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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S., Piskunova N. I.
Заглавие : Anomalies in magnetoresistance and in the bulk modulus for ferromagnetics with four-spin exchange interaction on the Kondo lattice
Место публикации : J. Phys.: Condens. Matter: IOP PUBLISHING LTD, 2006. - Vol. 18, Is. 29. - P.6859-6868. - ISSN 0953-8984, DOI 10.1088/0953-8984/18/29/023
Примечания : Cited References: 29
Предметные рубрики: MIXED-VALENCE MANGANITES
PHASE-SEPARATION
LA1-XSRXMNO3
BEHAVIOR
PECULIARITIES
TRANSITION
Ключевые слова (''Своб.индексиров.''): elastic moduli--electric resistance--ferromagnetism--function evaluation--paramagnetism--transceivers--adiabatic approximation--kondo lattice--paramagnetic state--ring exchange--magnetoresistance
Аннотация: The temperature dependence of resistivity and the bulk modulus are calculated on the Kondo lattice, with ring exchange between localized spins, using the spin-polaron and adiabatic approximation. Peak and zero values of the bulk modulus as functions of temperature and concentration are determined below the temperature of the transition to the paramagnetic state. The effects of the nearest order between transverse spin components and a value of the ring exchange between localized spins on magnetoresistivity are estimated.
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S.
Заглавие : Anomalies in transport properties in a magnetically ordered region on a Kondo lattice
Место публикации : JETP Letters. - 2005. - Vol. 81, Is. 2. - P.66-71. - ISSN 0021-3640, DOI 10.1134/1.1887917
Примечания : Cited References: 33
Предметные рубрики: DOUBLE EXCHANGE MODEL
PHASE-SEPARATION
MANGANITES
LA1-XSRXMNO3
SYSTEMS
SHIFT
EDGE
Аннотация: The temperature dependences of resistivity and thermal emf on a Kondo lattice are calculated using the spinpolaron approximation. The peaks and sign reversal points of thermal emf as a function of temperature and concentration below the temperature of the transition to the paramagnetic state are determined. The concentration region containing the metal-insulator transition below the Curie temperature and the shift of the upper spin-polaron band are calculated. (c) 2005 Pleiades Publishing, Inc.
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S., Sitnikov M. N.
Заглавие : Magnetotransport effects in paramagnetic GdxMn1-xS
Коллективы : Russian Foundation for Basic Research [12-02-00125-a, 14-02-90010-Bel_a]
Место публикации : JETP Letters. - 2014. - Vol. 100, Is. 2. - P.95-101. - ISSN 0021-3640, DOI 10.1134/S0021364014140021. - ISSN 1090-6487
Примечания : Cited References: 12. - This work was supported by the Russian Foundation for Basic Research (project nos. 12-02-00125-a and 14-02-90010-Bel_a).
Предметные рубрики: PHASE-SEPARATION
SPINTRONICS
MANGANITES
Аннотация: The electrical resistance of GdxMn1 − xS solid solutions with x = 0.1, 0.15, and 0.2 has been measured at magnetic field H = 0.8 T and at zero magnetic field within the 100 K ˂ T ˂ 550 K temperature range. The magnetoresistance peak is observed above room temperature. On heating, the composition with x = 0.2 exhibits the change of magnetoresistance sign from positive to negative and the magnetoresistance peak near the transition to the magnetically ordered state. The experimental data are interpreted in the framework of the model involving the orbital ordering of electrons and the arising electrical polarization leading to the changes in the spectral density of states for electrons in the vicinity of the chemical potential in the applied magnetic field.
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Romanova O. B., Kretinin V. V., Aplesnin S. S., Sitnikov M. N., Udod L. V., Yanushkevich K. I.
