Informacja

Drogi użytkowniku, aplikacja do prawidłowego działania wymaga obsługi JavaScript. Proszę włącz obsługę JavaScript w Twojej przeglądarce.

English (EN)·Polski (PL)·Yкраїнський (UK)
Przejdź do strony domowej biblioteki Centralna Biblioteka Wojskowa Link otwiera się w nowym oknie Logo biblioteki Prolib Integro - strona głównaCentralna Biblioteka Wojskowa

Wyszukujesz frazę "71:72" wg kryterium: Temat

  Lista filtrów
Wyrównaj
Wyświetlanie 1-15 z 25
Tytuł:
Electrical Conductivity for the Strongly Correlated and Hybridized Hubbard Band
Autorzy:
Kosimow, R.
Borgieł, W.
Deniszczyk, J.
Powiązania:
https://bibliotekanauki.pl/articles/2013654.pdf
Data publikacji:
2000-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.10.Fd
71.27.+a
72.10.-d
72.15.-v
Opis:
The magnetic and electrical transport properties of strongly correlated Hubbard band (f-band) hybridizing with the non-correlated conduction band (c-band) was studied. The many-body model Hamiltonian was treated within the modified alloy analogy scheme and the resulting one-body problem was solved with the use of coherent potential approximation. Within the Kubo-Greenwood formalism the dc electrical conductivity for bcc magnetic system was calculated and its variation with temperature and number of electrons was examined for different values of the Coulomb and hybridization (V) coupling constants. We found that the effect of strong correlations and hybridization on the conductivity is similar to that produced by the scattering due to the s-f interaction (spin disorder resistivity).
Źródło:
Acta Physica Polonica A; 2000, 97, 5; 799-802
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stabilization of Kondo Semiconductor State by Sb Doping of $CeNi_{1-δ}Sn_{1+δ}$ and the General Criterion of Its Appearance
Autorzy:
Spałek, J.
Ślebarski, A.
Powiązania:
https://bibliotekanauki.pl/articles/1812262.pdf
Data publikacji:
2008-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.27.+a
72.15.Qm
71.30.+h
Opis:
Semimetallic off-stoichiometric $CeNi_{1-δ}Sn_{1+δ-x}Sb_x$ system with δ≈0.06 is shown to transform into a Kondo semiconductor upon the substitution of few percent of Sb for Sn. The full-gap formation is associated with f-electron localization induced by the combined effect of the collective Kondo-singlet formation and the atomic disorder. Namely, the extra valence electrons introduced with the Sb doping (one per Sb atom) contribute additionally to the formation of the collective Kondo spin-singlet state at low temperatures, as seen by a substantial reduction of the magnetic susceptibility. The precise general definition of the Kondo semiconductor is provided and the difference with either the simple band or the Mott-Hubbard insulators is stressed.
Źródło:
Acta Physica Polonica A; 2008, 114, 1; 7-14
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin Polarons in Weakly Doped Antiferromagnets: Experimental Evidence Obtained for Cuprates
Autorzy:
Wróbel, P.
Suleja, W.
Eder, R.
Powiązania:
https://bibliotekanauki.pl/articles/1812270.pdf
Data publikacji:
2008-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.27.+a
71.10.Fd
74.72.-h
Opis:
The mechanism of spin polaron formation in moderately doped cuprates is discussed. These objects represent holes embedded into heavy clouds formed by spin fluctuations. Wave functions of spin polarons are spatially confined due to the increase in the exchange energy which is induced by hole motion giving rise to the creation of spin fluctuations. These wave functions are eigenstates of an "unperturbed" Hamiltonian which is defined by processes responsible for the tendency toward confinement. The eigenstates transform according to different irreducible representations of the point group reflecting the symmetry of the problem. Thus, the spin polarons being local wave functions resemble orbital states. The spectrum of optical conductivity in the mid-infrared range is determined by transitions between s-wave and p-wave spin polarons. The hybridization between different spin polarons which is induced by some high order processes gives rise to the formation of energy bands. The pronounced transfer of the spectral weight between different bands is induced by the coupling between spin fluctuations created by the hopping hole and local quantum fluctuations in the empty antiferromagnetic background from which an electron has been rejected, for example during the photoemission process. The form of the energy dispersion for spin polarons gives rise to the formation of a small Fermi surface at the low hole-doping range. These three above mentioned phenomena were observed in cuprates which seems to confirm the spin polaron scenario. The discussion of related experiments is the additional objective of this paper.
Źródło:
Acta Physica Polonica A; 2008, 114, 1; 51-58
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Charge Transport and Magnetism in $Tm_{0.03}Yb_{0.97}B_{12}$
Autorzy:
Glushkov, V.
Azarevich, A.
Anisimov, M.
Bogach, A.
Demishev, S.
Dukhnenko, A.
