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Wyszukujesz frazę "Djafari Rouhani, B." wg kryterium: Autor


Wyświetlanie 1-6 z 6
Tytuł:
Resonant Phonons in Adsorbed Slabs
Autorzy:
Dobrzynski, L.
Akjouj, A.
Syla, B.
Djafari-Rouhani, B.
Powiązania:
https://bibliotekanauki.pl/articles/1892256.pdf
Data publikacji:
1992-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.60.-p
Opis:
Resonant phonons, sometimes also called leaky waves, are phonons associated with a crystal defect, a surface, an adsorbed layer and whose frequencies fall inside the bulk crystal band. Such resonant phonons were studied experimentally and theoretically before for clean surfaces and for adsorbed monolayers. We present here a study of resonant phonons associated with the adsorption of a slab of L monolayers on a substrate. With the help of a simple atomic model, we obtained a closed form expression giving the variation of the transverse phonon density of states associated with the adsorption of the slab. An application which qualitatively simulates the adsorption of L monolayers of Ge on Si shows the existence of well-defined resonant phonons within the bulk acoustic band of the substrate.
Źródło:
Acta Physica Polonica A; 1992, 81, 1; 85-90
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the Magnon Spectrum of Antiferromagnetically Aligned Bilayer Films
Autorzy:
Puszkarski, H.
Kołodziejczak, B.
Akjouj, A.
Djafari-Rouhani, B.
Dobrzynski, L.
Powiązania:
https://bibliotekanauki.pl/articles/1929330.pdf
Data publikacji:
1993-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.70.-i
75.50.Ee
Opis:
We deal with spin-wave propagation in two antiferromagnetically aligned sublayers forming one bilayer film owing to the antiferromagnetic exchange coupling assumed to exist at the film interface. We get the following picture: as the spin wave traverses the interface, the creation of a spin-reversal in the one sublayer becomes an annihilation in the other sublayer. This feature is expressed by the non-conventional type of normalization condition of the spin-wave amplitudes.
Źródło:
Acta Physica Polonica A; 1993, 83, 5; 677-683
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Resonant Phonons in Adsorbates
Autorzy:
Dobrzynski, L.
Djafari Rouhani, B.
Zieliński, P.
Akjouj, A.
Sylla, B.
Oumghar, E.
Powiązania:
https://bibliotekanauki.pl/articles/1943987.pdf
Data publikacji:
1996-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.35.JS
68.45.-v
Opis:
After a brief review on surface phonons, we focus on resonant phonons in adsorbed thin layers. Such resonances may in general be understood within the substrate bulk band as thin layer modes shiften and broaden by the interaction with the substrate phonons. These resonant phonons appear as well-defined peaks in the phonon density of states. Their experimental study started recently by Helium atom scattering spectroscopy. This review will end by a prospective revue done mostly after the presentation of two unpublished results. First the slab resonant phonons may almost be confined in the surface slab even for frequencies falling within the bulk phonon band, if the surface slab is separated from the substrate by a buffer layer. The other prospective unpublished result deals with a model system in which the propagating phonons reach a space point from which they can continue to propagate through two different finite in space channels before reaching again a homogeneous uniform path. Such a system exhibits some frequencies for which the transmission factor vanishes. This phenomenon is related to the resonances associated with the finite additional path offered to the propagation of the phonons.
Źródło:
Acta Physica Polonica A; 1996, 89, 2; 139-144
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Brillouin Zone Mapping of the Existence Conditions for Interface Bilayer Spin-Waves. Effects of the Configuration of the Film Magnetization
Autorzy:
Puszkarski, H.
Józefowicz, R.
Kołodziejczak, B.
Akjouj, A.
Djafari-Rouhani, B.
Dobrzynski, L.
Powiązania:
https://bibliotekanauki.pl/articles/1945427.pdf
Data publikacji:
1996-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Ds
75.70.Cn
Opis:
For the two interface cubic cuts: sc(110) and sc(111) we consider the existence regions of interface spin-waves of a ferromagnetic bilayer film on the two-dimensional Brillouin zone as to their size and shape versus the respective interface related parameters (interface exchange coupling and intrinsic interface anisotropy) applying the approximation of a very thick bilayer film and the method of Brillouin zone mapping (the three (100) interface cubic orientations have been dealt with earlier [Phys. Rev. B 51, 16008 (1995)]). Of particular interest to us still remains the emergence of interface spin-waves induced by varying dynamic quantities such as the in-plane propagation wave vector k$\text{}_{∥}$. Moreover, in our present investigation, we put especial emphasis on the effect exerted on the Brillouin zone mapping by varying (in the plane perpendicular to the film) the configuration angle of the film magnetization with respect to the film normal. We predict the existence of (at the most two) critical angles $\text{}_{c}$ at which the interface spin-waves emerge. These critical angles are functions of the in-plane wave vector k$\text{}_{∥}$ of interface spin-wave propagation along the interface. Finally, we discuss the effects due to the presence of critical angles with a view to their exploitation in experimental measurements.
Źródło:
Acta Physica Polonica A; 1996, 89, 5-6; 675-688
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electronic Energies of Interaction of Point Defects with Interfaces and Grain Boundaries
Autorzy:
Vasseur, J.O.
Deymier, P.A.
Akjouj, A.
Dobrzynski, L.
Djafari-Rouhani, B.
Powiązania:
https://bibliotekanauki.pl/articles/1892209.pdf
Data publikacji:
1992-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.-b
73.40.-c
61.70.Yq
68.35.Dv
Opis:
The electronic energies of interaction of a point defect with interfaces and grain boundaries are calculated, as a function of the distance x$\text{}_{03}$ between the point defect and the corresponding planar defect. These interaction energies are shown to have the same type of oscillations as the corresponding local electronic densities. Therefore the electronic interactions more significantly affect the energy of segregation of point defects towards interfaces when x$\text{}_{03}$ is in the near vicinity of these interfaces, while at large distances the contribution of elastic interactions can dominate.
Źródło:
Acta Physica Polonica A; 1992, 81, 1; 39-46
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Elastic Vibrations of Planar and Deterministic Rough Surfaces
Autorzy:
Djafari Rouhani, B.
Khelif, A.
El Boudouti, E. H.
Akjouj, A.
Dobrzynski, L.
Powiązania:
https://bibliotekanauki.pl/articles/1943986.pdf
Data publikacji:
1996-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.35.Ja
68.45.Kg
Opis:
We present a few recent or new theoretical results about surface acoustic localized and resonant modes associated with planar or deterministic rough surfaces. The following composite systems are considered: one or two adlayers deposited on a semi-infinite substrate and wires or grooves integrated near a planar surface. The surface modes can be obtained as well-defined features of the density of states resulting from a calculation of the Green functions in these heterostructures. In this work, the materials are described in the framework of the elasticity theory.
Źródło:
Acta Physica Polonica A; 1996, 89, 2; 129-137
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-6 z 6

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