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392 results on '"Panfilov, A. S."'

58. Pressure effects on magnetic properties of LaMnO3 and YMnO3.

Author

Panfilov, A. S., Grechnev, G. E., Pashchenko, V. A., and Prabhakaran, D.

Subjects
*MAGNETIC properties, *CURIE temperature, *MAGNETIC susceptibility, *HYDROSTATIC pressure
Abstract

The magnetic susceptibility χ of RMnO3 (R = La, Y) manganites was measured for paramagnetic phase as a function of the hydrostatic pressure P up to 2 kbar at some fixed temperature in the range from 78 to 300 K. A pronounced magnitude of the pressure effect dln χ/dP was found to be positive in sign for LaMnO3 and negative for YMnO3, both being strongly temperature dependent. Analysis of the experimental data, based on the Curie-Weiss behavior of χ(Τ), allowed to estimate the pressure derivative of the paramagnetic Curie temperature to be dΘ/dP = (0.25 ± 0.03) and −(2.4 ± 0.4) K/kbar for LaMnO3 and YMnO3, respectively. [ABSTRACT FROM AUTHOR]

Published
2023
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59. Pressure effects on magnetic properties of LaMnO3 and YMnO3.

Author

Panfilov, A. S., Grechnev, G. E., Pashchenko, V. A., and Prabhakaran, D.

Subjects
MAGNETIC properties, CURIE temperature, MAGNETIC susceptibility, HYDROSTATIC pressure
Abstract

The magnetic susceptibility χ of RMnO3 (R = La, Y) manganites was measured for paramagnetic phase as a function of the hydrostatic pressure P up to 2 kbar at some fixed temperature in the range from 78 to 300 K. A pronounced magnitude of the pressure effect dln χ/dP was found to be positive in sign for LaMnO3 and negative for YMnO3, both being strongly temperature dependent. Analysis of the experimental data, based on the Curie-Weiss behavior of χ(Τ), allowed to estimate the pressure derivative of the paramagnetic Curie temperature to be dΘ/dP = (0.25 ± 0.03) and −(2.4 ± 0.4) K/kbar for LaMnO3 and YMnO3, respectively. [ABSTRACT FROM AUTHOR]

Published
2023
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64. Magnetic and structural properties of La1−xGdx CoO3 compounds

Author

Panfilov, Anatoly S., Grechnev, Gennadiy E., Lyogenkaya, Anastasiya A., Pashchenko, Volodymyr A., Vasylechko, Leonid O., Hreb, Vasyl M., and Kovalevsky, Andrei V.

Subjects
Magnetic susceptibility, Spin states crossover, Chemical pressure effect, La1−x Gdx CoO3 compounds
Abstract

We present a study of magnetic and structural properties of La1−xGdxCoO3 compounds with x = 0, 0.2, 0.5 and 1. The Gd term in magnetic susceptibility obeys the Curie-Weiss law with antiferromagnetic interaction between the magnetic moments of Gd3+ ions. The value of the paramagnetic Curie temperature Θ is proportional to Gd content and for GdCoO3 it reaches Θ ' −5.5 K. The Co contribution, χCo(T), derived by subtracting the Gd term from the total susceptibility, shows a non-monotonous behavior which is originated by the temperature induced transition of Co3+ ions from the ground low spin state to a higher spin state separated by an energy ∆. The revealed strong increase in ∆ with increasing Gd content is presumably due to the manifestation of a chemical pressure upon replacing La with Gd having a smaller ionic size. published

Published
2021

65. The Color of the Surface of Venus

Author

Pieters, C. M., Head, J. W., Patterson, W., Pratt, S., Garvin, J., Barsukov, V. L., Basilevsky, A. T., Khodakovsky, I. L., Selivanov, A. S., Panfilov, A. S., and Narayeva, Y. M.

Published
1986

90. Effects of temperature and pressure on the magnetic properties of La1–xPrxCoO3

Author

Panfilov, Anatoliy S., Lyogenkaya, Anastasiya A., Grechnev, Gennadiy E., Pashchenko, Volodymyr A., Vasylechko, Leonid O., Hreb, Vasyl M., and Kovalevsky, Andrei V.

Subjects
High-pressure effects, Spin crossovers, Electronic structure calculations, RCoO3 compounds, Magnetic measurements
Abstract

For La1–xPrxCoO3cobaltites (x¼0, 0.1, 0.2, and 0.3), the dependence ofmagnetic susceptibilityχðTÞis studied in the temperature range 5–400 K. Also,the crystal structure of these cobaltites is investigated, and the effect ofpressure up to 2 kbar on their susceptibility is measured atT¼78, 150, and300 K. The specificdependenciesχðTÞandthelargenegativepressureeffectare assumed to arise from Co3þions contribution to the total susceptibilityevaluated using La1 xPrxAlO3as a reference system. The obtained experi-mental data on temperature and pressure effects in magnetism are analyzedwithin a two-level model with energy gapΔbetween the ground state of thesystem with zero spin of Co3þions and the excited higher-spin state. In thismodel, magnetism of Co3þions is determined by the temperature-inducedpopulation of the excited state, and magnitude of the pressure effect is gov-erned by the volume dependence ofΔ. The results of the analysis, supple-mented by the theoretical calculations of the electronic structures of LaCoO3and PrCoO3, indicate significant increase inΔwith decrease in the unit cellvolume both under hydrostatic pressure and by substituting La with Pr having asmaller ionic radius. published

Published
2020

94. Pressure effect on magnetic susceptibility of intermediate-valence compound YbInAu2.

Author

Panfilov, A. S. and Grechnev, G. E.

Subjects
*MAGNETIC susceptibility, *KONDO effect, *ANDERSON model, *FERMI energy, *FERMI level, *COULOMB functions
Abstract

The pressure dependence of the magnetic susceptibility of the intermediate-valence compound YbInAu2 has been measured in the temperature range of 78−300 K, showing a strong and temperature-dependent increase in susceptibility under pressure. The initial analysis of the experimental data within the framework of the integer valence Coqblin–Schrieffer model has given certain estimates of the Kondo temperature and its pressure derivative, but did not allow to describe quantitatively the specific temperature dependence of the susceptibility itself. The Anderson impurity model with infinite Coulomb repulsion U, the main parameters of which are the position of the f level relative to the Fermi energy and its hybridization width, turned out to be more suitable to describe the obtained experimental data for YbInAu2, indicating a strong dependence of the f-level position on the atomic volume. [ABSTRACT FROM AUTHOR]

Published
2022
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95. Pressure effect on magnetic susceptibility of intermediate-valence compound YbInAu2.

Author

Panfilov, A. S. and Grechnev, G. E.

Subjects
MAGNETIC susceptibility, KONDO effect, ANDERSON model, FERMI energy, FERMI level, COULOMB functions
Abstract

The pressure dependence of the magnetic susceptibility of the intermediate-valence compound YbInAu2 has been measured in the temperature range of 78−300 K, showing a strong and temperature-dependent increase in susceptibility under pressure. The initial analysis of the experimental data within the framework of the integer valence Coqblin–Schrieffer model has given certain estimates of the Kondo temperature and its pressure derivative, but did not allow to describe quantitatively the specific temperature dependence of the susceptibility itself. The Anderson impurity model with infinite Coulomb repulsion U, the main parameters of which are the position of the f level relative to the Fermi energy and its hybridization width, turned out to be more suitable to describe the obtained experimental data for YbInAu2, indicating a strong dependence of the f-level position on the atomic volume. [ABSTRACT FROM AUTHOR]

Published
2022
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