Search

Your search keyword '"Savenko, B.N."' showing total 91 results
Start Over Author "Savenko, B.N." Language english
91 results on '"Savenko, B.N."'

28. INVESTIGATION OF CRYSTAL AND MAGNETIC STRUCTURE OF SPINEL FERRITES UNDER HIGH PRESSURE

Author

Belozerova, N.M., Kichanov, S.E., Kozlenko, D.P., Lukin, E.V., and Savenko, B.N.

Subjects
Condensed Matter::Materials Science, Condensed Matter::Strongly Correlated Electrons, Condensed Matter::Disordered Systems and Neural Networks
Abstract

A study of spinel ferrites is great importance regarding their interesting structural and magnetic properties having both fundamental and applied interest [1]. In particular, the canted antiferromagnetic, ferrimagnetic, spin glass and semi-spin glass states can be realized in these compounds [2].

Published
2021
Full Text
View/download PDF

37. Pressure effect on magnetic susceptibility of LaCoO₃

Author

Panfilov, A.S., Grechnev, G.E., Zhuravleva, I.P., Lyogenkaya, A.A., Pashchenko, V.A., Savenko, B.N., Novoselov, D., Prabhakaran, D., and Troyanchuk, I.O.

Subjects
Низкотемпеpатуpный магнетизм
Abstract

The effect of pressure on magnetic properties of LaCoO₃ is studied experimentally and theoretically. The pressure dependence of magnetic susceptibility χ of LaCoO₃ is obtained by precise measurements of χ as a function of the hydrostatic pressure P up to 2 kbar in the temperature range from 78 K to 300 K. A pronounced magnitude of the pressure effect is found to be negative in sign and strongly temperature dependent. The obtained experimental data are analysed by using a two-level model and DFT+U calculations of the electronic structure of LaCoO₃ . In particular, the fixed spin moment method was employed to obtain a volume dependence of the total energy difference Δ between the low spin and the intermediate spin states of LaCoO₃ . Analysis of the obtained experimental χ(P) dependence within the two-level model, as well as our DFT+U calculations, have revealed the anomalous large decrease in the energy difference Δ with increasing of the unit cell volume. This effect, taking into account a thermal expansion, can be responsible for the temperatures dependence of Δ, predicting its vanishing near room temperature.

Published
2018

43. Structure and magnetic properties of YCo5 compound at high pressures.

Author

Burzo, E., Vlaic, P., Kozlenko, D.P., Golosova, N.O., Kichanov, S.E., Savenko, B.N., Ostlin, A., and Chioncel, L.

Subjects
MAGNETIC structure, MAGNETIC properties, ELECTRON-electron interactions, LATTICE constants, NEUTRON diffraction
Abstract

The crystal structure and magnetic properties of YCo 5 compound have been studied by neutron diffraction, in the pressure range 0 ≤ p ≤ 7.2 GPa. The cobalt moments decrease with pressure, parallelly with anisotropic changes of lattice parameters. The experimental data are analyzed together with results from the combined Density Functional and Dynamical Mean-Field Theory. A rather good agreement between the experimentally determined and calculated values of cobalt moments is shown. Our scenario for the behavior of YCo 5 under pressure, is the combined action of the Lifshitz transition with a strong local electron-electron interaction. [ABSTRACT FROM AUTHOR]

Published
2020
Full Text
View/download PDF

46. Crystal structure, magnetic properties and conductivity mechanisms of La 0.7 Ca 0.3 Mn 0.5 Fe 0.5 O 3.

Author

Dang, N.T., Zakhvalinskii, V.S., Kozlenko, D.P., Nekrasova, Yu.S., Phan, The-Long, Thang, Ta Thu, Kichanov, S.E., Thanh, T. D., Savenko, B.N., Khiem, L.H., Taran, S.V., and Jabarov, S.G.

Subjects
IRON oxides, CRYSTAL structure, CERAMIC materials, X-ray diffraction, NEUTRON diffraction, SUBSTITUTION reactions
Abstract

La0.7Ca0.3Mn0.5Fe0.5O3(LCMFO) ceramic samples were prepared by conventional solid-state reaction. X-Ray diffraction investigations show that samples have orthorhombic space group Pnma (a = 5.447(2) Ǻ, b = 7.709(3) Ǻ, c = 5.467(3) Ǻ). During the neutron powder diffraction measurements of LCMFO in the temperature range of 10 ÷ 300 K the antiferromagnetic long-range ordering of G-type was seen. It has been established that 50% substitution of Mn/Fe leads to a complete suppression of the ferromagnetism in LCMFO samples. Investigations of temperature dependence of the magnetization, M(T), suggests the frustration of magnetic ground state and the existence of a spin-glass or a cluster-glass phase below the magnetic transition temperature close to 350 K. The temperature dependences of conductivity for La0.7Ca0.3Mn0.5Fe0.5O3sample investigated in magnetic fields B = 0 and 1 T. According to the research, the mechanisms of hopping conductivity were established. Micro parameters in density of localized states were calculated for LCMFO samples. The width of the Coulomb gap Δ = 0.67 eV, rigid gap δ = 0.324 eV and the localization radii of charge carriers were estimated. [ABSTRACT FROM PUBLISHER]

Published
2016
Full Text
View/download PDF

47. Spin fluctuations and structural modifications in frustrated multiferroics RMnO3 (R=Y, Lu) at high pressure.

Author

Kozlenko, D.P., Kichanov, S.E., Lukin, E.V., Lee, S., Park, J.-G., and Savenko, B.N.

