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Wyszukujesz frazę "71.28.-d" wg kryterium: Temat


Tytuł:
Two-Band Model for Coherent Excitonic Condensates
Autorzy:
Apinyan, V.
Kopeć, T.
Powiązania:
https://bibliotekanauki.pl/articles/1398643.pdf
Data publikacji:
2016-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.10.Fd
71.28.+d
71.35.-y
71.10.Hf
Opis:
We consider the excitonic correlations in the two-band solid state system composed of the valence band and conduction band electrons. We treat the phase coherence mechanism in the system by presenting the electron operator as a fermion attached to the U(1) phase-flux tube. The emergent bosonic gauge field, related to the phase variables appears to be crucial for the coherent Bose-Einstein condensation of excitons. We calculate the normal excitonic Green functions, and the single-particle density of states functions being a convolution between bosonic and fermionic counterparts. We obtain the total density of states as a sum of two independent parts. For the coherent normal fermionic density of states, there is no hybridization-gap found in the system due to strong coherence effects and phase stiffness.
Źródło:
Acta Physica Polonica A; 2016, 130, 2; 621-624
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Features of Energy Spectrum of Pb$\text{}_{1-x}$Mn$\text{}_{x}$Te Doped with V
Autorzy:
Artamkin, A. I.
Dobrovolsky, A. A.
Dziawa, P.
Story, T.
Slynko, E. I.
Slynko, V. E.
Ryabova, L. I.
Khokhlov, D. R.
Powiązania:
https://bibliotekanauki.pl/articles/2046904.pdf
Data publikacji:
2006-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.Nr
71.28.+d
71.55.-i
72.40.+w
Opis:
Recently new effects that are not characteristic of undoped lead telluride, such as the Fermi level pinning, giant negative magnetoresistance, were observed in Pb$\text{}_{1-x}$Mn$\text{}_{x}$Te alloys doped with transition and rare earth elements - Cr, Mo, Yb. We have studied transport and magnetic properties of Pb$\text{}_{1-x}$Mn$\text{}_{x}$Te doped with another transition element - vanadium. A series of Pb$\text{}_{1-x}$Mn$\text{}_{x}$Te(V) samples of different composition and degree of doping was investigated. It was observed that the resistivity demonstrates activation behavior at low temperatures for the samples with considerable amount of vanadium as well as for the samples without vanadium. The activation energy is proportional to the Mn content. In some of the samples, photoconductivity was observed at low temperatures. The results are discussed in terms of a model assuming formation of the impurity level by the vanadium impurity and the effect of the Fermi level pinning by this level.
Źródło:
Acta Physica Polonica A; 2006, 110, 2; 151-156
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Transport and Magnetic Properties of Pb$\text{}_{1-x}$Mn$\text{}_{x}$Te Doped with Cr and Mo
Autorzy:
Artamkin, A. I.
Kozhanov, A. E.
Arciszewska, M.
Dobrowolski, W. D.
Story, T.
Slynko, E. I.
Slynko, V. E.
Khokhlov, D. R.
Powiązania:
https://bibliotekanauki.pl/articles/2038231.pdf
Data publikacji:
2004-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.28.+d
Opis:
Transport and magnetic properties of Pb$\text{}_{1-x}$Mn$\text{}_{x}$Te (x<0.18) semiconductor alloys doped with Cr or Mo are investigated in a broad range of temperatures and magnetic fields. In PbMnTe(Cr) alloys the Fermi level may be pinned either in the conduction band or in the energy gap, depending on Mn concentration. In PbMnTe(Mo) alloys the pinning of the Fermi level is observed in the valence band as well as in the energy gap. In the latter case persistent photoconductivity is observed at low temperatures. The analysis of the temperature dependence of magnetic susceptibility shows that PbMnTe alloys doped with Cr or Mo are Curie-Weiss paramagnets revealing weak antiferromagnetic interactions between magnetic ions.
Źródło:
Acta Physica Polonica A; 2004, 106, 2; 223-231
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Tunneling Spectroscopy Studies of $SmB_6$ and $YbB_{12}$
Autorzy:
Baťková, M.
