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Wyszukujesz frazę "Bak, M" wg kryterium: Autor


Tytuł:
The Fock Term in the Charge Ordered Phase of the t-W Model
Autorzy:
Bak, M.
Powiązania:
https://bibliotekanauki.pl/articles/1427073.pdf
Data publikacji:
2012-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.45.Lr
71.10.Fd
71.27.+a
71.30.+h
Opis:
The paper shows the importance of retaining Hartree and Fock terms, appearing after mean-field decoupling, in the treatment of charge ordered phase of the t-W model, with implications to extended Hubbard model.
Źródło:
Acta Physica Polonica A; 2012, 121, 5-6; 1085-1088
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
S-Wave Bound- and Resonant States of Two Fermions in Simple Cubic Lattice
Autorzy:
Bak, M.
Powiązania:
https://bibliotekanauki.pl/articles/1431271.pdf
Data publikacji:
2012-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
02.30.Gp
03.65.Ge
31.15.ac
71.10.Fd
Opis:
Resonant two-electron states are examined in attractive Hubbard model on simple cubic lattice and exact formula for scattering cross section in the limit of low density (empty lattice) is calculated. S-wave pair is considered by means of lattice Green functions (LGF). Analytical form of these functions found by Joyce is used facilitating calculations, which were greatly hindered before by the necessity of using LGF's tabulated values. It is found that the actual peak of scattering cross-section is formed on the lower band boundary in discrepancy with formulae of the theory of scattering in solids.
Źródło:
Acta Physica Polonica A; 2012, 121, 4; 808-811
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Resonant Two-Electron Pairs in a Simple Cubic Lattice
Autorzy:
Bak, M.
Powiązania:
https://bibliotekanauki.pl/articles/1374452.pdf
Data publikacji:
2014-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.10.Fd
31.15.xh
71.10.Li
71.55.-i
03.65.Ge
02.30.Zz
Opis:
The properties of resonant two-electron pairs are examined in three-dimensional simple cubic extended Hubbard tUW model, in s- and d- symmetry channels, in the limit of empty lattice. Lattice Green function technique is applied to calculate the scattering amplitude by means of matrix for any energy in the band on ΓR line within the Brillouin zone. The analysis shows the persistence of resonant states even for Coulomb interactions so weak that the equation for the resonant states is not formally fulfilled. The difference in behavior of resonances controlled by on-site and intersite Coulomb interactions is found. The ranges of applicability of approximate formula for the actual position of resonant peak and its width are shown.
Źródło:
Acta Physica Polonica A; 2014, 126, 4a; A-63-A-69
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mixed Phase and Bound States in the Phase Diagram of the Extended Hubbard Model
Autorzy:
Bąk, M.
Powiązania:
https://bibliotekanauki.pl/articles/1857970.pdf
Data publikacji:
2004-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.10.Fd
71.10.Hf
71.27.+a
Opis:
The paper examines part of the ground state diagram of the extended Hubbard model, with the on-site attraction U<0 and intersite repulsion W>0 in the presence of charge density waves, superconducting andη-superconducting order parameters. We show the possibility of the stabilization of the mixed state, with all three nonzero order parameters, in the model with nearest neighbor interactions. The other result of the paper is application of the exact solution of the Schrödinger equation for the two-electron bound state, as an additional bound for the phase diagram of the model, resulting in the partial suppression of the superconducting state of the s-wave symmetry, in favor of the normal state phase.
Źródło:
Acta Physica Polonica A; 2004, 106, 5; 637-646
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Lattice Green Functions on a Two-Dimensional Rectangular Lattice with Next-Nearest Neighbor Interaction
Autorzy:
Bak, M.
Powiązania:
https://bibliotekanauki.pl/articles/1537144.pdf
Data publikacji:
2010-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
02.30.Gp
02.30.Uu
02.60.Nm
71.15.-m
02.70.Hm
71.10.Fd
Opis:
The analytic formula for the on-site Green function on the two-dimensional rectangular lattice is shown for arbitrary energy, both within the band (complex Green function) and outside the band (real Green function), expressed by means of elliptic integrals. The recursion formulae enabling calculation of the Green functions on other lattice sites are shown.
