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Wyszukujesz frazę "75.20.Hr" wg kryterium: Temat


Tytuł:
Magnetic Susceptibility of Cd$\text{}_{1-x}$Fe$\text{}_{x}$Te$\text{}_{1-y}$Se$\text{}_{y}$
Autorzy:
Arciszewska, M.
Mycielski, A.
Dobrowolski, W.
Lenard, A.
Mauger, A.
Witkowska, B.
Powiązania:
https://bibliotekanauki.pl/articles/1890693.pdf
Data publikacji:
1991-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.80.Ey
75.20.Hr
75.30.Cr
Opis:
Magnetic susceptibility of Cd$\text{}_{1-x}$Fe$\text{}_{x}$Te$\text{}_{1-y}$Se$\text{}_{y}$ was found to consist of Van Vleck term (characteristic for the Fe$\text{}^{2+}$ centers in tetrahedral crystal symmetry) and temperature-dependent contribution. The occurrence of the latter indicates an existence of additional magnetic moments. We ascribe their origin to the modification of the Fe$\text{}^{2+}$ energy level spectrum induced by mixed Te-Se anion environment.
Źródło:
Acta Physica Polonica A; 1991, 80, 2; 303-306
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Susceptibility Studies of Fe-Doped II-VI Compounds
Autorzy:
Arciszewska, M.
Powiązania:
https://bibliotekanauki.pl/articles/1886787.pdf
Data publikacji:
1991-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.Hr
72.80.Ey
75.30.Cr
Opis:
Low-field magnetic susceptibility χ of Fe-doped II-VI compounds has been studied for wide iron concentration range (3 x 10$\text{}^{18}$ ≤ N$\text{}_{Fe}$ ≤ 10$\text{}^{21}$ cm$\text{}^{-3}$). For the low iron content the Van Vleck-type paramagnetism is observed at low temperatures in all investigated materials (except for Hg$\text{}_{1-x}$Fe$\text{}_{x}$Se), which entirely confirms the theoretical prediction. For the higher Fe contents the experimental data still remain unexplained.
Źródło:
Acta Physica Polonica A; 1991, 79, 2-3; 341-344
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermodynamic and Magnetotransport Properties of High Quality $Na_{0.77}CoO_{2}$ Single Crystals
Autorzy:
Baran, A.
Zorkovská, A.
Kajňaková, M.
Lin, C.
Feher, A.
Powiązania:
https://bibliotekanauki.pl/articles/1371577.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.Hr
75.40.Cx
75.47.-m
Opis:
Heat capacity and electrical resistivity of high-quality $Na_{0.77}CoO_{2}$ single crystals was systematically studied as a function of temperature and magnetic field. Anomalies at 20 K have been observed both in the heat capacity and the electrical resistivity. The broad bump in the heat capacity indicates a smeared magnetic phase transition. Magnetic fields up to 9 T, oriented perpendicularly to the ab plane, reduce the temperature of this anomaly in accordance with the assumption of A-type antiferromagnetic ordering. The low temperature upturn observed in resistivity below 20 K for slow cooling is also suppressed by the magnetic field. This anomaly is probably the consequence of the interplay of several different mechanisms, including the Kondo effect, electron-electron interactions, and electron-phonon scattering.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 360-361
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On Magnetic Impurities in Gapless Fermi Systems
Autorzy:
Borkowski, L. S.
Powiązania:
https://bibliotekanauki.pl/articles/1955519.pdf
Data publikacji:
1997-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.15.Qm
75.20.Hr
74.70.Tx
Opis:
In ordinary metals, antiferromagnetic exchange between conduction electrons and a magnetic impurity leads to screening of the impurity spin below the Kondo temperature, T$\text{}_{K}$. In systems such as semimetals, small-gap semiconductors and unconventional superconductors, a reduction in available conduction states near the chemical potential can greatly depress T$\text{}_{K}$. The behavior of an Anderson impurity in a model with a power-law density of states, ρ(ε) ∝ |ε|$\text{}^{r}$, r>0, for |ε|<Δp, where Δp is small compared to the bandwidth, is studied using the non-crossing approximation. The transition from the Kondo singlet to the magnetic ground state can be seen in the behavior of the impurity magnetic susceptibility χ. The product Tχ saturates at a finite value at low temperature for coupling smaller than the critical one. For sufficiently large coupling Tχ → 0, as T → 0, indicating a complete screening of the impurity spin.
