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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G.
Заглавие : Metallization and spin crossover in Magnesiowustite (Mg1-x Fe (x) O) at high pressures
Разночтения заглавия :авие SCOPUS: Metallization and spin crossover in Magnesiowustite (Mg 1 - xFe xO) at high pressures
Место публикации : JETP Letters. - 2011. - Vol. 94, Is. 3. - P.192-196. - ISSN 0021-3640, DOI 10.1134/S0021364011150094
Примечания : Cited References: 25. - The work was supported by the Division of Physical Sciences, Russian Academy of Sciences (program "Strong Electron Correlations"), the Siberian and Ural Branches, Russian Academy of Sciences (joint project no. 40), the Russian Foundation for Basic Research (project nos. 09-02-00171 and 10-02-00251), and the Ministry of Education and Sciences (project no. KG P891, federal program "Human Resources"). I am grateful to Yu.S. Orlov, N.V. Lishneva, and I.A. Makarov for their assistance in this work.
Предметные рубрики: EARTHS MANTLE
TRANSITION
Аннотация: The pressure-temperature phase diagram of magnesiowustite has been constructed using the many-electron LDA+GTB approach. The phase diagram includes a quantum critical point at P (c) = 55 GPa and has a symmetrical distribution of high-spin and low-spin states. The existence of a metallic state in a narrow temperature range above the critical point is predicted.
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2.

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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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Abramova G. M., Hanzawa A., Kagayama T., Mita Y., Eremin E. V., Zeer G. M., Zharkov S. M., Ovchinnikov S. G.
Заглавие : Pressure-induced metallization of the Mott insulator FeXMn1−XS system
Место публикации : J. Magn. Magn. Mater. - 2018. - Vol. 465. - P.775-779. - ISSN 03048853 (ISSN), DOI 10.1016/j.jmmm.2018.05.056
Примечания : Cited References: 23. - This study was supported by the KAKENHI JSPS, project no. 18540317.
Ключевые слова (''Своб.индексиров.''): correlated electron systems--metal-insulator transitions--high pressure and low temperature
Аннотация: Electrical resistivity of the FeXMn1−XS (0 ≤ X ≤ 0.29) single crystals based on the Mott insulator α-MnS is experimentally studied in the temperature range of 2–300 K at ambient pressure (P = 0) and at high (up to 30 GPa) hydrostatic pressures for x = 0.12. The electron subsystem of FeXMn1−XS undergoes insulator-to-metal transitions indicated by a resistivity drop by a factor of 106 with an increase in the chemical pressure (X) due to the cation substitution under ambient conditions and at the hydrostatic pressure (PC = 27 ± 5 GPa) for x = 0.12. The results obtained show that the hydrostatic pressure - and cation-substitution induced insulator-to-metal transitions in the α-MnS-based Mott compounds have similar mechanisms. The dependence of the critical hydrostatic pressure PC on the Fe content in FeXMn1−XS is established.
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Lyubutin I. S., Ovchinnikov S. G., Gavriliuk A. G., Struzhkin V. V.
Заглавие : Spin-crossover-induced Mott transition and the other scenarios of metallization in 3d(n) metal compounds
Разночтения заглавия :авие SCOPUS: Spin-crossover-induced Mott transition and the other scenarios of metallization in 3 dn metal compounds
Место публикации : Phys. Rev. B: AMER PHYSICAL SOC, 2009. - Vol. 79, Is. 8. - Ст.85125. - ISSN 1098-0121, DOI 10.1103/PhysRevB.79.085125
Примечания : Cited References: 41
Предметные рубрики: RARE-EARTH ORTHOFERRITES
NARROW ENERGY BANDS
HIGH-PRESSURE
MAGNETIC COLLAPSE
ELECTRON CORRELATIONS
PHASE-TRANSITION
STATE
Y3FE5O12
OXIDES
EQUATION
Ключевые слова (''Своб.индексиров.''): bismuth compounds--hubbard model--localised states--metal-insulator transition--metallisation--spin systems
Аннотация: A different "Hubbard energy control" mechanism of the insulator-metal transition (IMT) in Mott-Hubbard insulators is discussed. This mechanism can be initiated by the lattice compression and it is driven by a spin crossover of 3d(5) ions from the high-spin state to the low-spin state. The spin crossover suppresses the effective Hubbard parameter U-eff down to the value enabling the insulator-metal transition according to the Mott mechanism U-eff/W approximate to 1. The classification of possible scenarios of metallization in the other 3d(n) metal compounds is also performed.
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Plotkin V. V., Dyad'kov P. G., Ovchinnikov S. G.
Заглавие : Detecting a magnesiowustite phase transition in the lower mantle by inversion of geomagnetic data
Коллективы : Siberian Branch of the Russian Academy of Sciences [96]
Место публикации : Russ. Geol. Geophys.: Elsevier Science, 2014. - Vol. 55, Is. 9. - P.1138-1145. - ISSN 1068-7971, DOI 10.1016/j.rgg.2014.08.009. - ISSN 1878-030X
Примечания : Cited References: 26. - The study was supported by the Siberian Branch of the Russian Academy of Sciences (interdisciplinary integration project no. 96).
Предметные рубрики: ELECTRICAL-CONDUCTIVITY
SATELLITE MEASUREMENTS
EARTHS MANTLE
GLOBAL MVS
INDUCTION
FIELD
METALLIZATION
Ключевые слова (''Своб.индексиров.''): magnesiowustite--metallic state--phase transition--lower mantle--conductivity--geomagnetic variations--global network
Аннотация: Global geomagnetic data are inverted for detecting a high-conductivity layer at depths of 1500-2000 km to test the hypothesis of a magnesiowustite phase transition in the lower mantle. We present the results of processing of both synthetic and global data-average monthly values of the geomagnetic field from 1920 to 2009. The inverted global data are consistent with the possible existence of a high-conductivity layer at great depths in the lower mantle.
