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Wyszukujesz frazę "71.10.+w" wg kryterium: Temat


Tytuł:
Time-Reversal Invariant Topological Superconductivity in Quasi-One-Dimensional Structures
Autorzy:
Mammadova, S.
Nakhmedov, E.
Alekperov, O.
Powiązania:
https://bibliotekanauki.pl/articles/1398788.pdf
Data publikacji:
2016-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.78.-w
71.10.Pm
71.70.Ej
74.50.+r
Opis:
It is shown that a time-reversal invariant topological superconductivity can be realized in a quasi-one-dimensional structure, which is fabricated by filling the superconducting materials into the periodic channel of dielectric matrices like zeolite and asbestos under high pressure. The topological superconducting phase sets up in the presence of large spin-orbit interactions when s-wave intra-wire and d-wave inter-wire pairings take place. Kramers pairs of Majorana bound states emerge at the edges of each wire. The time-reversal topological superconductor belongs to DIII class of symmetry with a Z₂ invariant.
Źródło:
Acta Physica Polonica A; 2016, 129, 4; 800-802
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study of the Mott Transition in the Three-Dimensional Hubbard Model
Autorzy:
Mancini, F.
Turkowski, V.
Powiązania:
https://bibliotekanauki.pl/articles/2030509.pdf
Data publikacji:
2002-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.10.-w
71.10.Fd
71.30.+h
Opis:
The Mott-Hubbard transition in the three-dimensional Hubbard model is studied by means of the composite operator method. Analytical and numerical calculations show the existence of a critical value U$\text{}_{c}$ of the Coulomb interaction which separates paramagnetic insulating and metallic phases. In the composite operator method the ratio U$\text{}_{c}$/W, where W is the band width, has the same value as in the two-dimensional case. The ground state of the Mott insulator is characterized by a local antiferromagnetic order where the electrons keep some mobility, but this latter must be compatible with the local ordering. By analyzing the intersite hopping it is possible to establish that some correlation functions behave as order parameters in the insulating phase.
Źródło:
Acta Physica Polonica A; 2002, 101, 4; 505-523
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Static Local Field Factor and Ground State Properties of Interacting Electron Gas
Autorzy:
Sarkar, A.
Haldar, S.
Roy, D.
Sen, D.
Powiązania:
https://bibliotekanauki.pl/articles/2038378.pdf
Data publikacji:
2004-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.10.-w
71.45.Gm
Opis:
In the most general case, the calculation of the static local field factor G(q) for the unpolarised electron gas requires the knowledge of exchange-correlation energy functionals for both the parallel and antiparallel relative spin orientations of the electron gas system. Accurate density interpolation formulae using the quantum Monte Carlo data of Ceperley-Alder for the correlation energy of electron gas in both the "para" and "ferro" states, respectively, in the given density range are used for the calculation of G( q). Fulfilment of relevant consistency criteria is ensured and the local field factor so obtained renders significant improvement of ab initio pseudopotential calculation of effective interaction of Al. The Levin like interpolant of the correlation energy Ceperley-Alder data has been further used to study the ground state properties of the electron gas. It is also noted that a better understanding of the interacting electron gas properties requires a more accurate spin interpolation formula for the correlation energy than the existing ones.
Źródło:
Acta Physica Polonica A; 2004, 106, 4; 497-514
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Specific Heat and the Ground State of NiO
Autorzy:
Radwanski, R.
Ropka, Z.
Powiązania:
https://bibliotekanauki.pl/articles/1812327.pdf
Data publikacji:
2008-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.10.-w
75.10.-b
75.10.Dg
Opis:
Working in the strongly-correlated crystal-field approach and in the strong hybridization limit we calculated the temperature dependence of the heat capacity of NiO in a wide temperature range, from zero temperature to 1200 K. Our calculations reproduce reasonably well experimental dependence including the λ-type peak at $T_N$ of 525 K.
Źródło:
Acta Physica Polonica A; 2008, 114, 1; 213-217
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Some Properties of the Model of a~Superconductor with Pair Hopping and Magnetic Interactions at Half-Filling
Autorzy:
Kapcia, K.
Powiązania:
https://bibliotekanauki.pl/articles/1431185.pdf
Data publikacji:
2012-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.10.Fd
71.10.-w
74.20.-z
74.81.-g
75.30.Fv
Opis:
We present our preliminary studies of an effective model of a superconductor with short coherence length involving magnetic interactions. The Hamiltonian considered consists of (i) the effective on-site interaction U, (ii) the intersite magnetic exchange interactions ($J^z,$ $J^{xy}$) between nearest-neighbors and (iii) the intersite charge exchange term I, determining the hopping of electron pairs between nearest-neighbor sites. In the analysis of the phase diagrams and thermodynamic properties of this model for half-filling (n=1) we have adopted the variational approach, which treats the on-site interaction term exactly and the intersite interactions within the mean-field approximation. One finds that the system considered can exhibit very interesting multicritical behaviors (including tricritical, critical-end and bicritical points) caused by the competition between magnetism and superconductivity, even for n=1. Our investigations show that, depending on the values of interaction parameters, the system at half-filling can exhibit three homogeneous phases: superconducting (SS), (anti-)ferromagnetic (F) and nonordered (NO). The transitions between ordered phases (SS, F) and the NO phase can be first order as well as second order ones, whereas SS-F transition is first order one. Temperature dependencies of the order parameters and thermodynamic properties of the system at the sequence of transitions: SS→F→NO with increasing temperature for J/I=0.3, U/I_0 = 0.69 and n=1 are also presented.