Заглавие : Electrical properties of the polycrystalline BiFe0.95Co0.05O3 films
Коллективы : Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR); Belarusian Republican Foundation for Basic Research [20-52-00005]
Место публикации : Phys. Solid State. - 2021. - Vol. 63. Is. 6. - P.897-903. - ISSN 1063-7834, DOI 10.1134/S1063783421060184. - ISSN 1090-6460(eISSN)
Примечания : Cited References: 34. - This study was supported by the Russian Foundation for Basic Research and the Belarusian Republican Foundation for Basic Research, project no. 20-52-00005
Предметные рубрики: BiFeO3 THIN-FILMS
PHASE-SEPARATION
CRYSTAL
MODEL
Аннотация: Semiconductor BiFe0.95Co0.05O3 thin-film compounds have been synthesized by a burst technique. The film surface morphology and the effect of electronic doping via substitution of cobalt ions for trivalent iron on the optical, magnetic, and kinetic properties have been investigated in the temperature range of 77-600 K in magnetic fields of up to 12 kOe. Two electron relaxation channels have been found in the impedance spectrum in the frequency range of 0.1-1000 kHz. The negative magnetoresistance in the anomalous magnetization region and the maximum magnetoimpedance in the vicinity of the surface phase transition have been established. Using the Hall measurements, carrier types dominating in the magnetoresistance and magnetoimpedance effects have been determined. The magnetization anomalies have been explained in the model of superparamagnetic clusters and the magnetoresistance, by the carrier scattering by spin fluctuations.
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Patrin G. S., Polyakova K. P., Patrusheva T. N., Velikanov D. A.
Заглавие : Features of the magnetic properties of La0.7Sr0.3MnO3 manganite films obtained by an extraction-pyrolysis method
Разночтения заглавия :авие SCOPUS: Features of the magnetic properties of La0.7Sr 0.3MnO3 Manganite films obtained by an extraction-pyrolysis method
Место публикации : Tech. Phys. Lett.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2007. - Vol. 33, Is. 4. - P330-332. - ISSN 1063-7850, DOI 10.1134/S1063785007040177
Примечания : Cited References: 12
Предметные рубрики: PHASE-SEPARATION
MAGNETORESISTANCE
Аннотация: We have experimentally studied the magnetic properties of manganite films obtained for first time using an extraction-pyrolysis technique. It is established that the characteristics of samples significantly depend on the conditions of final annealing. The annealing at temperatures T-a 970 K is accompanied by strong thermomagmetic effects. and the resulting films possess properties similar to those of spin glasses. When the annealig temperature is increased to T-a = 1020 K, the films exhibit magnetic properties typical of ferromagnetic systems.
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Troyanchuk I. O., Bushinsky M. V., Sikolenko V., Efimov V., Volkov N. V., Tobbens D. M., Ritter C., Raveau B.
Заглавие : Ferromagnetism in single-valent manganites
Место публикации : J. Alloys Compd.: Elsevier Science, 2015. - Vol. 619. - P.719-725. - ISSN 0925-8388, DOI 10.1016/j.jallcom.2014.08.236. - ISSN 1873-4669
Примечания : Cited References: 46. - The authors would like to thank J.B. Goodenough for the fruitful discussion. This work has been supported by Belarusian Republican Foundation for Fundamental Research (Grant F14R-040).
Предметные рубрики: PHASE-SEPARATION
DOPED MANGANITES
DOUBLE EXCHANGE
DIFFRACTION
OXIDES
NMR
Ключевые слова (''Своб.индексиров.''): magnetically ordered materials--solid state reactions--exchange and superexchange--magnetic measurements--neutron diffraction
Аннотация: Structural and magnetization measurements have been performed on the La0.7Sr0.3Mn0.85 Nb 0.15 - x 5 + Mg x 2 + O3 stoichiometric compounds. With rise of the Mg2+ content the formal oxidation state manganese increases from +3 ( x = 0 ) up to +3.55 ( x = 0.15 ) . The compositions with 0 ⩽ x ≤ 0.08 undergo a structural transition from rhombohedral to orthorhombic symmetry below room temperature whereas x = 0.1 and x = 0.15 compounds are rhombohedral down to 2 K. The structural parameters evidence that the orthorhombic phase is not long-range orbitally ordered and that the structural transition is associated with a steric effect. The Mg-free compound is ferromagnetic with the Curie point of around 150 K and a magnetic moment of 3.1 μ B /Mn. The substitution of Nb5+ with Mg2+ leads to a gradual weakening of the ferromagnetic component while in the x = 0.15 compound A-type antiferromagnetic short-range order is stabilized in spite of macroscopic R 3 ¯ c symmetry. All the compositions show insulating behavior. It is suggested that ferromagnetism is originated from superexchange interactions via oxygen. Covalence enhances the positive part of the superexchange interactions whereas structural disorder induced by Nb5+ and Mg2+ ions leads to suppression of ferromagnetism.
