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Wyszukujesz frazę "Schmidt, W." wg kryterium: Wszystkie pola


Wyświetlanie 1-4 z 4
Tytuł:
Exchange Coupling of Magnetic Multilayers in Spin-Polarized Jellium
Autorzy:
Schmidt, W.
Powiązania:
https://bibliotekanauki.pl/articles/1955446.pdf
Data publikacji:
1997-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.20.-r
75.70.-i
Opis:
The bilinear and biquadratic coupling between two metallic layers separated by a nonmagnetic metal spacer are studied. The paper contains analytical formulae for the coupling which are obtained from the energy potential of the spin-polarized electron gas. The formulae for the coupling are obtained in the framework of the Hohenberg-Kohn formalism of the density functional theory and variables of the coupling are the electron density and the spin polarization of the magnetic multilayer.
Źródło:
Acta Physica Polonica A; 1997, 91, 2; 265-268
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Exchange Stiffness Parameter and Magnetization in Pseudopotential Calculations
Autorzy:
Schmidt, W.
Powiązania:
https://bibliotekanauki.pl/articles/2013986.pdf
Data publikacji:
2000-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.15.Mb
71.15.Hx
75.30.Et
Opis:
We study low temperature magnetic properties of transition metals. The ground state spontaneous magnetization is calculated in a pseudopotential approximation. In the calculations, the core electronic orbitals are approximated by asymptotic expressions. The magnetizations are calculated for uniform spin densities of valence (chemically active) electrons and in the Lindhard approximation. Our calculations of the Bloch wall parameter and the magnon stiffness constant are based on a study of ferromagnetic and paramagnetic phases. A simple Bragg-Williams approximation between energy of spin polarization and the time-average of the spin moment per atom determines the "exchange coupling" (Heisenberg-like) for spin-polarized nearest neighbour Wigner-Seitz cells. Ab initio numerical results of the spontaneous magnetization, the Bloch wall parameter, and the magnon stiffness constant are obtained for Fe, Co, and Ni.
Źródło:
Acta Physica Polonica A; 2000, 97, 5; 967-970
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Spin-Wave Stiffness within Density Functional Theory and the Ginzburg-Landau Functional
Autorzy:
Schmidt, W.
Powiązania:
https://bibliotekanauki.pl/articles/2014458.pdf
Data publikacji:
2000-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Et
71.15.Mb
Opis:
The stiffness constant of the stationary spin excitation is calculated employing density functional theory and the phenomenological Ginzburg-Landau energy functional in a site form. The exchange parameter of the magnetic functional is estimated within the framework of the nearest neighbours intermolecular interaction and the energy gain of non-magnetic state per atom. The stiffness constant of Fe, Co, and Ni metals is found based on the energies of spin polarization calculated numerically in the local spin density approximation by Moruzzi et al. as well as by Kübler. The calculated stiffness constants are compared with other theoretical calculations and experimental data.
Źródło:
Acta Physica Polonica A; 2000, 98, 5; 625-628
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nanostructural Superconducting Materials for Fault Current Limiters and Cryogenic Electrical Machines
Autorzy:
Prikhna, T.
Gawalek, W.
Savchuk, Ya.
Sergienko, N.
Moshchil, V.
Sokolovsky, V.
Vajda, J.
Tkach, V.
Karau, F.
Weber, H.
Eisterer, M.
Joulain, A.
Rabier, J.
Chaud, X.
Wendt, M.
Dellith, J.
Danilenko, N.
Habisreuther, T.
Dub, S.
Meerovich, V.
Litzkendorf, D.
Nagorny, P.
Kovalev, L.
Schmidt, Ch.
Melnikov, V.
Shapovalov, A.
Kozyrev, A.
Sverdun, V.
Kosa, J.
Vlasenko, A.
Powiązania:
https://bibliotekanauki.pl/articles/1549637.pdf
Data publikacji:
2010-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Sv
74.81.Bd
74.70.Ad
74.78.Na
74.62.Fj
74.25.Ld
74.62.Dh
74.25.Ha
Opis:
Materials of the Y-Ba-Cu-O (melt-textured $YBa_{2}Cu_{3}O_{7-δ}$-based materials or MT-YBCO) and Mg-B-O ($MgB_{2}$-based materials) systems with high superconducting performance, which can be attained due to the formation of regularly distributed nanostructural defects and inhomogeneities in their structure can be effectively used in cryogenic technique, in particular in fault current limiters and electrical machines (electromotors, generators, pumps for liquid gases, etc.). The developed processes of high-temperature (900-800°C) oxygenation under elevated pressure (16 MPa) of MT-YBCO and high-pressure (2 GPa) synthesis of $MgB_{2}$-based materials allowed us to attain high superconductive (critical current densities, upper critical fields, fields of irreversibility, trapped magnetic fields) and mechanical (hardness, fracture toughness, Young modulus) characteristics. It has been shown that the effect of materials properties improvement in the case of MT-YBCO was attained due to the formation of high twin density (20-22 $μm^{-1}$), prevention of macrocracking and reduction (by a factor of 4.5) of microcrack density, and in the case of $MgB_{2}$-based materials due to the formation of oxygen-enriched as compared to the matrix phase fine-dispersed Mg-B-O inhomogeneities as well as inclusions of higher borides with near-$MgB_{12}$ stoichiometry in the Mg-B-O matrix (with 15-37 nm average grain sizes). The possibility is shown to obtain the rather high $T_{c}$ (37 K) and critical current densities in materials with $MgB_{12}$ matrix (with 95% of shielding fraction as calculated from the resistant curve).
Źródło:
Acta Physica Polonica A; 2010, 117, 1; 7-14
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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