Źródło:
Acta Physica Polonica A; 1997, 91, 2; 359-362
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Interplay of Kondo and Fano Resonance in Electronic Transport in Nanostructures
Autorzy:
Bułka, B. R.
Stefański, P.
Tagliacozzo, A.
Powiązania:
https://bibliotekanauki.pl/articles/2043700.pdf
Data publikacji:
2005-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.63.-b
72.15.Qm
75.20.Hr
Opis:
Quantum interference and electronic correlations are processes relevant for electronic transport in nanostructures. We present theoretical studies of transport for various models, which take into account these processes and describe the Fano resonance as well as many-body effects like the Kondo resonance. The results are compared with transport measurements performed on a small quantum dot strongly coupled to electrodes, a large semi-open quantum dot, a side-attached quantum dot to a quantum wire systems and a quantum dot embedded in the metallic ring. We show how conductance characteristics of the Kondo and the Fano resonance are modified in different situations.
Źródło:
Acta Physica Polonica A; 2005, 108, 4; 555-569
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ferromagnetism and Metal-Insulator Transitions in Correlated Electron Systems with Alloy Disorder
Autorzy:
Byczuk, K.
Yu, U.
Hofstetter, W.
Vollhardt, D.
Powiązania:
https://bibliotekanauki.pl/articles/1810278.pdf
Data publikacji:
2009-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.23.-k
75.20.Hr
75.30.Mb
Opis:
Alloy disorder can affect ferromagnetism and metal-insulator transitions of correlated lattice fermion systems in subtle and often unexpected ways. Solving the Hubbard model and the periodic Anderson model within dynamical mean-field theory we show that alloy disorder can increase the Curie temperature of a non-disordered system, and also yields novel Mott or Kondo insulators at fractional electronic densities.
Źródło:
Acta Physica Polonica A; 2009, 115, 1; 7-12
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Kondo Lattice and Magnetic Properties in Strongly Correlated Electron Systems
Autorzy:
Coqblin, B.
Powiązania:
https://bibliotekanauki.pl/articles/1810279.pdf
Data publikacji:
2009-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.27.+a
72.15.Qm
75.10.Nr
75.20.Hr
Opis:
We review here the magnetic properties of some strongly correlated electron systems and especially cerium and uranium compounds. The normal Kondo lattice model with a localized S=1/2 spin can account for the Kondo-magnetism competition observed in cerium or ytterbium systems, while the underscreened Kondo lattice model with a localized S=1 spin can well account for the ferromagnetism - Kondo coexistence observed in some uranium compounds such as UTe. Then, we discuss the spin glass-Kondo competition and present the resulting phase diagrams showing spin glass, Kondo and magnetically ordered phases observed in disordered heavy fermion cerium alloys such as $CeNi_xCu_{1-x}$ alloys.
Źródło:
Acta Physica Polonica A; 2009, 115, 1; 13-17
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetism and Kondo Effect in Cerium and Uranium Compounds
Autorzy:
Coqblin, B.
Powiązania:
https://bibliotekanauki.pl/articles/1813756.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.Hr
75.30.Mb
05.50.+q
64.60.Cn
Opis:
A brief review of the Kondo lattice problem is presented, with a special emphasis on the underscreened Kondo effect in ferromagnetic-Kondo uranium compounds and on the spin glass-Kondo competition in disordered heavy fermion cerium alloys.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 391-394
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Kondo Lattice Models and Magnetism for Cerium and Uranium Systems
Autorzy:
Coqblin, B.