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Volkov N. V., Petrakovskii G. A., Patrin K. G., Sablina K. A., Eremin E. V., Vasiliev V., Vasiliev A., Molokeev M. S., Boni P., Clementyev E.
Заглавие : Intrinsic inhomogeneity in a (La0.4Eu0.6)(0.7)Pb0.3MnO3 single crystal: Magnetization, transport, and electron magnetic resonance studies
Разночтения заглавия :авие SCOPUS: Intrinsic inhomogeneity in a (La0.4 Eu0.6) 0.7 Pb0.3 MnO3 single crystal: Magnetization, transport, and electron magnetic resonance studies
Место публикации : Phys. Rev. B: AMERICAN PHYSICAL SOC, 2006. - Vol. 73, Is. 10. - Ст.104401. - ISSN 1098-0121, DOI 10.1103/PhysRevB.73.104401
Примечания : Cited References: 29
Предметные рубрики: INSULATOR-METAL TRANSITION
PHASE-SEPARATION
MAGNETORESISTANCE
MANGANITES
EXCHANGE
STATE
Аннотация: Conventional magnetic and transport measurements of the melt-grown mixed-valence manganite (La0.4Eu0.6)(0.7)Pb0.3MnO3 have been supplemented by a magnetic resonance study. The experimental data support the model of two magnetic phases coexisting in the crystal volume. At a temperature T-*, which is well above Curie temperature T-C, ferromagnetic clusters appear in the sample. These ferromagnetic regions possess a higher conductivity in comparison with the paramagnetic background (majority phase). On cooling through T-C, the magnetization of the spatially confined ferromagnetic clusters of the minority phase freezes in random directions with respect to the magnetization of the ferromagnetic majority phase due to the difference of the exchange interactions at the phase boundaries from the intraphase interactions in sign and value. Such a mixed state is responsible for the observed magnetic glassylike behavior of the system that is characteristic of inhomogeneous magnets. The fluctuations of the magnetic coupling value and sign in the sample volume are related to strong competition between the ferromagnetic and antiferromagnetic exchange interactions, which, in turn, results from the quenched disorder caused by the random chemical replacement of the perovskite A site of the manganite. A phase-separation state comprised of two different ferromagnetic phases has been used to account for the colossal magnetoresistance phenomenon and the magnetic-field-driven nonlinear conduction found in the crystal.
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Y., Efremov D. V., Mar'enko M. S., Val'kov V. V.
Заглавие : Kohn-Luttinger effect and anomalous pairing in repulsive Fermi-systems at low density : Review Article
Место публикации : Low Temp. Phys.: American Institute of Physics, 2012. - Vol. 38, Is. 9. - P.874-879. - ISSN 1063-777X, DOI 10.1063/1.4752091
Примечания : Cited References: 59. - We acknowledge helpful discussions with A. V. Chubukov, A. S. Alexandrov, V. V. Kabanov, K. I. Kugel, Yu. V. Kopaev, N. M. Plakida, and N. V. Prokof'ev. M. Yu. K's work was supported by RFBR Grant No 11-02-00741-a.
Предметные рубрики: T-J MODEL
SUPERFLUID TRANSITION-TEMPERATURE
2-BAND HUBBARD-MODEL
LOW ELECTRON-DENSITY
FRACTIONAL-STATISTICS
PHASE-SEPARATION
SUPERCONDUCTIVITY
GAS
ENHANCEMENT
MECHANISM
Ключевые слова (''Своб.индексиров.''): d-wave superconductivity--electron density--electron spin polarisation--high-temperature superconductors--hubbard model--superconducting transition temperature--t-j model--two-dimensional electron gas
Аннотация: We demonstrate the possibility of triplet p-wave pairing at low electron density a large number of models such as 3D and 2D Fermi-gas models with hard-core repulsion, 3D and 2D Hubbard models, and the Shubin-Vonsovsky model. The critical temperature for p-wave pairing can be considerably higher in the spin-polarized case or even in a two-band situation at low density and can reach experimentally observable values of 1–5 K. We also discuss briefly the d-wave pairing and high-Tc superconductivity with Tc ∼ 100 K which arise in the extended Hubbard model and in the generalized t-Jmodel when close to half-filling.
