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Wyszukujesz frazę "71.45.Lr" wg kryterium: Temat


Tytuł:
Electron Liquids in Coupled Quantum Wells
Autorzy:
Świerkowski, L.
Szymański, J.
Neilson, D.
Powiązania:
https://bibliotekanauki.pl/articles/1929610.pdf
Data publikacji:
1993-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.40.Lq
71.45.Gm
71.45.Lr
Opis:
A system comprising of two adjacent layers of conduction electrons or alternatively a layer of electrons and a layer of holes can exhibit novel instabilities in the liquid phase towards inhomogeneous ground states. The carriers in the two layers can couple to each other through the Coulomb interaction but they are not permitted to tunnel so that the charges in one layer act as a polarisable background for the other layer. The presence of a second layer encourages the formation of novel ground states with inhomogeneous density distributions. We find theoretical evidence for the existence of charge density wave ground states and also a coupled Wigner crystal. These exist at much higher densities than the Wigner crystallisation density for the single layer case. The existence of these inhomogeneous ground states leads to significant modifications of the low lying excitation spectrum in the uniform liquid phase. Near the transitions to both the charge density wave and the coupled Wigner crystal phases we find evidence of the development in the liquid phase of new soft mode excitations of finite wave number q that are precursors of the inhomogeneous ground states. Near the transition to the coupled Wigner crystal we observe a strong tendency of the single particle excitation spectrum for the liquid phase to renormalise into a single line that has a dispersion closely resembling the phonon dispersion curve for the solid.
Źródło:
Acta Physica Polonica A; 1993, 84, 3; 445-457
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On a Field-Induced Spin-Density Wave in Bechgaard Salts
Autorzy:
Apostol, M.
Powiązania:
https://bibliotekanauki.pl/articles/1931366.pdf
Data publikacji:
1994-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Fv
75.50.Rr
71.45.Lr
Opis:
A new type of field-induced spin-density wave is shown to occur in a weak-coupling layered model which may be relevant for the highly anisotropic electronic structure of the Bechgaard salts. The modulation vector of this instability is perpendicular to the layers and close to the direction of the magnetic field applied perpendicular to the reciprocal layers. The magnitude of the modulation vector, order parameter and critical temperature have an oscillatory dependence on the magnitude of the magnetic field.
Źródło:
Acta Physica Polonica A; 1994, 85, 6; 971-978
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Peierls Instability and Charge-Density-Wave Transport in Fluoranthene and Perylene Radical Cation Salts
Autorzy:
Brütting, W.
Riess, W.
Powiązania:
https://bibliotekanauki.pl/articles/1933357.pdf
Data publikacji:
1995-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.45.Lr
71.30.+h
72.10.Bg
72.80.Le
Opis:
Fluoranthene and perylene radical cation salts are quasi-one-dimensional conductors, which show a Peierls transition to a charge-density-wave ground state. Radical cation salts with different stoichiometries composed of the aromatic donor molecules fluoranthene (Fa = C$\text{}_{16}$H$\text{}_{10}$) or perylene (Per = C$\text{}_{20}$H$\text{}_{12}$) and the counterion X¯ = PF¯$\text{}_{6}$ were investigated. We find that the temperature dependence of the electrical conductivity and the properties in the charge-density-wave ground state strongly depend on the composition of the crystals. When fluoranthene is replaced by perylene, the Peierls transition is shifted from 180 K to 120 K and the ground state energy gap decreases from values of 120-180 meV to 60-80 meV. In the charge-density-wave ground state the threshold field for nonlinear conductivity varies between 0.1 and 1 V/cm for different systems. Our results indicate that disorder, three-dimensional coupling and commensurability effects play an important role for the transport properties of these systems.
Źródło:
Acta Physica Polonica A; 1995, 87, 4-5; 785-790
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stabilized 1D Metal in TTF(Ni(dmit)$\text{}_{2}$)$\text{}_{2}$ through Very Weak Coupling between Phonons and Weakly Correlated Fermions
Autorzy:
Doublet, M. L.
Malfant, I.
Hebrard, S.
