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Tytuł:
Parametric Amplification in Magnetized Nondegenerate Semiconducting Plasmas
Autorzy:
Jat, K. L.
Neogi, A.
Ghosh, S.
Powiązania:
https://bibliotekanauki.pl/articles/1887743.pdf
Data publikacji:
1991-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.65.Ky
72.20.Ht
73.50.Rb
78.20.Hp
Opis:
Using the straightforward coupled-mode theory, the parametric amplification is analytically investigated in magnetized piezoelectric as well as non-piezoelectric semiconductors. The origin of nonlinear interaction is taken to be in the second-order optical susceptibility χ$\text{}^{(2)}$ arising from the nonlinear induced current density. The threshold value of the pump electric field E$\text{}_{0th}$ is obtained for crystals. E$\text{}_{0th}$ is found to decrease with the rise in magnetic field and fall with the rise in scattering angle. Parametric gain constants are obtained for different situations of practical interest, i.e. (i) for piezoelectric coupling only g$\text{}_{p}$, (ii) for deformation potential coupling only g$\text{}_{d}$, (iii) for both the couplings g$\text{}_{b}$. Numerical investigations reveal that the magnetic field increases the gain. Maximum gains are obtained for backward scattered mode. g$\text{}_{d}$ is always found to be less than g$\text{}_{p}$ and g$\text{}_{b}$. It is also found that g$\text{}_{p}$ and g$\text{}_{b}$ both are identical up to k ≈ x 10$\text{}^{7}$m$\text{}^{-1}$ and for k ≥ 3 x 10$\text{}^{7}$m$\text{}^{-1}$, g$\text{}_{b}$ exceeds g$\text{}_{p}$.
Źródło:
Acta Physica Polonica A; 1991, 79, 6; 829-841
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Effect on Highly Cr-Substituted Manganite Nd$\text{}_{0.6}$C a$\text{}_{0.4}$(Mn$\text{}_{0.5}$Cr$\text{}_{0.5}$)O$\text{}_{3}$
Autorzy:
Gamari-Seale, H.
Troyanchuk, I. O.
Bushinsky, M. V.
Stefanopoulos, K. L.
Hernandez-Velasco, J.
Powiązania:
https://bibliotekanauki.pl/articles/2037098.pdf
Data publikacji:
2004
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.25.+z
75.30.Kz
75.47.Lx
Opis:
Neutron powder-diffraction experiments on the highly Cr-substituted manganite, Nd$\text{}_{0.6}$Ca$\text{}_{0.4}$(Mn$\text{}_{0.5}$Cr$\text{}_{0.5}$)O$\text{}_{3}$, at different temperatures and fields reveal that the structure retains the charge exchange-type of the parent compound, Nd$\text{}_{0.6}$Ca$\text{}_{0.4}$MnO$\text{}_{3}$. It is antiferromagnetic below 200 K and becomes a canted antiferromagnet below 50 K. The Mn and Cr form zig-zag ferromagnetic chains coupled antiferromagnetically in the ac-plane. These are stacked along the b-axis with opposite spins.
Źródło:
Acta Physica Polonica A; 2004, 105, 1-2; 81-86
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electronic Properties of InAs/GaAs Self-Assembled Quantum Dot Structures and Devices Studied by Photocurrent Spectroscopy
Autorzy:
Mowbray, D. J.
Fry, P. W.
Skolnick, M. S.
Itskevich, I. E.
Harris, L.
Ashmore, A. D.
Finley, J. J.
Wilson, L. R.
Schumacher, K. L.
Barker, J. A.
O'Reilly, E. P.
Al-Khafaji, M.
Cullis, A. G.
Hopkinson, M.
Clark, J. C.
Hill, G.
Powiązania:
https://bibliotekanauki.pl/articles/2014190.pdf
Data publikacji:
2000-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.66.Fd
73.61.Ey
73.50.Pz
42.55.Px
Opis:
The power of photocurrent spectroscopy to study the electronic properties of InAs/GaAs self-assembled quantum dots is described. From comparison of results from different samples it is shown that photocurrent provides a direct means to measure absorption spectra of quantum dots. Studies in high electric field enable the electron-hole vertical alignment to be determined. Most surprisingly this is found to be opposite to that predicted by all recent predictions. Comparison with theory shows that this can only be explained if the dots contain significant amounts of gallium, and have a severely truncated shape. The nature of the ground and excited state transitions, carrier escape mechanisms from dots, in-plane wave function anisotropies and the modal gain of a quantum dot laser are determined.
