Catalysis (2; 2014 ; Oct. ; 2–5; Samara)
Место публикации : Kinet. Catal.: MAIK Nauka-Interperiodica / Springer, 2015. - Vol. 56, Is. 4. - P.523-531. - ISSN 0023, DOI 10.1134/S0023158415040023. - ISSN 16083210(eISSN)
Примечания : Cited References:37. - This work was supported by the Russian Science Foundation (grant no. 14-13-00289).
Предметные рубрики: GLASS CRYSTAL CATALYSTS
HIGH-TEMPERATURE
MOSSBAUER
MAGNETITES
MICROSPHERES
SELECTIVITY
CONVERSION
FERRITES
ASHES
IRON
Ключевые слова (''Своб.индексиров.''): oxidative condensation of methane--ferrospheres--iron spinel--mossbauer spectroscopy--structural defects
Аннотация: The catalytic properties of ferrospheres containing 76–97 wt % Fe2O3 in the oxidative condensation of methane were compared with their phase composition and the distribution of iron cations over the crystallographic positions of iron-containing phases in a steady state. It was established that the reaction route of methane oxidation changed at a Fe2O3 content of 89 wt %. Deep oxidation was the main reaction route on ferrospheres with a Fe2O3 content of 88.8 wt %. At a Fe2O3 content of ≥89 wt %, the yield of C2 hydrocarbons sharply increased and the contribution of deep oxidation decreased. The yield of C2 hydrocarbons correlated with the amount of defects in the structure of iron spinel, which are iron ions with the tetrahedral cation of Ca2+ and the octahedral cation vacancy among the nearest neighbors.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Maiti S., Korshunov M. M., Chubukov A.V.
Заглавие : Gap symmetry in KFe2As2 and the cos 4θ gap component in LiFeAs
Место публикации : Phys. Rev. B: American Physical Society, 2012. - Vol. 85, Is. 1. - Ст.14511. - ISSN 1098-0121, DOI 10.1103/PhysRevB.85.014511
Примечания : Cited References: 49. - We are thankful to S. Borisenko, S. Davis, R. Fernandes, P. Hirschfeld, I. Eremin, D. Evtushinsky, A. Kordyuk, K. Kuroki, Y. Matsuda, A. Rost, M. Vavilov, and V. Zabolotnyy for useful discussions. This work was supported by NSF-DMR-0906953 (SM and AVC) and by the Humboldt Foundation (AVC). MMK is grateful for support from RFBR (Grant No. 09-02-00127), the Presidium of RAS program N5.7, the FCP Scientific and Research and Educational Personnel of Innovative Russia for 2009-2013 (GK P891 and GK16.740.12.0731), and the President of Russia (Grant No. MK-1683.2010.2).
Предметные рубрики: SUPERCONDUCTING GAPS
IRON
Аннотация: We revisit the issue of the gap symmetry in KFe2As2, which is an Fe pnictide superconductor with only hole pockets. Previous theoretical studies mostly argued for a d−wave gap in KFe2As2 since transport and thermodynamic measurements point to the presence of the gap nodes. However, a d-wave gap is inconsistent with recent laser-based angle-resolved photoemission measurements. We propose a scenario for a nodal s−wave superconductivity induced by a nonmagnetic intraband and interband interactions between fermions near hole pockets. The superconducting gap changes sign between the hole pockets and has cos4θ angular dependence and accidental nodes on one or several hole pockets. We argue that strong angle dependence is the consequence of near-degeneracy between interpocket and intrapocket interaction on the hole pockets. We also analyze the cos4θ angular dependence of the gap in other Fe pnictides and compare theoretical results with the photoemission experiments of LiFeAs.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Adem U., Wang L., Fausti D., Schottenhamel W., van Loosdrecht PHM, Vasiliev A., Bezmaternykh L. N., Buchner B., Hess C., Klingeler R.
Заглавие : Magnetodielectric and magnetoelastic coupling in TbFe3(BO3)(4)
Коллективы :
Разночтения заглавия :авие SCOPUS: Magnetodielectric and magnetoelastic coupling in TbFe3(BO 3)4
Место публикации : Phys. Rev. B: AMER PHYSICAL SOC, 2010. - Vol. 82, Is. 6. - Ст.64406. - ISSN 1098-0121, DOI 10.1103/PhysRevB.82.064406
Примечания : Cited References: 23. - We thank K. L. and S. G. for technical support. Work was supported by the DFG through Grants No. HE 3439/6 and No. 486 RUS 113/982/0-1.
Предметные рубрики: DIELECTRIC-CONSTANTS
IRON
GDFE3(BO3)(4)
MULTIFERROICS
TEMPERATURE
Аннотация: We have studied the magnetodielectric and magnetoelastic coupling in TbFe3(BO3)(4) single crystals by means of capacitance, magnetostriction, and Raman spectroscopy measurements. The data reveal strong magnetic field effects on the dielectric constant and on the macroscopic sample length which are associated to long-range magnetic ordering and a field-driven metamagnetic transition. We discuss the coupling of the dielectric, structural, and magnetic order parameters and attribute the origin of the magnetodielectric coupling to phonon mode shifts according to the Lyddane-Sachs-Teller relation.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Popova E. A., Tristan N., Vasiliev A. N., Temerov V. L., Bezmaternykh L. N., Leps N., Buechner B., Klingeler R.
