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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:
Anisotropy of Magnetic Interactions in HgFeSe
Autorzy:
Wilamowski, Z.
Przybylińska, H.
Joss, W.
Guillot, M.
Powiązania:
https://bibliotekanauki.pl/articles/1921599.pdf
Data publikacji:
1992-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.80.Ey
75.20.Hr
Opis:
Magnetic properties (susceptibility, high-field torque and magnetization) of cubic HgFeSe are analyzed. Van Vleck magnetism of Fe$\text{}^{2+}$ is well evidenced. The energy splitting of the Fe levels in HgSe is shown to differ considerably from that in other II-VI compounds.
Źródło:
Acta Physica Polonica A; 1992, 82, 4; 689-692
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Aspects of Magnetism in Heavy-Electron Metals
Autorzy:
Ott, H. R.
Powiązania:
https://bibliotekanauki.pl/articles/1860764.pdf
Data publikacji:
1994-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.-g
75.20.Hr
75.30.-m
75.30.Mb
Opis:
For some time it was believed that heavy-mass electrons at low temperatures, in special rare-earth and actinide compounds, were due to a particular suppression of magnetic order in these materials. Various experiments reveal, however, that magnetic order may occur from a heavy-electron state and that also a heavy-electron state may develop in the presence of a magnetically-ordered matrix. Even in materials with no sign of a cooperative phase transition, microscopic experimental probes give evidence for strong magnetic correlations, involving only very tiny (< 10^{-1} μ_{B}) ordered moments, however. All these experimental observations indicate that the heavy-electron state cannot always be regarded as a simple Fermi liquid in the usual sense. Various interactions of similar strength need to be considered. It is suggested that the balance of these interactions may lead to electronic inhomogeneities in k space. Both in magnetically-ordered or superconducting systems, unexpected electronic degrees of freedom appear to exist. In other cases experimental observations suggest magnetic inhomogeneities in real space which are not simply due to chemical inhomogeneities. Different examples of these various possibilities are demonstrated and discussed.
Źródło:
Acta Physica Polonica A; 1994, 85, 1; 7-19
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:
Cr-Based II-VI Semimagnetic Semiconductors
Autorzy:
Twardowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/1931875.pdf
Data publikacji:
1995-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Dg
75.30.Gw
75.50.Pp
75.20.Hr
78.30.Fs
Opis:
We review the magnetic and optical properties of recently grown Cr-based II-VI semimagnetic semiconductors. We focus on two features of these materials which distinguish them from other semimagnetic semiconductors: the particular magnetic behaviour of these crystals, resulting from the Cr$\text{}^{++}$ ion energy structure determined by a strong, static Jahn-Teller effect, and a ferromagnetic p-d exchange interaction, which is unique for II-VI semimagnetic semiconductors.
Źródło:
Acta Physica Polonica A; 1995, 87, 1; 85-93
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Bound Magnetic Polarons on Magnetic and Electrical Properties in Metallic n-Cd$\text{}_{0.95}$Mn$\text{}_{0.05}$Se
Autorzy:
Głód, P.
Sawicki, M.
Dietl, T.
Skośkiewicz, T.
Lenard, A.
Plesiewicz, W.
Powiązania:
https://bibliotekanauki.pl/articles/1931936.pdf
Data publikacji:
1995-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.30.+h
71.38.+i
75.20.Hr
Opis:
Doping-induced contribution to the millikelvin magnetic susceptibility of Cd$\text{}_{0.95}$Mn$\text{}_{0.05}$Se:In has been found to undergo a maximum at n ≈ 2n$\text{}_{c}$, and to vanish for n ≥ 8n$\text{}_{c}$, where n$\text{}_{c}$ is the electron concentration corresponding to the metal-insulator transition. This confirms the presence, also in the metallic phase, of bound magnetic polarons. Their slow dynamics may account for hysteresis visible in our magnetoresistance data.
Źródło:
Acta Physica Polonica A; 1995, 87, 1; 173-175
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:
Jahn-Teller Center as Quasiparticle of Fractional Statistics
Autorzy:
Sobolewski, A. I.
Powiązania:
https://bibliotekanauki.pl/articles/1933566.pdf
Data publikacji:
1995-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.Hr
31.10.+z
Opis:
Arguments are presented towards the identification of a molecular center undergoing a linear E⊗e Jahn-Teller effect as a quasiparticle of fractional statistics. The relevance of Jahn-Teller quasiparticles for the description of the type-II superconductivity is briefly discussed.