Źródło:
Acta Physica Polonica A; 2000, 98, 3; 279-293
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Conductivity Effects in Bi₂TeO₅ Single Crystals
Autorzy:
Agarkov, K.
Sadovskaya, L.
Powiązania:
https://bibliotekanauki.pl/articles/1031021.pdf
Data publikacji:
2018-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.20.Jv
Opis:
The current-voltage characteristics (I-V) of non-stoichiometric bismuth tellurite crystals were studied in a range of temperatures from 150°C to 350°C and fields up to 2.5 kV/cm with asymmetric contacts (In-Ga eutectic and Na₂SiO₃). The I-V curves and observed monopolar injection are described by the approximation of space charge limited currents. In the composition of 47% Bi₂O₃-53% TeO₂ electronic conduction is prevailed. In the composition 43% Bi₂O₃-57% TeO₂ the conductivity is contributed by electrons and holes. The spectrum of local states in the band gap of the studied crystals is quasicontinuous, which cannot be described by models of a discrete or exponential distribution.
Źródło:
Acta Physica Polonica A; 2018, 133, 4; 940-942
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of the Elaboration Conditions on the Structural, Morphological and Luminescence Properties of ZnO Nanopowders
Autorzy:
Arab, L.
Guergouri, K.
Powiązania:
https://bibliotekanauki.pl/articles/1401219.pdf
Data publikacji:
2015-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Dz
81.07.Wx
81.20.Fw
07.57.Ty
78.55.Qr
68.37.Hk
Opis:
Pure ZnO nanopowders were synthesized by the sol-gel method, which has several advantages, among which we include, achieving low temperature deposition and synthesis of new hybrid organo-mineral materials. The effect of the elaboration conditions (the elaboration concentrations ratio of precursors $(C_{Z}//C_{A})$, the gelling temperature $(T_g)$ and the gelling time $(t_g)$) on the structural, morphological and luminescence properties of ZnO nanopowders has been investigated. The chemical composition of the powders, determined by FTIR spectroscopy, indicate the exclusive presence of Zn-O bonds, as it is shown by the XRD spectra. The XRD results indicate also that the synthesized ZnO powder is a solid solution, crystallizing in pure würtzite structure with a minimum grain size of about 23 nm for the powders prepared using: $C_{Z}//C_{A}$=0.06%, $T_g$=130°C and $T_g$=4 h. The morphological aspect, given by the SEM images, revealed that the powders are made of sheets, consisting of small particles agglomerated together. The photoluminescence study of the ZnO powders shows spectra with luminescence peaks from green to ultraviolet light, the more intensive emission is connected to the peaks of the blue luminescence.
Źródło:
Acta Physica Polonica A; 2015, 127, 4; 940-942
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Full-Vectorial Description of the Light Guidance in Anisotropic Photonic Liquid Crystal Fibers
Autorzy:
Rutkowska, K.
Wei, L.
Powiązania:
https://bibliotekanauki.pl/articles/1418035.pdf
Data publikacji:
2012-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
02.60.Cb
02.70.Bf
42.25.Bs
42.70.Qs
42.81.Wg
42.70.Df
Opis:
In this paper we present our theoretical approach for the description of the light guidance in photonic liquid crystal fibers. In particular, we focus on the numerical methods allowing for a full implementation of the liquid crystals properties (i.e., including their optical anisotropy and molecular orientation), with a final target in characterizing photonic liquid crystal fibers with accessible computational effort. For this purpose suitable analytical formulae required for a full-vectorial description of the optical modes in photonic liquid crystal fibers have been derived. In addition, computational schemes allowing for numerical implementation of theoretical formulations (with the use of the finite-difference scheme) have been developed, validated and optimized. Their numerical convergence has been checked for different structures, as well as for different input parameters (e.g., grid-size). Obtained results have been compared to those analytically calculated, known from literature and/or got with use of commercial software. Moreover, the implemented schemes have been examined in accordance with experimental tests performed on the photonic liquid crystal fiber of interest.
Źródło:
Acta Physica Polonica A; 2012, 122, 5; 880-890
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New Graphical Interface to the MOSGRAF Suite
Autorzy:
Duraj, Ł.
Ruebenbauer, K.