Filipov, V.
Flachbart, K.
Gabáni, S.
Gavrilkin, S.
Kondrin, M.
Shitsevalova, N.
Sluchanko, N.
Powiązania:
https://bibliotekanauki.pl/articles/1398286.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.15.Gd
72.15.Jf
71.27.+a
Opis:
Transport and magnetic properties of polycrystalline $Tm_{0.03}Yb_{0.97}B_{12}$ samples were investigated at temperatures 1.8-300 K in magnetic fields up to 9 T. The activated behavior of resistivity, the Hall coefficient and thermopower is described in terms of a narrow gap $ε_g$ ≈ 16.6 meV, which controls the charge transport in $Tm_{0.03}Yb_{0.97}B_{12}$ at T>40 K. The maximum of magnetic susceptibility found at 50 K is shown to be induced by a spin gap Δ ≈ 4.7 meV being close to the half of the spin fluctuation energy in YbB₁₂. Large diffusive thermopower S=AT, A=-29.1 μV/K² and the Pauli susceptibility χ₀ ≈ 7.2×10¯³ emu/mol found below 20 K seem to be associated with the many-body resonance, which corresponds to states with an enhanced effective mass m* ≈ 250m₀ (m₀ - free electron mass). The effective parameters of magnetic centers and the analysis of anomalies favor the nonequivalent states of substitute Tm ions.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 985-987
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
t-J Model Then and Now: a Personal Perspective from the Pioneering Times
Autorzy:
Spałek, J.
Powiązania:
https://bibliotekanauki.pl/articles/2047299.pdf
Data publikacji:
2007-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.27.+a
74.72.-h
71.10.Fd
Opis:
In this overview we sketch briefly the path to the so-called t-J model derived for the first time 30 years ago and provide its original meaning within the theory of strongly correlated magnetic metals with a non-Fermi (non-Landau) liquid ground state. An emergence of the concept of real space pairing is discussed in a historical prospective. A generalization of this model to the many-orbital situation is briefly discussed. The emphasis is put on didactical exposition of ideas, as they were transformed into mathematical language. The concept of hybrid pairing is introduced in the same context at the end.
Źródło:
Acta Physica Polonica A; 2007, 111, 4; 409-424
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Kondo Insulating State in CeRhSb$\text{}_{1-x}$Sn$\text{}_{x}$ as a Function of Carrier Number and Its Subsequent Metallization
Autorzy:
Ślebarski, A.
Spałek, J.
Powiązania:
https://bibliotekanauki.pl/articles/2047307.pdf
Data publikacji:
2007-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.27.+a
72.15.Qm
71.30.+h
Opis:
A quantum critical point represents an essential singularity in the phase diagram of the electron-correlated compounds. In the CeRhSb$\text{}_{1-x}$Sn$\text{}_{x}$ system we have observed a quantum criticality at the boundary Kondo insulator-non-Fermi liquid state. In this series of compounds, CeRhSb has a Kondo insulating ground state, whereas CeRhSn exhibits a non-Landau Fermi liquid behavior. In view of different types of behavior of CeRhSb and CeRhSn, we review the results of the solution in CeRhSb$\text{}_{1-x}$Sn$\text{}_{x}$ and discuss the effect of a quasi-continuous change of the number of conduction electrons on the gap formation in the Kondo-insulating regime, as well as on the critical behavior appearance near the quantum critical point.
Źródło:
Acta Physica Polonica A; 2007, 111, 4; 487-496
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermoelectric Properties of Heavy Fermion Compound Ce₃Co₄Sn₁₃
Autorzy:
Witas, P.
Kalinowski, L.
Goraus, J.
Fijałkowski, M.
Ślebarski, A.
Powiązania:
https://bibliotekanauki.pl/articles/1385439.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.27.+a
72.15.Eb
72.15.Jf
Opis:
The heavy fermion compound Ce₃Co₄Sn₁₃ was studied in terms of its thermoelectric properties. To enhance its figure of merit we milled the solid sample and then pressed to obtain a consistent granulated material. The main properties, such as the Seebeck coefficient, thermal conductivity and electronic resistivity were measured at low (< 300 K) temperatures for both, the solid and the granulated sample. Thermal conductivity was diminished and the Seebeck coefficient was slightly enhanced, while the resistivity of produced material was increased. We explain it by strong electron scattering on defects and grain boundaries present in the sample. The resulting figure of merit ZT was found to be enhanced almost across the whole measured T region.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 309-311
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Field Dependence of the Electrical Resistivity in Non-Fermi Liquid U$\text{}_{0.05}$Y$\text{}_{0.95}$Al$\text{}_{2}$, U$\text{}_{0.2}$Y$\text{}_{0.8}$Pd$\text{}_{3}$ and UCu$\text{}_{5-x}$Pd$\text{}_{x}$ (x=1.0,0.9)
Autorzy:
Strydom, A. M.
de V. Du Plessis, P.