Baťko, I.
Konovalova, E.
Shitsevalova, N.
Powiązania:
https://bibliotekanauki.pl/articles/1813633.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.28.+d
75.30.Mb
73.40.Gk
Opis:
Reported electron tunneling studies of $SmB_6$ and $YbB_{12}$ in the temperature region with a strongly temperature activated transport reveal a qualitative change of tunneling regime upon cooling. While the differential conductance curves above 50 K resemble the tunneling between two different metals, the spectra observed at 4.2 K are typical of the tunneling between a metal and a (narrow-gap) valence fluctuating semiconductor.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 255-258
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ground States of the Falicov-Kimball Model Extended by Nonlocal Coulomb Interactions
Autorzy:
Čenčariková, H.
Farkašovský, P.
Žonda, M.
Powiązania:
https://bibliotekanauki.pl/articles/1813654.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Lp
71.27.+a
71.28.+d
Opis:
The small-cluster exact-diagonalizations are used to study the ground states of the Falicov-Kimball model extended by nonlocal Coulomb interactions (the nearest-neighbour interaction $U_{nn}$ and the correlated hopping t'). It is shown that the ground-state phase diagrams found for the conventional Falicov-Kimball model are strongly changed when the nonlocal interactions are added. This is illustrated for two selected values of the on-site Coulomb interaction (U) that represent typical behaviours of the model in the intermediate and strong coupling limit. A number of remarkable results are found. (i) The phase separation takes place for a wide range of $U_{nn}$ and t' in both interaction limits. (ii) New types of inhomogeneous charge ordering are observed for nonzero $U_{nn}$ and t'. (iii) Depending on the values of $U_{nn}$ and t', the model is able to describe both the continuous as well as discontinuous changes of the f-electron occupation number.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 287-290
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ground States of the Spin-One-Half Falicov-Kimball Model with Hunds Rule Coupling in Two Dimensions
Autorzy:
Čenčariková, H.
Farkašovský, P.
Tomašovičová, N.
Žonda, M.
Powiązania:
https://bibliotekanauki.pl/articles/1810314.pdf
Data publikacji:
2009-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Lp
71.27.+a
71.28.+d
Opis:
The spin-one-half Falicov-Kimball model with spin-dependent on-site interaction between localized (f) and itinerant (d) electrons is studied by small-cluster exact-diagonalization calculations and a well-controlled approximative method in two dimensions. The results obtained are used to categorize the ground-state configurations according to common features (charge and spin ordering) for all f and d electron concentrations ($n_f$ and $n_d$) on finite square lattices. It is shown that only a few configuration types form the basic structure of the charge phase diagram in the $n_f-n_d$ plane. In particular, the largest regions of stability correspond to the phase segregated configurations and configurations that can be considered as mixtures of chessboard configurations and the full (empty) lattice. Since the magnetic phase diagram is much richer than the charge phase diagram, the magnetic superstructures are examined only at selected values of f and d electron concentrations.
Źródło:
Acta Physica Polonica A; 2009, 115, 1; 101-103
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ground State Phase Diagrams of the Extended Hubbard Model with Repulsive Pair-Hopping Interaction for Nonfrustrated 2D Lattice
Autorzy:
Czart, W.
Robaszkiewicz, S.
Powiązania:
https://bibliotekanauki.pl/articles/1385232.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.20.-z
71.28.+d
74.20.Mn
Opis:
We analyze the extended Hubbard model with pair-hopping interaction J, i.e. the Penson-Kolb-Hubbard model, in the case of repulsive J (J < 0) within the (broken symmetry) Hartree-Fock approximation. We focus our study on the effects of on-site U interaction on the mutual stability of magnetic, charge-ordered, and superconducting states including the eta-pairing phase, i.e. the state with the Cooper-pair center-of-mass momentum q=Q. The ground state phase diagrams are obtained for arbitrary particle concentration n on nonfrustrated d=2 square lattice.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 275-277
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ground State Phase Properties of the Penson-Kolb-Hubbard Model with Attractive Pair-Hopping Interaction
Autorzy:
Czart, W.