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Plotkin V. V., Dyad'kov P. G., Ovchinnikov S. G.
Заглавие : Possible contribution of lower mantle magnesiowüstite metallization into geomagnetic data
Место публикации : Rus. Geol. Geophys.: Elsevier, 2013. - Vol. 54, Is. 3. - P.263-271. - DOI 10.1016/j.rgg.2013.02.002
Аннотация: Phase change of dielectric magnesiowüstite in the lower mantle may leave signatures in geomagnetic records of the globally distributed array of observatories. We investigate theoretically which may be the contribution of magnesiowüstite metallization to geomagnetic data and how the variations of magnetic susceptibility associated with this phase change may influence the Earth's field. The modeling is performed using spherical harmonic analysis (SHA) of mantle electromagnetic (EM) responses in observatory geomagnetic data at periods of decades, 11 years, 1 year, and 27 days. The existence of a lower mantle conductor is checked against monthly means of real observatory records from 1920 through 2009 obtained by preliminary processing.
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Плоткин, Валерий Викторович, Дядьков, Петр Георгиевич, Овчинников, Сергей Геннадьевич
Заглавие : Возможный вклад фазового перехода магнезиовюстита в нижней мантии земли в геомагнитные данные
Место публикации : Геол. и геофиз. - 2013. - Т. 54, № 3. - С. 345-356
Аннотация: Рассматриваются возможные проявления в геомагнитных данных, регистрируемых мировой сетью обсерваторий, перехода магнезиовюстита из полупроводникового состояния в металлическое в нижней мантии. В частности, даны теоретические оценки предполагаемых возмущений многолетних, циклических (11-летних), годовых и 27-дневных геомагнитных вариаций. Теоретически рассмотрены эффекты ослабления магнитного поля Земли, вызываемые изменениями магнитной восприимчивости при фазовых переходах магнезиовюстита. Приведены также предварительные результаты обработки данных мировой сети — среднемесячных значений геомагнитного поля с 1920 по 2009 г.
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Lyubutin I. S., Ovchinnikov S. G.
Заглавие : Spin crossovers in Mott-Hubbard insulators at high pressures
Коллективы : Moscow International Symposium on Magnetism
Место публикации : J. Magn. Magn. Mater.: Elsevier Science BV, 2012. - Vol. 324, Is. 21. - P.3538-3541. - ISSN 0304-8853, DOI 10.1016/j.jmmm.2012.02.084
Примечания : Cited References: 16. - We acknowledge the help and discussions with Drs. A.G. Gavriliuk, V.V. Struzkin and J.F. Lin. Supports by RFBR (Grants # 09-02-00171, 10-02-00251, # 11-02-00636, # 11-02-00291, # 11-02-12089) and by the RAS Program "Strongly correlated electronic systems" are acknowledged.
Предметные рубрики: ELECTRONIC-TRANSITION
MAGNETIC COLLAPSE
PHASE-TRANSFORMATIONS
BIFEO3 CRYSTAL
METAL-OXIDES
METALLIZATION
Ключевые слова (''Своб.индексиров.''): electronic structure--spin crossover--high pressure--magnetic transition
Аннотация: The high-pressure induced phase transitions initiated by electronic transition in 3d ions from the high-spin (HS) to the low-spin (LS) state (HS-LS spin-crossover) are considered. Behavior of the system with d(6) electronic configuration is investigated in the ground state of zero temperature and critical pressure P-c. Magnetic properties of the Mott-Hubbard insulator (Mg1-xFex)O are studied in the vicinity of the quantum critical point (T=0, P-c). At the critical pressure of spin crossover P-c, the spin gap energy epsilon(S) between HS and LS states is zero. The quantum spins fluctuations HS double left right arrow LS do not require any energy, and the antiferromagnetism is destroyed in the quantum critical point by the first order transition. (C) 2012 Published by Elsevier B.V.
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mita Y., Kagayama T., Abramova G. M., Petrakovskii G. A., Sokolov V.V.
Заглавие : Metallic transition of the colossal magnetoresistance material FexMn1-xS (x= 0.18) under high pressure
Место публикации : J. Korean Phys. Soc. - 2013. - Vol. 63, Is. 3. - P.325-328. - ISSN 0374-4884, DOI 10.3938/jkps.63.325
Ключевые слова (''Своб.индексиров.''): metallization--mott insulator--pressure
Аннотация: A pressure-induced phase transition in the colossal magnetoresistance (CMR) material Fe0.18Mn0.82S was studied by using infrared (IR) reflection and X-ray diffraction (XRD) at pressures up to 40 GPa at room temperature. XRD shows that the crystal structure of this sample is a NaCl-type structure at ambient pressure, that a structural change starts around 17 GPa, and that a mixed phase mixed between the NaCl-type low-pressure phase and an unknown structure high pressure phase continues up to around 25 GPa. On the other hand, the IR reflectivity increases with increasing pressure from 15 GPa and becomes remarkably high around 20 GPa. The spectra do not show any changes from 30 GPa. From these results, we conclude that the phase transition of Fe0.18Mn0.82S at room temperature starts around 15 GPa and is completed around 30 GPa and that the high-pressure phase is not a band-overlapping semimetal but a true metal. В© 2013 The Korean Physical Society.
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