Subjects
MANGANITE, MANGANESE ores, HIGH pressure (Science), ANTIFERROMAGNETISM, MAGNETIC properties, NEUTRON diffraction, PHASE transitions
Abstract

The crystal and magnetic structures of hexagonal manganites YMnO3 and LuMnO3 have been studied by powder neutron diffraction up to 6 GPa in the temperature range of 10-300 K. At ambient pressure, a triangular antiferromagnetic (AFM) state of a Γ1 irreducible representation is stable below TN=70 K in YMnO3. Upon application of high pressure, a spin-reorientation was observed and the triangular AFM structure evolves from Γ1 to Γ1+Γ2 representation symmetry. In LuMnO3, the triangular AFM state of a Γ2 symmetry with TN ≈ 95 K remains stable in the investigated pressure range. The ordered Mn magnetic moment is suppressed at high pressure and low temperature, with much more pronounced effects for YMnO3, indicating enhanced spin fluctuations due to stronger magnetic frustration of the triangular lattice under higher pressure. The relationship between the evolution of spin fluctuations and in-plane Mn-O bonds under pressure is analyzed. [ABSTRACT FROM AUTHOR]

Published
2010
Full Text
View/download PDF

48. Oxygen-deficiency and high-pressure effects on the magnetic and crystal structures of La0.7Sr0.3MnO3− d managanites.

Author

Kozlenko, D.P., Trukhanov, S.V., Lukin, E.V., Troyanchuk, I.O., Savenko, B.N., and Glazkov, V.P.

Subjects
MANGANITE, LANTHANUM compounds, CRYSTALS, OXYGEN, HIGH pressure (Science), SPIN glasses
Abstract

The magnetic and crystal structures of anion-deficient La0.7Sr0.3MnO3− d manganites ( d = 0.15 and 0.20) are studied by neutron diffraction in the range of high pressures 0–5 GPa and temperatures 10–300 K. It is found that a spin-glass state forms in La0.7Sr0.3MnO2.85 below T g ∼ 50 K, while magnetic phase separation is observed in La0.7Sr0.3MnO2.80, which is characterized by the coexistence of AFM domains of the C type with spin-glass domains. As distinct from the stoichiometric A0.5Ba0.5MnO3 manganites (A = Nd, Sm), in which the high-pressure effect suppresses the spin-glass state and gives rise to ferromagnetism, the spin-glass state in La0.7Sr0.3MnO2.85 is stable under pressure. The bulk modulus of La0.7Sr0.3MnO2.85 is considerably smaller than that for the stoichiometric La0.7Sr0.3MnO3 compound. The causes of the formation of different types of the magnetic structure in La0.7Sr0.3MnO3− d ( d = 0.15 and 0.20) and different high-pressure effects on the magnetic structure of stoichiometric and anion-deficient manganites are analyzed. [ABSTRACT FROM AUTHOR]

Published
2007
Full Text
View/download PDF

49. STRUCTURAL STUDY OF PRESSURE-INDUCED MAGNETIC PHASE TRANSITIONS IN MANGANITES Pr 0.7 Ca 0.3 Mn 1- y Fe y O 3 ( y  = 0, 0.1).

Author

Kozlenko, D.P., Glazkov, V.P., Medvedeva, I.V., Savenko, B.N., and Voronin, V.I.

Subjects
MANGANITE, NEUTRON diffraction, HIGH pressure (Science)
Abstract

A crystal and magnetic structure of manganites Pr 0.7 Ca 0.3 Mn 1- y Fe y O 3 ( y  = 0, 0.1) has been studied by means of powder neutron diffraction at pressures up to 4 GPa in the temperature range 15-300 K. Under high pressure, an appearance of A-type antiferromagnetic state in both systems was observed. Both compounds exhibit anisotropic compression of the lattice which leads to the apical compression of MnO 6 octahedra along the crystallographic b -axis. The calculated from obtained structural data pressure dependence of the charge-carrier bandwidth is in a qualitative agreement with observed pressure behavior of insulator-metal transition temperature within the framework of the double-exchange model. [ABSTRACT FROM AUTHOR]

Published
2003
Full Text
View/download PDF

50. INS study of vibrational spectra of NH[sub 4] I at very high pressures.

Author

Savenko, B.N., Glazkov, V.P., Kozlenko, D.P., Somenkov, V.A., and Telepnev, A.S.

Subjects
VIBRATIONAL spectra, NEUTRON scattering
Abstract

Vibrational spectra of NH[sub 4]I have been studied by means of incoherent inelastic neutron scattering at pressures up to 10 GPa using a high-pressure cell of the "toroid" type with tungsten carbide anvils. Librational (L) and transverse optical (TO) mode frequencies as a function of pressure were obtained. The observed behavior of these modes may be explained in terms of their hybridization at pressures P > 6 GPa. A change of dynamics of NH[sub 4]I due to this effect is a possible mechanism for the phase transition which occurs in this system at high pressure. [ABSTRACT FROM AUTHOR]

Published
2002
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results