Canadell, E.
Gaultier, J.
Chasseau, D.
Legros, J. P.
Brossard, L.
Powiązania:
https://bibliotekanauki.pl/articles/1933351.pdf
Data publikacji:
1995-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.Hk
71.45.Lr
61.66.Hq
Opis:
Extended Hückel band structure calculations derived from low temperature X-ray structural data, provide evidence, as temperature decreases, for an increasing 1D character of the multiparallel bands of the TTF(Ni(dmit)$\text{}_{2}$)$\text{}_{2}$ compound. This result is discussed within the monotonous metallic behaviour of the weakly correlated fermions gas, despite condensations of charge density wave instabilities.
Źródło:
Acta Physica Polonica A; 1995, 87, 4-5; 781-784
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Towards a Unified View of Electron-Phonon Coupling in 1D Solids
Autorzy:
Girlando, A.
Painelli, A.
Soos, Z. G.
Powiązania:
https://bibliotekanauki.pl/articles/1933319.pdf
Data publikacji:
1995-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.38.+i
71.27.+a
71.45.Lr
Opis:
We analyze the effect of on-site and on-bond electron-phonon (e-ph) coupling in different classes of quasi one-dimensional (1D) solids in terms of a single model. The model was originally developed to account for e-ph coupling in charge transfer crystals and to interpret their vibrational spectra. The same model is extended to conjugated polymers, showing that important information about the electronic structure can be obtained through a careful analysis of vibrational data. Evidence of e-ph coupling in the spectra of halogen-bridged transition-metal complexes is also presented. The unified model thus applies to different classes of 1D systems and yields transferable e-ph coupling constants.
Źródło:
Acta Physica Polonica A; 1995, 87, 4-5; 735-742
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Superconductivity versus Diagonal Disorder in the (Hard-Core) Boson-Fermion Model
Autorzy:
Pawłowski, G.
Robaszkiewicz, S.
Micnas, R.
Powiązania:
https://bibliotekanauki.pl/articles/2041476.pdf
Data publikacji:
2004-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.45.Lr
71.55.Jv
74.20.-z
Opis:
The influence of randomness of local pair site energies on superconducting properties of a system of coexisting local pairs and itinerant electrons described by the (hard-core) boson-fermion model is analyzed within variational BCS Hartree-Fock approach. Assuming the rectangular distribution function of the random potential the phase diagrams, critical temperatures, and the chemical potential behaviours are determined.
Źródło:
Acta Physica Polonica A; 2004, 106, 5; 745-749
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electron Orderings of Half-Filled Extended Hubbard Models with Spin- and Charge-Exchange Interaction
Autorzy:
Czart, W. R.
Robaszkiewicz, S.
Powiązania:
https://bibliotekanauki.pl/articles/2046752.pdf
Data publikacji:
2006-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.10.Fd
75.10.-b
75.30.Gw
71.45.Lr
74.20.-z
Opis:
The electron orderings of the half-filled extended Hubbard models (i) with anisotropic spin-exchange interactions (the t-U-J$\text{}_{ǁ}$-J$\text{}_{⊥}$ model) and (ii) with charge-exchange interaction (the t-U-I model) are discussed. In particular, we present new results concerning the phase diagrams of the model (i) in the case of uniaxial spin exchange (J$\text{}_{ǁ}$≢0) for d-dimensional hypercubic lattices (1≤d≤∞) and conclude about the basic effects of the particular spin- and charge-exchange interaction terms (J$\text{}_{ǁ}$, J$\text{}_{⊥}$, and I) in both models.
Źródło:
Acta Physica Polonica A; 2006, 109, 4-5; 577-582
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin-Dependent Tunneling in a Magnetic Field for Junctions Involving Normal and Superconducting CDW Metals
Autorzy:
Ekino, T.
Gabovich, A. M.
Suan Li, Mai
Pękała, M.
Szymczak, H.
Voitenko, A. I.