Robaszkiewicz, S.
Powiązania:
https://bibliotekanauki.pl/articles/1385235.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.20.-z
71.28.+d
74.20.Mn
Opis:
We study the ground state phase diagrams of the extended Hubbard model with the pair-hopping interaction J, i.e. the Penson-Kolb-Hubbard model. We concentrate on the case of attractive J (J > 0) which can stabilise s-wave pairing superconductivity in the system and competes with the on-site repulsive U. The evolution of the phase diagrams and order parameters for arbitrary electron density and representative values of the interaction parameters are analyzed within the (broken symmetry) Hartree-Fock approximation. The calculations are performed for the case of nearest-neighbors electron hopping t on the d=2 square lattice.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 278-280
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Phase Diagrams of the Penson-Kolb-Hubbard Model with Repulsive Pair-Hopping Interaction
Autorzy:
Czart, W.
Robaszkiewicz, S.
Powiązania:
https://bibliotekanauki.pl/articles/1398641.pdf
Data publikacji:
2016-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.20.-z
71.28.+d
74.20.Mn
Opis:
We study the extended Hubbard model with on-site density-density U and intersite pair hopping J interactions, i.e. the Penson-Kolb-Hubbard model. This report focuses mainly on the properties of the model at T ≥q 0 in the case of repulsive J (J < 0) which may stabilize superconductivity with η-pairing. The analysis is performed within the (broken symmetry) Hartree-Fock approximation for arbitrary interaction parameters (J < 0 and U) and electron concentration (0 < n < 2) on the d = 2 square lattice. The phase diagrams of the model at T=0 and at finite temperatures are examined taking into account magnetic and charge-ordered phases and superconducting states with η- and s-wave pairing.
Źródło:
Acta Physica Polonica A; 2016, 130, 2; 613-616
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Coulomb Interactions on the Properties of Induced Pairing Model
Autorzy:
Czart, W. R.
Robaszkiewicz, St.
Powiązania:
https://bibliotekanauki.pl/articles/2027440.pdf
Data publikacji:
2001-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.20.-z
74.20.Mn
71.28.+d
74.25.Ha
Opis:
We study the superconducting properties of a model of coexisting itinerant carriers and local pairs with finite binding energy, taking into account the effects of Coulomb (density-density) and direct pair hopping interactions. The evolution of the phase diagrams and superfluid characteristics with electron concentration, interaction parameters and the relative position of the bands is examined. The model is found to exhibit several kinds of superconducting behaviors ranging from the BCS-like to the local-pair-like. The relevance of the obtained results to the interpretation of experimental data for the doped bismuthates (Ba$\text{}_{1-x}$K$\text{}_{x}$BiO$\text{}_{3}$ and BaPb$\text{}_{1-x}$BiO$\text{}_{3}$) is pointed out.
Źródło:
Acta Physica Polonica A; 2001, 100, 1; 75-88
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Superconducting Characteristics of the Penson-Kolb Model
Autorzy:
Czart, W. R.
Robaszkiewicz, S.
Powiązania:
https://bibliotekanauki.pl/articles/2012898.pdf
Data publikacji:
2000-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.20.-z
71.28.+d
74.25.Ha
Opis:
We study superconducting properties of the Penson-Kolb model, i.e. the tight-binding model with the pair-hopping (intersite charge exchange) interaction J. The evolution of the critical fields, the coherence length, the Ginzburg ratio, and the London penetration depth with particle concentration n and pairing strength are determined. The results are compared with those found earlier for the attractive Hubbard model.
Źródło:
Acta Physica Polonica A; 2000, 97, 1; 217-220
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Superconducting Properties of theη-Pairing State in the Penson-Kolb-Hubbard Model
Autorzy:
Czart, W. R.
Robaszkiewicz, S.