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Volkov N. V., Sablina K. A., Bayukov O. A., Eremin E. V., Petrakovskii G. A., Velikanov D. A., Balaev A. D., Bovina A. F., Boni P., Clementyev E.
Заглавие : Magnetic properties of the mixed-valence manganese oxide Pb(3)Mn(7)O(15)
Разночтения заглавия :авие SCOPUS: Magnetic properties of the mixed-valence manganese oxide Pb 3Mn7O15
Место публикации : J. Phys.: Condens. Matter: IOP PUBLISHING LTD, 2008. - Vol. 20, Is. 5. - Ст.55217. - ISSN 0953-8984, DOI 10.1088/0953-8984/20/5/055217
Примечания : Cited References: 16
Предметные рубрики: CRYSTAL-STRUCTURE
PHASE-SEPARATION
Ключевые слова (''Своб.индексиров.''): crystal structure--magnetization--manganese compounds--phase interfaces--x ray diffraction--manganese oxide--space groups--temperature range--single crystals
Аннотация: A Pb(3)Mn(7)O(15) single crystal has been grown by the flux method and studied using x-ray diffraction and magnetization measurements. The crystal is hexagonal (P6(3)/mcm space group, Z = 4) and exhibits a pronounced layered nature. Along the [001] direction (c axis), the structure consists of layers of edge-sharing MnO(6) octahedra. Pairs of Mn atoms occupy the octahedral sites located between layers forming 'bridges' along the c axis, which link neighboring Mn layers. The magnetic properties of the crystal have been investigated using ac and dc magnetization measurements in the temperature range 2-900 K at magnetic fields up to 90 kOe. The experimental data obtained suggest that in the temperature region under study several different magnetic phases can be distinguished. Down to similar to 250 K, the crystal is in the paramagnetic state. Below this temperature, short-range antiferromagnetic ordering apparently starts forming within Mn layers, although a transition to long-range magnetic order occurs at 70 K. The magnetization data obtained leads us to conclude that this state is canted antiferromagnetic with moments lying in the basal plane of the crystal. In addition, below 20 K the crystal undergoes one more magnetic transition that corresponds to spin reorientation.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Romanova O. B., Aplesnin S. S., Sitnikov M. N., Udod L. V., Kharkov A. M.
Заглавие : Magnetoresistance and magnetoimpedance in holmium manganese sulfides
Коллективы : Russian Foundation for Fundamental InvestigationsRussian Foundation for Basic Research (RFBR) [20-42-243002]
Место публикации : Appl. Phys. A. - 2022. - Vol. 128, Is. 2. - Ст.124. - ISSN 0947-8396, DOI 10.1007/s00339-021-05198-x. - ISSN 1432-0630(eISSN)
Примечания : Cited References: 46. - Funding was provided by Russian Foundation for Fundamental Investigations (20-42-243002)
Предметные рубрики: PHASE-SEPARATION
IMPEDANCE
Аннотация: The structure, transport characteristics, real and imaginary parts of the impedance components and electric polarization of the HoXMn1-XS (X = 0.1 and 0.2) system have been investigated in the temperature range of 80-500 K in magnetic fields of up to 12 kOe. The morphology of synthesized samples has been studied. The influence of the magnetic field on the transport characteristics, on both direct and alternating currents of holmium manganese sulfides, have been established. The negative effects of DC magnetoresistance in the region of the magnetic phase transition and positive AC magnetoimpedance up to 4% in the paramagnetic region have been established. The critical temperatures of the existence of the electric polarization have been determined. At a substitution concentration of X = 0.1, the activation character of the relaxation time versus temperature has been found. The diffusion contribution for the composition with X = 0.2 has been established by the impedance hodograph.
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