Заглавие : Magnetization and specific heat of DyFe3(BO3)(4) single crystal
Разночтения заглавия :авие SCOPUS: Magnetization and specific heat of DyFe 3(BO 3) 4 single crystal
Место публикации : Eur. Phys. J. B: SPRINGER, 2008. - Vol. 62, Is. 2. - P123-128. - ISSN 1434-6028, DOI 10.1140/epjb/e2008-00146-5
Примечания : Cited References: 18
Предметные рубрики: IRON
NDFE3(BO3)(4)
GDFE3(BO3)(4)
Ключевые слова (''Своб.индексиров.''): antiferromagnetic orders--iron subsystems--antiferromagnetic materials--dysprosium compounds--magnetic field effects--magnetization--specific heat--thermodynamics--single crystals
Аннотация: We present thermodynamic and magnetic studies of single crystalline DyFe3(BO3)(4). The data indicate an easy axis antiferromagnetic order below T-N similar to 38 K which we attribute to the Fe subsystem. The Dy subsystem remains paramagnetic down to the lowest investigated temperatures of 2 K, but it is polarized by the Fe spins due to a f-d interaction. External magnetic field leads to a spin-flop transition in the iron subsystem as well as to superposed magnetization in the Dy subsystem. The repopulation of two low-lying Kramers doublets in Dy3+ ions results in well defined Schottky anomalies in specific heat and magnetization.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuz'min V. I., Orlov Yu. S., Zarubin A. E., Ovchinnikova T. M., Ovchinnikov S. G.
Заглавие : Magnetism in spin crossover systems: Short-range order and effects beyond the Heisenberg model
Коллективы : Russian Scientific FoundationRussian Science Foundation (RSF) [18-12-00022]
Место публикации : Phys. Rev. B. - 2019. - Vol. 100, Is. 14. - Ст.144429. - ISSN 2469-9950, DOI 10.1103/PhysRevB.100.144429. - ISSN 2469-9969(eISSN)
Примечания : Cited References: 72. - The authors thank the Russian Scientific Foundation for the financial support under Grant No. 18-12-00022.
Предметные рубрики: LOWER-MANTLE
STATE
TRANSITION
PRESSURE
IRON
SUSCEPTIBILITY
Аннотация: To study non-Heisenberg effects in the vicinity of spin crossover in strongly correlated electron systems we derive an effective low-energy Hamiltonian for the two-band Kanamori model. It contains a Heisenberg high-spin term proportional to exchange constant as well as a low-spin term proportional to spin gap parameter ɛs. Using cluster mean field theory we obtain several non-Heisenberg effects. Near the critical value of spin gap ɛcs there is a magnetic phase transition of first order. In the vicinity of ɛcs in the paramagnetic phase we observe nontrivial behavior of the Curie constant in the paramagnetic susceptibility in the wide range of temperature. Reentrant temperature behavior of nearest-neighbor spin-spin correlations is observed at ɛsɛcs. Finally, the pressure-temperature magnetic phase diagram for ferroperriclase is obtained using the effective Hamiltonian.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bartolome J., Badía-Romano L., Rubin J., Bartolome F., Varnakov S. N., Ovchinnikov S. G., Burgler D.E.
Заглавие : Magnetic properties, morphology and interfaces of (Fe/Si)n nanostructures
Коллективы : International Conference on Magnetism
Место публикации : J. Magn. Magn. Mater.: Elsevier, 2016. - Vol. 400. - P.271-275. - ISSN 03048853 (ISSN), DOI 10.1016/j.jmmm.2015.07.046
Примечания : Cited References: 43. - The financial support of the Spanish MINECOMAT2011-23791 and MAT2015-53921-R, Aragonese DGA-IMANAE34 (cofounded by Fondo Social Europeo) and European FEDER funds is acknowledged. Program of the President of the Russian Federation for the support of leading scientific schools (Scientific School 2886.2014.2), RFBR (Grant no. 13-02-01265), the Ministry of Education and Science of the Russian Federation (State contract no. 02.G25.31.0043 and State task no. 16.663.2014К)
Предметные рубрики: INTERLAYER EXCHANGE
Fe/Si(100) INTERFACE
SILICIDE FORMATION
ULTRAHIGH-VACUUM
FILMS
IRON
MAGNETORESISTANCE
SUPERLATTICES
SPECTROSCOPY
DEPOSITION
Аннотация: A systematic study of the iron–silicon interfaces formed upon preparation of (Fe/Si) multilayers has been performed by the combination of modern and powerful techniques. Samples were prepared by molecular beam epitaxy under ultrahigh vacuum onto Si wafers or single crystalline Ag(100) buffer layers grown on GaAs(100). The morphology of these films and their interfaces was studied by a combination of scanning transmission electron microscopy, X-ray reflectivity, angle resolved X-ray photoelectron spectroscopy and hard X-ray photoelectron spectroscopy. The Si-on-Fe interface thickness and roughness were determined to be 1.4(1) nm and 0.6(1) nm, respectively. Moreover, determination of the stable phases formed at both Fe-on-Si and Si-on-Fe interfaces was performed using conversion electron Mössbauer spectroscopy on multilayers with well separated Si-on-Fe and Fe-on-Si interfaces. It is shown that while a fraction of Fe remains as α-Fe, the rest has reacted with Si, forming the paramagnetic FeSi phase and a ferromagnetic Fe rich silicide. We conclude that there is an identical paramagnetic c-Fe1−xSi silicide sublayer in both Si-on-Fe and Fe-on-Si interfaces, whereas an asymmetry is revealed in the composition of the ferromagnetic silicide sublayer.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Frolov G. I., Bachina O. I., Zav'yalova M. M., Ravochkin S. I.