Powiązania:
https://bibliotekanauki.pl/articles/2014439.pdf
Data publikacji:
2000-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.15.Qm
71.27.+a
72.15.Gd
Opis:
We investigate the influence of applied magnetic fields up to B=8T on the electrical resistivity attemperatures down to 1.5K for three established non-Fermi liquid systems U$\text{}_{0.05}$Y$\text{}_{0.95}$Al$\text{}_{2}$, U$\text{}_{0.2}$Y$\text{}_{0.8}$Pd$\text{}_{3}$ and UCu$\text{}_{5-x}$Pd$\text{}_{x}$ (x=1.0,0.9). We follow the approach that an unconventional Kondo mechanism is often seen to be operative at low temperatures in some non-Fermi liquid systems where there are logarithmic or power-law divergences in the temperature dependences of magnetic susceptibility, the specific heat, and the electrical resistivity. In the above systems the incoherent Kondo scattering dominates the electrical resistivity ρ(T) at higher temperatures, while at low temperatures ρ~T$\text{}^{n}$ with n≈1, instead of n=2 as expected for a Fermi-liquid. We show how the power-law dependence is affected by a magnetic field. The isothermal magnetoresistivity as a function of field is analysed in terms of the Bethe ansatz description in order to extract values of the characteristic Kondo temperature T$\text{}_{K}$.
Źródło:
Acta Physica Polonica A; 2000, 98, 5; 593-597
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The t-J Model in a Strong Magnetic Field
Autorzy:
Sherman, A.
Powiązania:
https://bibliotekanauki.pl/articles/1384828.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.10.Fd
71.27.+a
71.70.Di
74.72.Gh
Opis:
The normal-state energy spectrum of the two-dimensional t-J model in a homogeneous perpendicular magnetic field B is investigated using the Mori projection operator technique. The density of states at the Fermi level as a function of 1/B reveals both high- and low-frequency oscillations. The high-frequency oscillations correspond to large Fermi surfaces, while the low-frequency components are related to van Hove singularities in the Landau subbands, which stem from their bending due to strong electron correlations. Frequencies of the low-frequency components are of the same order of magnitude as those observed in underdoped cuprates. These components become dominant if smoothing processes are involved. It is shown that despite increased distances between subbands the pseudogap affects only slightly the frequency of density of states oscillations.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 213-215
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Do Van Hove Singularities in Leads Influence Tunneling Current through Quantum Dot?
Autorzy:
Krawiec, M.
Domański, T.
Wysokiński, K. I.
Powiązania:
https://bibliotekanauki.pl/articles/1991636.pdf
Data publikacji:
1998-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.40.Gk
72.15.Qm
71.27.+a
Opis:
Using the Landauer type formula for the current through quantum dot we have studied the influence of the singularities in the density of states in leads on the differential conductance of the system and answered affirmatively the above question. The presence of Van Hove singularities in the leads may induce an additional structure on the conductance vs. voltage curve. The dot itself has been described by the single impurity Anderson model with a very strong "on-dot" Coulomb repulsion. We also simulate the effect of electron-phonon interaction in the dot by allowing for the fluctuations of the "impurity" energy level.
Źródło:
Acta Physica Polonica A; 1998, 94, 3; 411-414
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin Polarons in Two-Dimensional Systems
Autorzy:
Morkowski, J. A.
Powiązania:
https://bibliotekanauki.pl/articles/2011229.pdf
Data publikacji:
2000-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.27.+a
72.10.Di
74.20.Mn
Opis:
The problem of motion of holes on a square lattice of antiferromagnetically ordered spins is considered. An overview of the theory of hole dynamics in the antiferromagnetic background is presented. Motion of a single hole is rather well understood both by numerical and analytical methods. For small but finite concentration of holes a treatment analogous to the standard polaron theory is discussed starting with an exact mapping of the t-J Hamiltonian into holon and pseudospin variables.
Źródło:
Acta Physica Polonica A; 2000, 97, 1; 101-110
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spectral Functions of the Quantum Dot Coupled to Normal and/or Superconducting Leads
Autorzy:
Krawiec, M.
Wysokiński, K. I.
Powiązania:
https://bibliotekanauki.pl/articles/2012885.pdf
Data publikacji:
2000-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.40.Gk
72.15.Qm
71.27.+a
Opis:
We study the spectrum of the quantum dot coupled to two external leads, which may be normal and/or superconducting. The dot is described by the Anderson-Hubbard impurity model in the infinity U limit. The impurity spectral function shows complex behavior depending on the temperature and the state of the leads. For normal leads and at low temperature we observe the appearance of the Kondo resonance, while for BCS-like superconducting leads the bound states emerge due to absence of low energy excitations in the leads.
