Wyniki wyszukiwania - Biblioteka Nauki

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Spin-wave theory of spin-polarized electron energy loss spectroscopy (SPEELS) measurements in 5 ML Fe film deposited on W(110)

100%

Mamica S. , Puszkarski H.

Materials Science Poland

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2008

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tom Vol. 26, No. 4

981--993

EN

Detection of spin waves with higher wave vector values is now possible with spin-polarized electron energy loss spectroscopy (SPEELS), a method recently reported to have been applied for detecting spin waves in a range of wave vector values covering in principle the whole Brillouin zone. This paper presents a comparison of spin-wave spectra resulting from our theoretical investigations (within the model based on a bi-linear Hamiltonian expressed in second-quantization formalism) with the corresponding SPEELS results obtained recently for 5 ML Fe film deposited on W(110) [JMMM, 272-276, 2126 (2004)]. By considering the mixed bcc-fcc film structure we were able to explain the details of the reported SPEELS spectra, indicating the surface character of the modes associated with the observed peaks.

2

Ferromagnetic and spin wave resonances in thin layer of expanded austenite phase

100%

Typek J. , Guskos N. , Zolnierkiewicz G. , Berczynski P. , Guskos A. , Baranowska J. , Fryska S.

Materials Science Poland

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2014

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tom Vol. 32, No. 2

198—205

EN

Four samples of austenite coatings deposited by reactive magnetron sputtering on silicon substrate at four different temperatures and pressures were investigated by ferromagnetic resonance (FMR) method at room temperature. The expanded austenite phase S (gN) layers with thickness in the 160 – 273 nm range and concentration of magnetic atoms: 72 % Fe, 18 % Cr and 10 % Ni, were obtained. The coatings with nanometric size grains were strongly textured and grown mostly in [100] direction, perpendicular to the sample surface. Intense FMR spectra were recorded at various angles between the static magnetic field direction and the sample surface. A strong magnetic anisotropy of the main uniform FMR mode was observed and the effective magnetization 4πMe f f determined. Spin wave resonance (SWR) modes were observed in all investigated samples in out-of-plane geometry of the magnetic field. The resonance fields of SWR modes in our samples varied linearly with the spin wave mode number. The value of the effective magnon stiffness constant was determined assuming a parabolic shape of the magnetization variation across the sample thickness.

3

Spin Waves in Two and Three Dimensional Magnetic Materials

88%

Wijesinhe H. s. , Wijewardena Gamalath K. A. I. L.

International Letters of Chemistry, Physics and Astronomy

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2015

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tom Vol. 49

35--47

EN

The equations of motion for the dynamic properties of spin waves in three dimensions were obtained using Heisenberg model and solved for two and three dimensional lattices analytically up to an exponential operator representation. The second order Suzuki Trotter decomposition method was extended to incorporate second nearest interaction parameters into the numerical solution. Computer based simulations on systems in micro canonical ensembles in constant-energy states were used to check the applicability of this model for two dimensional lattice as well as three dimensional simple cubic and bcc lattices. In the magnon dispersion curves all or most of the spin wave components could be recognized as peaks in the dynamic structure factor presenting the variation of energy transfer with respect to momentum transfer of spin waves. Second order Suzuki Trotter algorithm used conserved the energy.

4

Heisenberg-type ferromagnetic films with a sandwich structure

75%

Kecer J. , Ilkovič V.

Open Physics

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2006

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tom 4

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nr 4

461-471

EN

Green’s function theory is applied to an alternating two-element multilayer ferromagnetic film. The Hamiltonian is based on the Heisenberg model with a second-order uniaxial single-ion anisotropy and with the interaction between the layer in the interfaces. Magnetization and the phase transition in such system are derived for several sets of material parameters.

5

Spin waves in one dimensional magnetic material

75%

Wijesinhe H. S. , Wijewardena G. K. A. I. L.

International Letters of Chemistry, Physics and Astronomy

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2015

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tom Vol. 47

24--39

EN

Using Heisenberg model, the equations of motion for the dynamic properties of spin waves in three dimensions were obtained and solved analytically up to an exponential operator representation. Second order Suzuki Trotter decomposition method with evolution operator solution was applied to obtain the numerical solutions by making it closer to real spin systems. Computer based simulations on systems in micro canonical ensembles in constant-energy states were used to check the applicability of this model for one dimensional lattice by investigating the occurrence, temperature dependence and spin-spin interaction dependence of the spin waves. A visualization technique was used to show the existence of many spin wave components below the Curie temperature of the system. In the magnon dispersion curves all or most of the spin wave components could be recognized as peaks in the dynamic structure factor. Energy conservation of the algorithm is also shown.

6

The scattering of light on sound waves in the hypersonic range of frequencies the directional sensitivity of Brillouin light scattering

63%

Błachowicz T.

Open Physics

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2003

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tom 1

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nr 1

153-178

EN

Brillouin spectroscopy of acoustic phonons in transparent crystals and nontransparent metallic Co/Cu superlattices is reviewed. The method presents a directional sensitivity of the experiment. This feature is useful in elastic constants measurements in crystals and analysis of in-plane anisotropies of hyper-sound and spin waves in superlattices. Results for the LiTaO3, LiNbO3, LiNbO3:Cu, SLGO, SLAO crystals are provided. Spin wave results for the Co/Cu superlattices are presented.