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Пошуковий запит: (<.>AT=Panfilov Pressure effect on magnetic$<.>) |
Загальна кількість знайдених документів : 2
Представлено документи з 1 до 2
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| 1. |
Panfilov A. S.
Pressure effect on magnetic properties of gadolinium in paramagnetic state [Електронний ресурс] / A. S. Panfilov, G. E. Grechnev, A. V. Logosha, I. P. Zhuravleva // Физика и техника высоких давлений. - 2013. - Т. 23, № 1. - С. 5-12. - Режим доступу: http://nbuv.gov.ua/UJRN/PhTVD_2013_23_1_2
Проведены измерения парамагнитной восприимчивости Gd в интервале температур 295 - 365 К в условиях гидростатического сжатия до 0,16 ГПа, что позволило получить значения парамагнитной температуры Кюри <$ETHETA> и ее производной по давлению. Основываясь на результатах расчетов электронной структуры с использованием теории функционала плотности, исследовано поведение <$ETHETA> под давлением в рамках теории среднего поля. С этой целью были вычислены эффективная восприимчивость зонных d-электронов и соответствующие обменные интегралы как функции параметров решетки.The effect of pressure on magnetic properties of LaCoO3 is studied experimentally and theoretically. The pressure dependence of magnetic susceptibility <$E chi> of LaCoO3 is obtained by precise measurements of <$Echi> as a function of the hydrostatic pressure P up to 2 kBar in the temperature range from 78 K to 300 K. A pronounced magnitude of the pressure effect is found to be negative in sign and strongly temperature dependent. The obtained experimental data are analysed by using a two-level model and DFT + U calculations of the electronic structure of LaCoO3. In particular, the fixed spin moment method was employed to obtain a volume dependence of the total energy difference <$EDELTA> between the low spin and the intermediate spin states of LaCoO3. Analysis of the obtained experimental <$Echi (P)> dependence within the two-level model, as well as our DFT + U calculations, have revealed the anomalous large decrease in the energy difference <$EDELTA> with increasing of the unit cell volume. the temperatures dependence of <$EDELTA>, predicting its vanishing near room temperature.The pressure dependence of the magnetic susceptibility of the intermediate-valence compound YbInAu2 has been measured in the temperature range of 78 - 300 K, showing a strong and temperature-dependent increase in susceptibility under pressure. The initial analysis of the experimental data within the framework of the integer valence Coqblin - Schrieffer model has given certain estimates of the Kondo temperature and its pressure derivative, but did not allow to describe quantitatively the specific temperature dependence of the susceptibility itself. The Anderson impurity model with infinite Coulomb repulsion U, the main parameters of which are the position of the f level relative to the Fermi energy and its hybridization width, turned out to be more suitable to describe the obtained experimental data for YbInAu2, indicating a strong dependence of the f-level position on the atomic volume.
| | 2. |
Panfilov A. S.
Pressure effect on magnetic susceptibility of LaCoO3 [Електронний ресурс] / A. S. Panfilov, G. E. Grechnev, I. P. Zhuravleva, A. A. Lyogenkaya, V. A. Pashchenko, B. N. Savenko, D. Novoselov, D. Prabhakaran, I. O. Troyanchuk // Физика низких температур. - 2018. - Т. 44, № 4. - С. 432-438. - Режим доступу: http://nbuv.gov.ua/UJRN/PhNT_2018_44_4_12
Проведены измерения парамагнитной восприимчивости Gd в интервале температур 295 - 365 К в условиях гидростатического сжатия до 0,16 ГПа, что позволило получить значения парамагнитной температуры Кюри <$ETHETA> и ее производной по давлению. Основываясь на результатах расчетов электронной структуры с использованием теории функционала плотности, исследовано поведение <$ETHETA> под давлением в рамках теории среднего поля. С этой целью были вычислены эффективная восприимчивость зонных d-электронов и соответствующие обменные интегралы как функции параметров решетки.The effect of pressure on magnetic properties of LaCoO3 is studied experimentally and theoretically. The pressure dependence of magnetic susceptibility <$E chi> of LaCoO3 is obtained by precise measurements of <$Echi> as a function of the hydrostatic pressure P up to 2 kBar in the temperature range from 78 K to 300 K. A pronounced magnitude of the pressure effect is found to be negative in sign and strongly temperature dependent. The obtained experimental data are analysed by using a two-level model and DFT + U calculations of the electronic structure of LaCoO3. In particular, the fixed spin moment method was employed to obtain a volume dependence of the total energy difference <$EDELTA> between the low spin and the intermediate spin states of LaCoO3. Analysis of the obtained experimental <$Echi (P)> dependence within the two-level model, as well as our DFT + U calculations, have revealed the anomalous large decrease in the energy difference <$EDELTA> with increasing of the unit cell volume. the temperatures dependence of <$EDELTA>, predicting its vanishing near room temperature.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.
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