Źródło:
Acta Physica Polonica A; 2010, 118, 2; 386-388
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Properties of the Bound States on a Hexagonal Lattice
Autorzy:
Bak, M.
Powiązania:
https://bibliotekanauki.pl/articles/2047341.pdf
Data publikacji:
2007-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.10.Fd
74.20.Rp
71.27.+a
71.10.Hf
Opis:
Two electrons on a lattice pose an interesting problem which can be solved exactly. When the effective interactions are strong enough, the bound states are formed. The properties of such bound pairs in an extended Hubbard model are examined for both signs of nearest neighbor hopping integral t. The stabilization of s*-wave pairing is found for t<0 and of f-wave for t>0. Phase diagrams for the existence of none, one or two s*-wave solutions are calculated.
Źródło:
Acta Physica Polonica A; 2007, 111, 5; 781-789
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Universal Relations in the Attractive Hubbard Model with Next-Nearest Neighbor Hopping
Autorzy:
Bak, M.
Powiązania:
https://bibliotekanauki.pl/articles/2046748.pdf
Data publikacji:
2006-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Fy
71.10.Fd
74.20.Fg
71.27.+a
72.10.-d
Opis:
Recently a new universal relation between superfluid densityρ$\text{}_{s}$ andσ$\text{}_{dc}$T$\text{}_{c}$, where σ$\text{}_{dc}$ is direct current conductivity and T$\text{}_{c}$ - superconducting critical temperature, was found by Homes et al. (Nature 430, 539 (2004)). The theoretical derivation of the relation based on BCS theory is correct only qualitatively. In the present paper this relation is calculated theoretically, using Hartree-Fock approximation and second-order perturbation theory. It is found that although correct qualitatively, quantitatively the results are too small. Inclusion of the second neighbor hopping improves the results.
Źródło:
Acta Physica Polonica A; 2006, 109, 4-5; 565-568
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Critical Values for Electron Pairing in t-U-J-V and t-J-V Models
Autorzy:
Bak, M.
Powiązania:
https://bibliotekanauki.pl/articles/1812342.pdf
Data publikacji:
2008-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.20.-z
74.20.Fg
74.20.Rp
74.25.Dw
71.10.Fd
71.27.+a
Opis:
The critical values for pairing of s*- and d-wave symmetry are calculated within the t-U-J-V and the t-J-V models in renormalized mean field theory. It is shown that the first model yields the proper critical values in the low density limit while the other does not. Renormalized mean field theory strongly decreases the absolute value of (negative) critical values for larger electron densities.
Źródło:
Acta Physica Polonica A; 2008, 114, 1; 275-279
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effective Mass of Bound and Resonant Two-Electron Pairs in a Simple Cubic Lattice
Autorzy:
Bak, M.
Powiązania:
https://bibliotekanauki.pl/articles/1385287.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
03.65.Ge
37.10.Jk
Opis:
Effective masses m* of bound 2-electron pairs on a simple cubic lattice were investigated within tUWJ model within symmetry channels. Linear increase of m* with |W| for intersite pairs and nonlinear behavior and sign change of m* in case of pairs with on-site component were found. |m*| turned out to be larger than twice free electron mass.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 290-292
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bound States of Fermions on 2d Lattice in a Dilute Limit
Autorzy:
Bąk, M.
Micnas, R.
Powiązania:
https://bibliotekanauki.pl/articles/2012890.pdf
Data publikacji:
2000-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.20.-z
03.65.Ge
71.10.Fd
Opis:
We examine extended bound states in a dilute limit of the extended Hubbard model on the two-dimensional square lattice. By solving exactly the two-body problem we have determined the binding energies, mobilities, and dispersion curves across the Brillouin zone for bound states of various symmetries. It turns out that the d-wave pairing is strongly favored by the nnn hopping and the intersite local pairs can have small effective masses, even in the case of strong binding.We have also found a possibility of extended s-$d_{x^{2}-y^{2}}$ mixing of the bound states.
Źródło:
Acta Physica Polonica A; 2000, 97, 1; 209-212
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mixed State in t-U-J-V Model
Autorzy:
Tobijaszewska, B.
Bak, M.