Powiązania:
https://bibliotekanauki.pl/articles/2046730.pdf
Data publikacji:
2006-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.45.Lr
74.50.+r
85.75.-d
Opis:
The voltage, V, dependences of the differential tunnel conductance G(V) were calculated for two kinds of junctions involving normal and superconducting charge-density-wave metals (CDWMs) in the external magnetic field H. The first is a non-symmetrical junction with a CDWM electrode being biased with respect to a ferromagnet. Calculations show that the paramagnetic splitting occurs between spin-up and spin-down components of G(V), similar to what is observed when a superconducting electrode is used instead of the CDWM one. The second setup is symmetric (CDWM-I-CDWM), where I denotes an insulator. If at least one of the CDWM electrodes is normal and H≠0, G(V) will also be spin-split.
Źródło:
Acta Physica Polonica A; 2006, 109, 4-5; 477-484
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Superconductivity, Charge Density Wave and Charge Kondo States in Systems of Coexisting Itinerant Electrons and Local Pairs
Autorzy:
Sidowski, M.
Robaszkiewicz, S.
Powiązania:
https://bibliotekanauki.pl/articles/2046796.pdf
Data publikacji:
2006-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.20.Mn
74.20.-z
75.30.Mb
71.45.Lr
Opis:
The properties of a system of coexisting local pairs and itinerant electrons described by the (hard-core) boson-fermion model are discussed. For the first time we include into analysis of the model not only the superconducting and non-ordered (normal) states but also the charge density wave phases as well as the so-called charge Kondo state. Within an extended mean-field approximation, a mutual stability of charge density wave, superconducting and charge Kondo states are determined at T = 0 in the case of half-filled fermionic and bosonic bands.
Źródło:
Acta Physica Polonica A; 2006, 109, 4-5; 647-652
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Charge-Density-Wave Origin of Dip-Hump Structures in the Tunnel Spectra of Bi$\text{}_{2}$Sr$\text{}_{2}$CaCu$\text{}_{2}$O$\text{}_{8+δ}$
Autorzy:
Ekino, T.
Gabovich, A. M.
Li, M. S.
Pękała, M.
Szymczak, H.
Voitenko, A. I.
Powiązania:
https://bibliotekanauki.pl/articles/2047318.pdf
Data publikacji:
2007-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.43.Jn
71.45.Lr
74.50.+r
74.81.-g
Opis:
We calculated the differential conductance G as the function of the bias voltage V across the tunnel junction between a normal metal or a conventional superconductor and an inhomogeneous superconductor with charge density waves. Spatial averaging over random domains with varying superconducting and normal state properties was carried out. For high-T$\text{}_{c}$ oxides, irregularly distorted charge density wave patterns with spatially scattered values of various parameters were earlier shown to manifest themselves in a great body of experimental data. The results of calculation were applied to explain the well-known dip-hump structure in the G(V) dependence for Bi$\text{}_{2}$Sr$\text{}_{2}$CaCu$\text{}_{2}$O$\text{}_{8+δ}$ and other cuprates.
Źródło:
Acta Physica Polonica A; 2007, 111, 4; 573-580
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Superconductivity and Charge-Density Wave Phase in the Holstein Model: a Weak Coupling Limit
Autorzy:
Grzybowski, P.
Micnas, R.
Powiązania:
https://bibliotekanauki.pl/articles/2047304.pdf
Data publikacji:
2007-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.38.-k
71.45.Lr
74.20.Mn
Opis:
The variational canonical transformation method has been applied to the Holstein model to obtain an effective polaronic Hamiltonian, which is subsequently analyzed in the limit of a weak effective electron-electron interaction. A competition between the superconducting and charge-density wave phases has been studied in the light of strong polaronic effects. The phase diagrams illustrating the system evolution from adiabatic to anti-adiabatic limit are presented.
Źródło:
Acta Physica Polonica A; 2007, 111, 4; 453-463
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Charge Ordering and Phase Separations in the Spinless Fermion Model with Repulsive Intersite Interaction
Autorzy:
Czart, W.
Robaszkiewicz, S.
Tobijaszewska, B.