Źródło:
Acta Physica Polonica A; 2012, 121, 4; 733-737
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Some Exact Results for the Zero-Bandwidth Extended Hubbard Model with Intersite Charge and Magnetic Interactions
Autorzy:
Kapcia, K.
Kłobus, W.
Robaszkiewicz, S.
Powiązania:
https://bibliotekanauki.pl/articles/1385252.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.10.Fd
71.10.-w
71.10.Hf
71.45.Lr
75.30.Fv
Opis:
The extended Hubbard model in the zero-bandwidth limit is studied. The effective Hamiltonian consists of (i) on-site U interaction, (ii) intersite density-density interaction W, and (iii) Ising-like magnetic exchange interaction J between the nearest-neighbors. We present rigorous (and analytical) results obtained within the transfer-matrix method for 1D chain in two particular cases: (a) W=0 and n=1; (b) U → +∞ and n=1/2 (W ≠ 0, J ≠ 0). We obtain the exact formulae for the partition functions which enables to calculate thermodynamic properties such as entropy, specific heat (c), and double occupancy per site. In both cases the system exhibits an interesting temperature dependence of c involving a characteristic two-peak structure. There are no phase transitions at finite temperatures and the only transitions occur in the ground state.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 284-286
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Singlet-Triplet Switching Induced by Electric Field in Triple Quantum Dots
Autorzy:
Łuczak, J.
Bułka, B.
Powiązania:
https://bibliotekanauki.pl/articles/1427582.pdf
Data publikacji:
2012-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.10.-w
33.57.+c
73.23.-b
73.63.Kv
Opis:
We analyze influence of an external electric field on magnetic properties of a triple quantum dot system in a triangular and linear geometry. The system contains four electrons and is described by an extended Hubbard model which includes electron correlations and exchange processes. The electric field leads to splitting of energy levels (the Stark effect) and to transition between the singlet and triplet states.
Źródło:
Acta Physica Polonica A; 2012, 121, 5-6; 1195-1197
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Relation of Gutzwiller Variational State with Matrix Model
Autorzy:
Koper, A.
Mucha, M.
Powiązania:
https://bibliotekanauki.pl/articles/1955829.pdf
Data publikacji:
1997-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
02.70.Lq
02.50.Ng
11.10.-z
71.27.+a
71.10.-w
Opis:
It is shown that mean values of electron operators in variational Gutzwiller state are equal to mean values of corresponding classical quantities calculated by means of a hermitian matrix model. In cases with small number of electrons in the system this property enables exact calculation of the mean values. In case of large number of electrons a simple and effective Monte Carlo method is formulated (within matrix model).
Źródło:
Acta Physica Polonica A; 1997, 91, 2; 391-394
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Quantum Dot Properties in a Strong Magnetic Field
Autorzy:
Matulis, A.
Anisimovas, E.
Powiązania:
https://bibliotekanauki.pl/articles/2038087.pdf
Data publikacji:
2004-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.21.La
71.10.-w
75.75.+a
Opis:
We present a quasiclassical approach to few-electron quantum dots in strong magnetic fields based on the notion of a collectively rotating Wigner molecule. A quasiclassical many-particle wave function is derived and illustrated by its application to a two-electron quantum dot. In particular, we calculate the density-current correlation function (conditional current) and show that the Wigner crystal in high magnetic fields may be visualized as an ordered system of current vortices.
Źródło:
Acta Physica Polonica A; 2004, 105, 6; 529-536
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On Stability of Frustrated Quantum Magnetic States in Fullerenes
Autorzy:
Koper, A.
Mucha, M.
Powiązania:
https://bibliotekanauki.pl/articles/1964713.pdf
Data publikacji:
1997-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.70.Wz
61.46.+w
71.10.-w
71.27.+a
75.10.Jm
02.50.Ng
02.70.Lq
Opis:
Gutzwiller variational ground states |Φ$\text{}^{G}$⟩ of π electrons, described by single-band half-filling Hubbard model, were determined for the molecules C$\text{}_{60}$ and C$\text{}_{70}$ and their energies and magnetic properties investigated. To construct these states two types of trial functions were used: generalized spin-density wave |Φ$\text{}_{SD}$⟩ and tight-binding wave |Φ$\text{}_{ΤΒ}$⟩. Our results evidently show that the Gutzwiller state |Φ$\text{}_{TΒ}^{G}$⟩ determined by means of function |Φ$\text{}_{ΤΒ}$⟩ has lower energy than the other investigated variational states |Φ$\text{}_{SD}^{G}$⟩. Mean values of the operators in the Gutzwiller states were calculated using Monte Carlo method.