Źródło:
Acta Physica Polonica A; 1995, 88, 2; 305-313
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
Tytuł:
Magnetization of Pb$\text{}_{1-x}$Cr$\text{}_{x}$Te Semimagnetic Semiconductor
Autorzy:
Mac, W.
Story, T.
Twardowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/1876309.pdf
Data publikacji:
1995-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
75.20.Hr
Opis:
We present experimental studies of magnetization of Pb$\text{}_{1-x}$Cr$\text{}_{x}$Te (x ≤ 0.01) crystals. The reasonable description of the data is obtained for a composition of x ≤ 0.001 using Cr$\text{}^{+++}$ model (Brillouin type paramagnetism S = 3/2).
Źródło:
Acta Physica Polonica A; 1995, 87, 2; 492-494
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Anisotropy of Susceptibility and Optical investigation of the Antiferromagnetic phase Transition in U$\text{}_{1-x}$Ce$\text{}_{x}$Ru$\text{}_{2}$Si$\text{}_{2}$
Autorzy:
Mihalik, M.
Maťaš, S.
Macko, D.
Timko, M.
Menovsky, A. A.
Powiązania:
https://bibliotekanauki.pl/articles/1955512.pdf
Data publikacji:
1997-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Hb
75.20.Hr
72.15.-v
Opis:
Temperature dependence of magnetic susceptibility of U$\text{}_{1-x}$Ce$\text{}_{x}$Ru $\text{}_{2}$Si$\text{}_{2}$ single crystals (x=0, 0.025, 0.05, 0.075) has been studied at temperatures from 4.2 K up to room temperature and in magnetic fields applied along and perpendicular to the c-axis. The attention was paid to anomalies connected with the antiferromagnetic phase transition, which are present in crystals with x≤0.05. Far-infrared measurements of U$\text{}_{0.99}$Ce$\text{}_{0.01}$ Ru$\text{}_{2}$Si$\text{}_{2}$ single crystal have been studied for the first time. The measurements support the assumption that the origin of magnetic ordering in U$\text{}_{0.99}$Ce$\text{}_{0.01}$Ru$\text{}_{2}$Si$\text{}_{2}$ is the same as in heavy-fermion superconductor URu$\text{}_{2}$Si$\text{}_{2}$ and can be interpreted as being due to a spin-density-wave gap.
Źródło:
Acta Physica Polonica A; 1997, 91, 2; 351-354
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Behaviour in CeNiGa$\text{}_{2}$ and Ce$\text{}_{2}$Ni$\text{}_{2}$Ga
Autorzy:
Kaczorowski, D.
Rogl, P.
Powiązania:
https://bibliotekanauki.pl/articles/1964573.pdf
Data publikacji:
1997-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.Hr
75.30.Mb
Opis:
The bulk properties of CeNiGa$\text{}_{2}$ and Ce$\text{}_{2}$Νi$\text{}_{2}$Ga were studied by means of magnetic susceptibility, magnetization and electrical resistivity measurements. It was found that CeNiGa$\text{}_{2}$ is an antiferromagnetically ordered dense Kondo system whereas Ce$\text{}_{2}$Ni$\text{}_{2}$Ga exhibits a fluctuating valence behaviour.
Źródło:
Acta Physica Polonica A; 1997, 92, 2; 289-293
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Metals and Semimetals with Strongly Correlated Electrons
Autorzy:
Fulde, P.
Powiązania:
https://bibliotekanauki.pl/articles/1953157.pdf
Data publikacji:
1997-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.Hr
71.27.+a
71.10.Fd
75.30.Mb
Opis:
A characteristic feature of strongly correlated electrons is the appearance of low energy scales. They may result in heavy-quasiparticle excitations at low temperatures. Our understanding of these excitations has been considerably modified over the last few years. While it was originally thought that the Kondo effect is the sole source of heavy-fermion behavior, two additional mechanisms have been identified meanwhile. One is based on the Zeeman effect and occurs in Nd$\text{}_{2-x}$Ce$\text{}_{x}$CuO$\text{}_{4}$. The other is operative in the semimetal Yb$\text{}_{4}$As$\text{}_{3}$ and is based on nearly half filled one-dimensional Hubbard chains. In all three cases the low energy excitations result from spin degrees of freedom.
Źródło:
Acta Physica Polonica A; 1997, 91, 1; 67-76
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

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