Powiązania:
https://bibliotekanauki.pl/articles/1812286.pdf
Data publikacji:
2008-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.10.Fd
71.30.+h
71.45.Lr
64.75.Gh
Opis:
We study a simple effective model for description of charge orderings in narrow band materials, i.e. the spinless fermion model with repulsive intersite interaction W. The analysis is concentrated on the problem of phase separations and the effects of next-nearest neighbor hopping $t_2$ on the charge ordered states in this system. The cases of d-dimensional (d≥2) hypercubic lattices are considered for arbitrary particle concentration (0 < n < 1). Within the broken symmetry Hartree-Fock approximation the phase diagrams as a function of W and n are evaluated for representative cases. The results for $t_2$ ≠ 0 are compared with those found for the case with nearest neighbor hopping only.
Źródło:
Acta Physica Polonica A; 2008, 114, 1; 129-134
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pseudogap-Like Phenomena in Cuprates as a Manifestation of Charge-Density Waves
Autorzy:
Ekino, T.
Gabovich, A.
Voitenko, A.
Suan Li, Mai
Szymczak, H.
Pękała, M.
Powiązania:
https://bibliotekanauki.pl/articles/1812272.pdf
Data publikacji:
2008-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.43.Jn
71.45.Lr
74.50.+r
74.81.-g
Opis:
Differential conductance G as a function of the bias voltage V was measured for break-junctions of superconducting $Bi_2Sr_2CaCu_2O_{8+δ}$ and $YBa_2Cu_3O_{7-δ}$. The dependences G(V) for both materials clearly demonstrate the so-called dip-hump structures outside the gap region. A theory, which suggests the charge-density-wave origin of the dip-hump structures and explains its specific form by intrinsic inhomogeneity of cuprate materials, was developed. The well-known pseudogap features in the tunnel spectra of high-$T_c$ oxides found both below and above the superconducting critical temperature are also described by the theory, which testifies that both the pseudogap and the dip-hump structures have the same origin. Competing theories and various G(V) peculiarities found for a number of superconducting oxides are briefly discussed.
Źródło:
Acta Physica Polonica A; 2008, 114, 1; 59-66
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Terahertz Resonant Detection by Plasma Waves in Nanometric Transistors
Autorzy:
Teppe, F.
El Fatimy, A.
Boubanga, S.
Knap, W.
Seliuta, D.
Valusis, G.
Chenaud, B.
Powiązania:
https://bibliotekanauki.pl/articles/1813191.pdf
Data publikacji:
2008-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.Nr
71.45.Lr
72.30.+q
Opis:
The plasma waves in gated two-dimensional electron gas have a linear dispersion law, similar to the sound waves. The transistor channel is acting as a resonator cavity for the plasma waves, which can reach frequencies in the THz range for a sufficiently short gate length field effect transistors. A variety of possible applications of field effect transistor operating as a THz device were suggested. In particular, it was shown that the nonlinear properties of plasma oscillations can be utilized for THz tunable detectors. During the last few years THz detection related to plasma wave instabilities in nanometer size field effect transistors was demonstrated experimentally. In this work we review our recent experimental results on the resonant plasma wave detection at cryogenic and room temperatures.
Źródło:
Acta Physica Polonica A; 2008, 113, 3; 815-820
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Charge Ordering and Phase Separations in the Molecular Crystal Model
Autorzy:
Czart, W.
Grzybowski, P.
Robaszkiewicz, S.
Powiązania:
https://bibliotekanauki.pl/articles/1537090.pdf
Data publikacji:
2010-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.10.Fd
71.30.+h
71.45.Lr
64.75.Gh
Opis:
We analyse the ground state phase diagrams and thermodynamic properties of charge orderings in narrow band materials using the molecular crystal model in the static limit. We present results for the hypercubic lattices in dimensions d = 2 and d = ∞. We focus our study on the problem of phase separations involving charge orderings and the effects of next-nearest-neighbor hopping $(t_2)$ on the charge ordered states in these systems. The ground state phase diagrams are evaluated for a few representative cases. Results for the molecular crystal model are compared with those obtained previously for the spinless fermion model with repulsive intersite interaction W.
Źródło:
Acta Physica Polonica A; 2010, 118, 2; 369-372
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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