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Wyszukujesz frazę "Gorski, G." wg kryterium: Autor


Wyświetlanie 1-5 z 5
Tytuł:
Ferromagnetic Systems with Hopping Interaction
Autorzy:
Górski, G.
Mizia, J.
Powiązania:
https://bibliotekanauki.pl/articles/1537008.pdf
Data publikacji:
2010-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.10.Fd
75.10.Lp
Opis:
We analyze the influence of hopping interaction on magnetic ordering. Scattering scheme of the Hubbard III approximation with included inter-site kinetic electron-electron correlation is used. The hopping interaction and inter-site correlation lead to two spin dependent effects: the band width correction and the band-shift correction. The band-shift correction factor causes an exchange splitting between the spin-up and spin-down spectrum, and its role is similar to the exchange interaction in the classic Stoner model. The spin dependent band width correction enhanced strongly by the inter-site kinetic correlation lowers the kinetic energy of electrons by decreasing the majority spin band width for some electron occupations with respect to the minority spin band width. The results show that in the case of the symmetrical density of states there is only ferromagnetic enhancement. For the strongly asymmetrical density of states there is a ferromagnetic transition.
Źródło:
Acta Physica Polonica A; 2010, 118, 2; 336-339
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Phase Separation near Half-Filling Point in Superconducting Compounds
Autorzy:
Kucab, K.
Górski, G.
Mizia, J.
Powiązania:
https://bibliotekanauki.pl/articles/1374052.pdf
Data publikacji:
2014-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.10.Fd
74.20.-z
75.10.Lp
Opis:
We present the model of superconducting ceramics using the single band extended Hubbard Hamiltonian. We investigate the simultaneous presence of antiferromagnetism and d-wave superconductivity in the coherent potential approximation applied to the on-site Coulomb repulsion U. We consider the hopping interaction, Δt, the inter-site charge-charge interaction, V (creating superconductivity), and the single site Hund type exchange interaction, $F_\text{in}$ (creating antiferromagnetism). The influence of these interactions on the separation of superconducting and antiferromagnetic phases near the half-filling point is investigated. Results are compared with the experimental data for YBaCuO and NdCeCuO compounds.
Źródło:
Acta Physica Polonica A; 2014, 126, 4a; A-104-A-106
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Band Magnetism with Inter-Site Correlations and Interactions
Autorzy:
Mizia, J.
Górski, G.
Kucab, K.
Powiązania:
https://bibliotekanauki.pl/articles/1374337.pdf
Data publikacji:
2014-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.10.Fd
75.10.Lp
75.50.Cc
Opis:
We introduce the Hamiltonian to describe narrow band electrons. The physics of driving forces towards ferromagnetism is re-examined. Using different approximations it has been shown that the magnetic moments created by inter-site interaction and inter-site kinetic correlation decrease quickly with temperature. As a result of these interactions and the realistic density of states the Curie temperatures calculated after fitting magnetic moments to their low temperature values are realistic. In the past the Curie temperatures calculated using only the on-site interaction were much higher than the experimental temperatures.
Źródło:
Acta Physica Polonica A; 2014, 126, 4a; A-30-A-31
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Coexistence of Ferromagnetism with Spin Triplet Superconductivity
Autorzy:
Górski, G.
Kucab, K.
Mizia, J.
Powiązania:
https://bibliotekanauki.pl/articles/1810408.pdf
Data publikacji:
2009-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.10.Fd
74.20.-z
75.10.Lp
Opis:
The experimental results for $ZrZn_2$, URhGe, and in some pressure ranges also for $UGe_2$, showed that the ferromagnetic superconductors are weak itinerant ferromagnets. Guided by these results we describe the phenomenon of coexistence between equal spin triplet pairing superconductivity and ferromagnetism using the extended Stoner model, which includes in Hamiltonian the on-site Coulomb interaction, U, and occupation dependent hopping integral. We use the Hartree-Fock approximation and the Green functions technique. In the Hartree-Fock approximation the on-site Coulomb interaction plays the role of the on-site exchange (Hund's) field. All inter-site interactions will have included the inter-site kinetic correlation, 〈$c_{iσ}^{+}c_{jσ}$〉, within the Hartree-Fock approximation. We introduce the pressure-dependence to the hopping integral. Numerical results are compared with experimental data for $ZrZn_2$. The kinetic correlation creates the superconductivity without help of negative values of the Coulomb interactions. The model can explain stimulation of triplet superconductivity by the weak itinerant ferromagnetism. This effect was observed experimentally in $ZrZn_2$. Numerical analysis also confirms the experimental effect of decrease in critical temperatures (Curie and superconducting) with increasing external pressure.
Źródło:
Acta Physica Polonica A; 2009, 115, 1; 141-143
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modified Equation of Motion Approach for Ferromagnetic Systems
Autorzy:
Górski, G.
Mizia, J.
Kucab, K.
Powiązania:
https://bibliotekanauki.pl/articles/1384824.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.10.Fd
75.10.Lp
75.30.Kz
Opis:
The key problem in using the dynamical mean-field theory is finding the appropriate solution to the single impurity Anderson model. We use the modified equation of motion method based on differentiation over two time variables. In such approach we obtain correct description of the Kondo effect not only for systems symmetrical with respect to the half-filled point but also for the systems without symmetry in a half filled point and for broad range of electron concentrations like e.g. the ferromagnetic systems. For the reason of these advantages we investigate in this report dependence of the system magnetic moment on carrier concentration using our modified equation of motion method. We also analyze influence of asymmetric densities of states on ferromagnetic alignment. Our results are compared with dynamical mean-field theory-quantum Monte Carlo calculations and with Hubbard I and III approximations.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 207-209
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-5 z 5

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