Powiązania:
https://bibliotekanauki.pl/articles/1534596.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Mb
75.20.Hr
05.50.+q
64.60.Cn
Opis:
The interplay between the Kondo effect and magnetism is important in anomalous rare-earth and actinide systems and a brief review of the different Kondo lattice models is presented here. The first studied case is the classical Kondo lattice model with S = 1/2 spins for the 4f localized electrons, which describes the strong competition between the Kondo effect and magnetic ordering leading to small ordering temperatures less than roughly 10 K. The second reviewed case describes the underscreened Kondo lattice model with S = 1 spins for the 5f localized electrons, which can account for the coexistence of both the Kondo effect and the ferromagnetic order and, therefore, the large Curie temperatures observed in actinide compounds like UTe and $NpNiSi_2$; the question of the delocalization of the 5f electrons is also discussed here. The last case describes the competition between the "spin glass" behaviour, the Kondo effect and the magnetic ordering in disordered cerium alloys like $CeNi_{x}Cu_{1 - x}$ or $CeRh_{x}Pd_{1 - x}$ and several models used for the spin glass state are reviewed, as well as the occurrence of magnetic glass clusters.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 913-918
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ab Initio Study of Electronic and Magnetic Structure and Structural Phase Transition of $(Fe_{1 - x}Mn_{x})_2P_{1 - y}Ge_{y}$ Alloys
Autorzy:
Deniszczyk, J.
Woźniakowski, A.
Kolano, R.
Kolano-Burian, A.
Powiązania:
https://bibliotekanauki.pl/articles/1427520.pdf
Data publikacji:
2012-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.Be
75.20.Hr
Opis:
The paper presents results of the ab initio electronic structure calculations performed for the $(Fe_{0.5}Mn_{0.5})_2P_{0.67}Ge_{0.33}$ alloy, a member of $(Fe_{1 - x}Mn_{x})_2P_{1 - y}Ge_{y}$ family of alloys showing a giant magnetocaloric effect. Calculations confirmed the strong relationship between the magnetic state and crystal structure of the alloy. To investigate the isostructural phase transition driven by external magnetic field observed in $(Fe_{0.9}Mn_{1.1})P_{0.8}Ge_{0.2}$ we utilized the fixed spin moment approach. Total energy analysis confirmed the occurrence of isostructural phase transition.
Źródło:
Acta Physica Polonica A; 2012, 121, 5-6; 1162-1164
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Mott Transition in Disordered Systems
Autorzy:
Dobrosavljević, V.
Kotliar, G.
Powiązania:
https://bibliotekanauki.pl/articles/1860793.pdf
Data publikacji:
1994-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.Hr
71.55.Jv
Opis:
We review the recent progress in understanding the Mott transition in disordered systems using the mean-field approach to the strong correlation problem. It is based on a new functional integral formulation of the disordered interacting electron problem. The saddle-point solution recovers a mean-field theory of the strong correlation problem, and becomes exact in the limit of large spatial coordination. We compare the results of the mean-field theory with experimental findings and indicate directions for future work.
Źródło:
Acta Physica Polonica A; 1994, 85, 1; 21-38
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Behaviour of the Ce-Co-Mn Intermetallics of MgCu₂ Structure Type
Autorzy:
Dudric, R.
Popescu, A.
Isnard, O.
Pop, V.
Coldea, M.
Powiązania:
https://bibliotekanauki.pl/articles/1402321.pdf
Data publikacji:
2015-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.Eh
75.20.En
75.20.Hr
75.30.Cr
Opis:
The magnetic properties of CeCoMn, Ce₃Co₃Mn₄ and Ce₃Co₆Mn alloys have been investigated by magnetization and susceptibility measurements in the temperature range (5-300) K and magnetic field up to 12 T. X-ray powder diffraction measurements showed that all three alloys are isostructural and crystallize in the cubic MgCu₂ structure type. Both Ce and Co atoms are non-magnetic in all alloys like in the isostructural compound CeCo₂. Magnetic behavior of the investigated alloys is mostly due to the Mn moments and depends essentially on the Mn-Mn distances. The interaction between the Mn moments is antiferromagnetic in CeCoMn and Ce₃Co₃Mn₄ but a paramagnetic behavior for Ce₃Co₆Mn was evidenced in the studied temperature range.