Źródło:
Acta Physica Polonica A; 2000, 97, 1; 197-200
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Macroscopic and Microscopic Study of a CePdIn Compound
Autorzy:
Klicpera, M.
Javorský, P.
Puente-Orench, I.
Hoser, A.
Powiązania:
https://bibliotekanauki.pl/articles/1030269.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.05.F-
71.27.+a
72.15.Eb
Opis:
The magnetization and electrical resistivity measurements on a CePdIn single crystal as well as its preparation and structural characterization are presented. The negative paramagnetic Curie temperatures indicate antiferromagnetic ground state, the anisotropy of the paramagnetic Curie temperature amounts 22.7 K. No ferromagnetic correlations were indicated. Powder neutron diffraction experiment performed at temperatures down to 0.4 K did not lead to observation of any magnetic peak in diffraction patterns. We estimate the magnetic moment on Ce atoms to be significantly lower than 0.5 μ_{B}. The temperature development of lattice parameters documents the standard thermal expansion of the unit cell; no signs of structural phase transition were observed.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 970-972
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
t-t-J-U Model in Mean-Field Approximation: Coexistence of Superconductivity and Antiferromagnetism
Autorzy:
Abram, M.
Powiązania:
https://bibliotekanauki.pl/articles/1374335.pdf
Data publikacji:
2014-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.27.+a
74.25.Dw
74.72.Gh
Opis:
We discuss the t-J-U model in the mean-field approximation. The role of spin-exchange coupling J and the second nearest hopping t' are examined in the context of the coexistence of superconductivity and antiferromagnetism. Stability of the phases is studied with respect to temperature. The coexistence region exists for the sufficiently large Coulomb repulsion (U>$U_{cr}$), and in the vicinity of the half-filled band (hole doping δ < $δ_{cr}$). The critical hole doping is relatively small ($δ_{cr}$ ≈ 0.006 for J/|t| = 1/3) and linear with respect to J. The decrease of $U_{cr}$ is proportional to J, except the limit of small J (J/|t| < 0.03), where $U_{cr}$ grows rapidly with decreasing J. The effect of the second nearest hopping is limited - the phase diagram does not change in a qualitative manner when the t' value is changed. In the limit of T → 0, SC phase is stable even for large hole-doping (such as δ = 0.5). Additional paramagnetic phase appears for large δ or small U at non-zero temperature. When temperature increases, both SC and AF+SC phase regions are reduced.
Źródło:
Acta Physica Polonica A; 2014, 126, 4a; A-25-A-29
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Transport Properties of the Au-Al-Yb Quasicrystal and Approximant under Hydrostatic Pressure
Autorzy:
Matsukawa, S.
Tanaka, K.
Nakayama, M.
Kunikata, S.
Deguchi, K.
Imura, K.
Ishimasa, T.
Sato, N.
Powiązania:
https://bibliotekanauki.pl/articles/1373322.pdf
Data publikacji:
2014-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.27.+a
72.15.Eb
75.50.Kj
Opis:
The mixed-valence Au-Al-Yb quasicrystal exhibits unusual quantum criticality. Its crystalline approximant behaves like a conventional heavy fermion metal. Due to these novel features, they have attracted much attention recently. To examine the sample dependence of this new type of materials, we have prepared several samples and measured the electrical resistivity both at ambient and high pressures as well as the magnetic susceptibility at ambient pressure. The residual resistivity ratio of the quasicrystals is almost sample independent while the power law exponent n of the electrical resistivity varies from sample to sample. The effective magnetic moment $p_{eff}$ of the quasicrystals is also sample dependent, ranging from about 3.4 to 3.9 $μ_{B}$/Yb, and these values are all smaller than the free $Yb^{3+}$ ion value, confirming the mixed-valence nature. Although the magnitude of n and $p_{eff}$ is sample-dependent, the principal feature of the mixed-valence is confirmed in all the samples studied thus far. A combination of these results indicates correlation between n and $p_{eff}$, suggesting that the 4f electrons may contribute to a scattering mechanism of the conduction electrons. External pressure increases the magnitude of the electrical resistivity and decreases the index n of both the quasicrystal and the approximant. Up to the highest pressure measured in the present study no experimental evidence for a phase transition was found.
Źródło:
Acta Physica Polonica A; 2014, 126, 2; 527-530
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 25

Ta witryna wykorzystuje pliki cookies do przechowywania informacji na Twoim komputerze. Pliki cookies stosujemy w celu świadczenia usług na najwyższym poziomie, w tym w sposób dostosowany do indywidualnych potrzeb. Korzystanie z witryny bez zmiany ustawień dotyczących cookies oznacza, że będą one zamieszczane w Twoim komputerze. W każdym momencie możesz dokonać zmiany ustawień dotyczących cookies