Powiązania:
https://bibliotekanauki.pl/articles/1810406.pdf
Data publikacji:
2009-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.20.-z
74.20.Rp
74.25.Dw
71.10.Fd
71.27.+a
Opis:
The t-U-J-V model in the U → ∞ limit is treated by renormalized mean-field theory for arbitrary electron density. Superconductivity of s+id symmetry is found in the large parts of the phase diagram. Calculations also show a possibility of phase separation.
Źródło:
Acta Physica Polonica A; 2009, 115, 1; 135-137
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reinforcement of Elastic Polymer Matrix Filled with Ultrafine Particles
Autorzy:
Kryszewski, M.
Bąk, G. W.
Powiązania:
https://bibliotekanauki.pl/articles/1968469.pdf
Data publikacji:
1997-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
62.20.Dc
81.20.Ti
Opis:
The nanofiller of noble metal may modify the properties of the polymer- noble metal composite even if the concentration of the metal nanoparticles is very low. The aim of this paper is to study the influence of colloidal particles in nanocomposites. For our studies we have selected polymethyl methacrylate-palladium nanocomposite. It is shown that the effective radius of the immobilised matrix environment is much greater than the radius of the palladium particles. Due to the binding of the matrix polymer and the palladium surface some volume of the surrounding matrix becomes immobilised giving rise to the effective increase in the size of the palladium filler. The analysis of a few models of nanocomposites used for interpretation of the mechanical properties has also been presented.
Źródło:
Acta Physica Polonica A; 1997, 92, 6; 1163-1167
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamics of the Molecules in Solid Phases of Few Chosen Schiff Bases Compounds
Autorzy:
Bąk, A.
Massalska-Arodź, M.
Powiązania:
https://bibliotekanauki.pl/articles/2037298.pdf
Data publikacji:
2004-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.Md
77.22.Gm
Opis:
The dielectric relaxation processes observed in solid phases of MBBA, OH-MBBA, and EBBA belonging to the homologous series of the Schiff bases are discussed. The data are compared with the results completed by the present authors for EBPA compound. The uniform interpretation of the temperature changes of relaxation for all mentioned compounds is proposed.
Źródło:
Acta Physica Polonica A; 2004, 105, 5; 467-474
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magneto-Optical Characteristics of Human Serum
Autorzy:
Surma, M.
Bućko, J.
Bąk, G.
Ciszek, M.
Powiązania:
https://bibliotekanauki.pl/articles/2014394.pdf
Data publikacji:
2000-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.25.Lc
78.20.Ek
78.20.Ls
Opis:
A study of magneto-optical circular birefringence of human serum from healthy subjects and cancer patients was performed. Significant differences in the magnetic field induced change of the natural optical activity of serum from healthy blood donors and neoplasmic patients were noted. The natural optical activity of blood is positive, irrespective of the donor health status, whereas the magnetic field induced (B > 10T) change in the natural optical activity of the serum from cancer patients is negative while that from healthy donors is positive. The value and sign of the characteristic magneto-optical marker of human serum was discovered in a study of the influence of very high magnetic fields on chiral media and interpreted on the basis of the recent developments in the theory of magnetic field induced optical circular birefringence in the media revealing natural optical activity. The blood serum is a chiral medium.
Źródło:
Acta Physica Polonica A; 2000, 98, 5; 533-542
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Molecular Dynamics of n-p-(Ethoxybenzylidene) P-Propylaniline in Nematic and Solid Phases as Studied by Dielectric Relaxation Spectroscopy
Autorzy:
Bąk, A.
Massalska-Arodź, M.
Urban, S.
Powiązania:
https://bibliotekanauki.pl/articles/2012951.pdf
Data publikacji:
2000-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.Md
77.22.Gm
Opis:
The complex dielectric permittivity ε*(ν,T) = ε'(ν,T) - iε''(ν,T) of n-p-(ethoxybenzylidene) p'-propylaniline has been measured in the frequency range from 1 Hz to 13 MHz and temperature range from 360 K to 180 K on heating and on cooling the sample. Dielectric relaxations have been found in nematic and solid phases. A detailed analysis of the observed processes has been performed and the parameters describing molecular dynamics have been evaluated. The comparison of results with those obtained for the other Schiff bases is discussed.
Źródło:
Acta Physica Polonica A; 2000, 97, 2; 323-330
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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