Źródło:
Acta Physica Polonica A; 1997, 92, 2; 395-398
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Off-Diagonal Nonmagnetic Disorder in s- and d-Wave Superconductors
Autorzy:
Michalik, M.
Wysokiński, K. I.
Powiązania:
https://bibliotekanauki.pl/articles/2046788.pdf
Data publikacji:
2006-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.10.-w
71.23.-k
74.20.-z
Opis:
The previously developed approach to study off-diagonal disorder has been extended and applied to both s- and d-wave superconductors. The derived equations allow the self-consistent solution of the problem. For a special case of negative U centres embedded in non-superconducting host we have calculated their critical concentration for the appearance of superconductivity and found it equal to≈0.4. For x>x$\text{}_{cr}$ the order parameter continuously increases to its maximal value at x=1.
Źródło:
Acta Physica Polonica A; 2006, 109, 4-5; 623-626
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Novel Excitation-Density Dependence in Strongly Spin-Charge Coupled System
Autorzy:
Ohara, J.
Kanamori, Y.
Ishihara, S.
Powiązania:
https://bibliotekanauki.pl/articles/1490003.pdf
Data publikacji:
2012-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.30.+h
71.10.-w
78.47.J-
78.20.Bh
Opis:
Photoinduced spin-charge dynamics in strongly correlated electron systems is studied based on an extended double-exchange model. Solving a time-dependent Schrödinger equation with the Lanczos method, we trace the process of photoinduced melting of an antiferromagnetic charge order and analyze the excitation-density dependence on that. In the case of low density photoexcitation, both charge and spin orders are melted by photocarrier doping. This is interpreted with a conventional double-exchange mechanism. In the case of high density photoexcitation, however, the charge order is melted. The antiferromagnetic spin order is transiently weakened but after turnoff of the photoirradiation it recovers. This phenomenon strikingly differs from the weak photoexcitation case.
Źródło:
Acta Physica Polonica A; 2012, 121, 2; 355-358
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Non-Local Electron-Positron Enhancement Factors in Solids
Autorzy:
Rubaszek, A.
Szotek, Z.
Temmerman, W.
Powiązania:
https://bibliotekanauki.pl/articles/2008184.pdf
Data publikacji:
1999-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
71.10.-w
71.60.+z
Opis:
Non-local electron-positron correlation effects in solids are studied. The weighted density approximation is applied to calculations of the non-local electron-positron correlation functions. The calculated weighted density approximation electron-positron enhancement factors for the core electrons are compared with those obtained within the local density approximation. Also, differences in the electron-positron enhancement factors due to the s, p, d and f angular momentum channels of the electron charge density are studied. The formalism is applied to ab initio calculations of positron lifetimes in a variety of metals and silicon. The influence of various approximations to the electron-positron interaction on the positron lifetimes is also presented. The weighted density approximation results are compared to those calculated within the local density approximation, the recent generalized gradient approximation and with experimental data.
Źródło:
Acta Physica Polonica A; 1999, 95, 4; 652-658
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Next-Nearest-Neighbor Hopping in the Falicov-Kimball Model
Autorzy:
Czajka, K.
Maśka, M. M.
Powiązania:
https://bibliotekanauki.pl/articles/2046727.pdf
Data publikacji:
2006-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.10.-w
71.10.Fd
Opis:
Results of Monte Carlo simulations for the spinless Falicov-Kimball model with the next-nearest-neighbor hopping are presented. We find the critical value of the next-nearest-neighbor hopping integral, below which the low temperature configuration of the localized particles is the same as in the presence of only the nearest-neighbor hopping. Beyond this critical value the localized particles form horizontal or vertical stripes.
Źródło:
Acta Physica Polonica A; 2006, 109, 4-5; 465-469
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mapping of the DFT Spin Configuration Energies of Cr8Cd Molecular Ring onto the Energy Structure of Falicov-Kimball Model
Autorzy:
Wojciechowski, M.
Brzostowski, B.
Lemański, R.
Kamieniarz, G.
Powiązania:
https://bibliotekanauki.pl/articles/1386266.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Xx
71.15.Mb
73.22.-f
75.30.Et
31.15.E-
71.10.-w
Opis:
A comprehensive study of electronic and magnetic properties of a recently synthesized nonametalic chromium-based heteronuclear molecule Cr₈CdF₉(O₂C-C(CH₃)₃)₁₈ is presented, using DFT and Falicov-Kimball (FK) model approach. The magnetic moments are calculated and the spin charge density map is discussed. The exchange coupling parameters between transition metals ions are extracted, taking into account all the nonequivalent spin configurations. It is demonstrated that the energies of the spin configurations can be reproduced by the FK model with a set of parameters consistent with that for the parent Cr8 molecule. For molecular ring considered, the ground state corresponds to the antiferromagnetic configuration and the ferromagnetic configuration yields the highest energy.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 410-412
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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