Заглавие : Magnetic properties of nanoparticles of 3d metals
Коллективы :
Место публикации : Tech. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2008. - Vol. 53, Is. 8. - P1059-1064. - ISSN 1063-7842, DOI 10.1134/S1063784208080136
Примечания : Cited References: 19. - This study was supported by the targeted program "Development of the Research Potential of Higher Education Institutions," grant no. RNP.2.1.1.7376.
Предметные рубрики: CLUSTERS
IRON
PARTICLES
Аннотация: The influence of size effects on the coercive force, magnetization, and Curie temperature in nanoparticles of 3d metals is considered. It is shown that experimental results obtained during the last two decades provide new information on peculiar magnetic properties of these particles.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Yakushkin S. S., Dubrovskiy A. A., Balaev A. D., Shaykhutdinov K. A., Bukhtiyarova G. A., Martyanov O. N.
Заглавие : Magnetic properties of few nanometers ɛ-Fe2O3 nanoparticles supported on the silica
Место публикации : J. Appl. Phys.: American Institute of Physics, 2012. - Vol. 111, Is. 4. - Ст.44312. - ISSN 0021-8979, DOI 10.1063/1.3686647
Примечания : Cited References: 27. - authors thank A. D. Balaev and N. V. Volkov for fruitful discussions and comments. This work was supported by Program of RAS No. 27.46.
Предметные рубрики: HIGH-TEMPERATURE
IRON
STABILIZATION
OXIDE
GEL
Аннотация: Magnetic properties of ɛ-Fe2O3nanoparticles supported on silica with the average size of few nanometers, narrow size distribution and no admixture of any other iron oxide polymorphs are investigated. The investigation of the temperature behavior of magnetization within the temperature range from 4.2 to 1000 K revealed the presence of several magnetic subsystems in the species under study. The temperatures’ behavior of the magnetic moment value indicates ferrimagnetic ordering in the ɛ-Fe2O3nanoparticles with a Curie temperature of about 800 K and points to the existence of a significant paramagnetic contribution becoming apparent at low temperatures. According to the electron spin resonance data, the particles possess superparamagnetic behavior at temperature higher ∼120 K. The model of the magnetic structure of monophase system of few nanometers ɛ-Fe2O3nanoparticles supported on silica is proposed.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Raikher Y. L., Stepanov V. I., Stolyar S. V., Ladygina V. P., Balaev D. A., Ishchenko L. A., Balasoiu M.
Заглавие : Magnetic properties of biomineral particles produced by bacteria Klebsiella oxytoca
Коллективы :
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2010. - Vol. 52, Is. 2. - P298-305. - ISSN 1063-7834, DOI 10.1134/S1063783410020125
Примечания : Cited References: 29. - This study was supported by the Russian Foundation for Basic Research (project nos. 07-02-96026, 07- 02-96017, and 08-02-00802) and performed within the framework of the Federal Target Program "Research and Research-Pedagogical Personnel of Innovation Russia for 2009-2013."
Предметные рубрики: FERRITIN
NANOPARTICLES
IRON
SUSCEPTIBILITY
FERRIHYDRITE
BEHAVIOR
FINS
Аннотация: Ferrihydrite nanoparticles (2-5 nm in size) produced by bacteria Klebsiella oxytoca in the course of biomineralization of iron salt solutions from a natural medium exhibit unique magnetic properties: they are characterized by both the antiferromagnetic order inherent in a bulk ferrihydrite and the spontaneous magnetic moment due to the decompensation of spins in sublattices of a nanoparticle. The magnetic susceptibility enhanced by the superantiferromagnetism effect and the magnetic moment independent of the magnetic field provide the possibility of magnetically controlling these natural objects. This has opened up the possibilities for their use in nanomedicine and bioengineering. The results obtained from measurements of the magnetic properties of the ferrihydrite produced by Klebsiella oxytoca in its two main crystalline modifications are reported, and the data obtained are analyzed theoretically. This has made it possible to determine numerical values of the magnetic parameters of real biomineral nanoparticles.
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