Źródło:
Acta Physica Polonica A; 2015, 128, 1; 67-71
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Is the Magnetism of HgSe:Fe Clearly Understood?
Autorzy:
Dybko, K.
Łusakowski, A.
Kossut, J.
Arciszewska, M.
vd Linden, P. J. E. M.
Wittlin, A.
Perenboom, J. A. A. J.
Mycielski, A.
Powiązania:
https://bibliotekanauki.pl/articles/1931952.pdf
Data publikacji:
1995-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Hx
75.20.Hr
Opis:
The high magnetic field magnetization measurements of low composition Hg$\text{}_{1-x}$Fe$\text{}_{x}$Se (0.0002 < x < 0.003) at temperatures ranging from 1.6 K to 40 K and in magnetic fields up to 20 T are reported. The magnetization in a sample containing only Fe$\text{}^{3+}$ ions (x = 0.0002) is described by the Brillouin function (j = 5/2). The magnetization in the sample codoped with Ga, containing only Fe$\text{}^{2+}$ is well described in the model of isolated Fe$\text{}^{2+}$ ions. The latter model takes into account the tetrahedral crystal field, the spin-orbit interaction and the Zeeman term. On the other hand, the magnetization of sample with both Fe$\text{}^{3+}$ and Fe$\text{}^{2+}$ present simultaneously (x = 0.003) is shown to be different from a simple additive superposition of the contributions due to Fe$\text{}^{3+}$ and Fe$\text{}^{2+}$ subsystems. The possible origin of this discrepancy is discussed.
Źródło:
Acta Physica Polonica A; 1995, 87, 1; 193-196
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Specific Heat of $YbNi_4Si$ Compound
Autorzy:
Falkowski, M.
Kowalczyk, A.
Toliński, T.
Powiązania:
https://bibliotekanauki.pl/articles/1813487.pdf
Data publikacji:
2008-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
82.80.Pv
65.40.Ba
75.20.Hr
Opis:
The specific heat of $YbNi_4Si$ has been analyzed considering the electronic contribution and the lattice contributions in frames of the Debye model. Based on the specific heat measurements, the electronic specific heat coefficient γ = 25 mJ $mol^{-1} K^{-2}$ and the Debye temperature $θ_D$ = 320 K were derived. This small value shows that $YbNi_4Si$ cannot be classified as a heavy fermion system. These studies are completed by magnetic susceptibility, X-ray photoemission spectroscopy, and electrical resistivity.
Źródło:
Acta Physica Polonica A; 2008, 113, 2; 641-644
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Susceptibility of HgTe⟨Mn,Fe,Cr⟩
Autorzy:
Frasunyak, V. M.
Gavaleshko, M. P.
Powiązania:
https://bibliotekanauki.pl/articles/1933741.pdf
Data publikacji:
1995-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.Hr
Opis:
The results of the investigations of magnetic susceptibility (χ) of HgTe⟨Mn,Fe,Cr⟩ with N$\text{}_{3d}$ < 10$\text{}^{21}$ cm$\text{}^{-3}$ in temperature range of 80-290 K and for magnetic fields of 0.4-9 kOe are presented. It was shown that χ$\text{}_{Mn}$(T) and χ$\text{}_{Fe}$(T) in HgTe⟨Mn,Fe⟩ are described by Curie law and for Ν$\text{}_{3d}$ > 10$\text{}^{21}$ cm$\text{}^{-3}$ - by Curie-Weiss law with negative value of θ$\text{}_{p}$, characterizing the antiferromagnetic interaction between magnetic ions. Thermal treatment of HgTe⟨Fe⟩ samples in Hg vapour at Τ = 500 K in contrast to HgTe⟨Mn⟩ leads to the redistribution of magnetic component only in these samples. A special behaviour of χ(T) in HgTe⟨Cr⟩ samples was revealed which is different from x(T) in HgTe⟨Mn,Fe⟩.
Źródło:
Acta Physica Polonica A; 1995, 88, 4; 715-718
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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