Powiązania:
https://bibliotekanauki.pl/articles/2041460.pdf
Data publikacji:
2004-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.20.-z
71.28.+d
74.25.Ha
Opis:
The Penson-Kolb-Hubbard model, i.e. the Hubbard model with the pair-hopping interaction J is studied. We focus on the properties of the superconducting state with the Cooper-pair center-of-mass momentum q= Q (η-phase). The transition into theη-phase, which is favorized by the repulsive J (J<0) is found to occur only above some critical value |J$\text{}_{c}$|, dependent on band filling, on-site interaction U and band structure, and the system never exhibits standard BCS-like features. This is in obvious contrast with the properties of the isotropic s-wave state, stabilized by the attractive J and attractive U, which exhibit at T=0 a smooth crossover from the BCS-like limit to that of tightly bound pairs with increasing pairing strength.
Źródło:
Acta Physica Polonica A; 2004, 106, 5; 709-713
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Superconductivity of the Two-Dimensional Penson-Kolb Model
Autorzy:
Czart, W. R.
Robaszkiewicz, S.
Powiązania:
https://bibliotekanauki.pl/articles/2029270.pdf
Data publikacji:
2001-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.20.-z
71.28.+d
74.25.Ha
Opis:
Two-dimensional (d=2) Penson-Kolb model, i.e. the tight-binding model with the pair-hopping (intersite charge exchange) interaction, is considered and the effects of phase fluctuations on the s-wave superconductivity of this system are discussed within the Kosterlitz-Thouless scenario. The London penetration depth λ at T=0, the Kosterlitz-Thouless critical temperature T$\text{}_{c}$, and the Hartree-Fock approximation critical temperature T$\text{}_{p}$ are determined as a function of particle concentration and interaction. The Uemura type plots (T$\text{}_{c}$ vs.λ$\text{}^{-2}$(0)) are derived. Beyond weak coupling and for low concentrations they show the existence of universal scaling: T$\text{}_{c}$ ~1/λ$\text{}^{2}$(0), as it was previously found for the attractive Hubbard model and for the models with intersite electron pairing.
Źródło:
Acta Physica Polonica A; 2001, 100, 6; 885-895
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Superfluid Characteristics of Induced-Pairing Model
Autorzy:
Czart, W. R.
Szkudlarek, M.
Robaszkiewicz, S.
Powiązania:
https://bibliotekanauki.pl/articles/1955834.pdf
Data publikacji:
1997-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.28.+d
74.25.Ha
74.20.-z
Opis:
We study the electromagnetic and thermodynamic properties of a model of coexisting local electron pairs and itinerant carriers coupled via the intersubsystem charge exchange. The calculations of the London penetration depth, the energy gap, the magnetic critical fields and the coherence length in the superconducting phase are performed. The effects of reduced binding energy of local pairs are discussed.
Źródło:
Acta Physica Polonica A; 1997, 91, 2; 415-418
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Quest for Band Renormalization and Self-Energy in Correlated f-Electron Systems
Autorzy:
Durakiewicz, T.
Riseborough, P.
Batista, C.
Yang, Y.
Oppeneer, P.
Joyce, J.
Bauer, E.
Graham, K.
Powiązania:
https://bibliotekanauki.pl/articles/1538778.pdf
Data publikacji:
2010-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
79.60.-i
71.28.+d
74.25.Jb
Opis:
Coexisting low-energy scales are observed in f-electron materials. The information about some of low-energy scales is imprinted in the electron self-energy, which can be measured by angle-resolved photoemission (ARPES). Such measurements in d-electron materials over the last decade were based on high energy- and momentum- resolution ARPES techniques used to extract the self-energy information from measured spectra. Simultaneously, many-body theoretical approaches have been developed to find a link between the self-energy and many-body interactions. Here we show the transcription of such methods from d-electrons to f-electrons by presenting the first example of low energy scales in the f-electron material $USb_2$, measured with synchrotron-based ARPES. The proposed approach will help in answering the fundamental questions about the complex nature of the heavy fermion state.
Źródło:
Acta Physica Polonica A; 2010, 117, 2; 264-267
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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