Powiązania:
https://bibliotekanauki.pl/articles/1506654.pdf
Data publikacji:
2011-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.80.+y
07.05.Kf
Opis:
A contribution is devoted to the recent development of the MOSGRAF suite used to process Mössbauer data and to generate reference functions for the modern spectrometers of the MsAa-x (x=1, 2, 3, 4) family. Newly developed interface is designed for the Microsoft Windows-XP® or higher system of this class. However one can use some older system of this class as well provided some plug-ins are installed additionally. The lowest useable system is Microsoft Windows-98® - 32-bit edition. The new version of the MOSGRAF suite is compatible with 32-bit and 64-bit systems. MOSGRAF is fully compatible with MsAa-x spectrometers, however a powerful tool to convert ASCII data files from other spectrometers is provided. Data processing programs are compiled by the high efficiency Fortran-90 Lahey-Fujitsu® compiler. One of the most important new features is the ability to process velocity calibration data obtained by the new method based on the measurement of the time lapse between fringes of the Michelson-Morley interferometer.
Źródło:
Acta Physica Polonica A; 2011, 119, 1; 75-77
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Properties of Nanocrystalline Co/Ti and Co/Zr Multilayers
Autorzy:
Smardz, L.
Smardz, K.
Powiązania:
https://bibliotekanauki.pl/articles/2013147.pdf
Data publikacji:
2000-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.70.-i
75.30.Et
Opis:
It is shown that the Co sublayers grow in the soft magnetic nanocrystalline phase up to a critical thickness d≈3 and 2.8 nm for Co/Ti and Co/Zr MLs, respectively. The rapid decrease in the interlayer exchange coupling could be explained by its strong damping due to formation of a non-magnetic quasi-amorphous Co-Ti and Co-Zr alloy layer at the interfaces. The nanocrystalline 2.2 nm-Co/2 nm-Ti ML shows a weak 90° coupling near the transition zone from ferromagnetic to zero coupling.
Źródło:
Acta Physica Polonica A; 2000, 97, 3; 511-514
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Branching Ratio Measurements for Ge I and Ge II
Autorzy:
Bratasz, Ł.
Musioł, K.
Powiązania:
https://bibliotekanauki.pl/articles/2014238.pdf
Data publikacji:
2000-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
32.70.Fw
32.70.Cs
Opis:
A high resolution Fourier-transform spectrometer was used to measure branching ratios for 5s-5p, 4d-6s, 6s-6p, 5s-6p, 4d-6p, 4d-7p transitions in neutral germanium and 4d-4f, 4p$\text{}^{2}$-4f, 4p$\text{}^{2}$-5p, 5s-5p, 4p$\text{}^{2}$-4p, 4d-6p, 4p$\text{}^{2}$-6p, 4d-5f, 4p$\text{}^{2}$-5f, 4d-7p, 4p$\text{}^{2}$-7p of singly ionized germanium. Measurements were performed with a hollow cathode as a light source. Spectral lines intensities were measured in a spectral range from 200 to 3500 nm. Absolute transition probabilities for some Ge II lines were obtained using experimental lifetime values for the 4s$\text{}^{2}$4f$\text{}^{2}$F$\text{}_{5}\text{}_{/}\text{}_{2}$ ,$\text{}^{2}$F$\text{}_{7}\text{}_{/}\text{}_{2}$ and 4s$\text{}^{2}$5p$\text{}^{2}$P$\text{}_{1}\text{}_{/}\text{}_{2}$ ,$\text{}^{2}$P$\text{}_{3}\text{}_{/}\text{}_{2}$ levels. Our results for transitions in neutral germanium show that some infrared lines, so far overlooked in spectral analyses, give a strong contribution to Ge spectrum. Our transition probabilities obtained for Ge II lines are lower than all other experimental and theoretical results, in one case even by an order of magnitude.
Źródło:
Acta Physica Polonica A; 2000, 98, 4; 345-351
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Magnetic Equation of State and Transport Properties in Reduced Dimensions
Autorzy:
Warda, K.
Wojtczak, L.
Powiązania:
https://bibliotekanauki.pl/articles/1032847.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.30.Jk
64.60.-i
75.70.Cn
72.10.Fk
Opis:
Basing our considerations on magnetic equation of state applied to the description of magnetic systems of confined geometry we developed the model of calculations of the electrical resistivity for metallic multilayers. It was shown that in the transport of charge in ferromagnetic material d-electrons play an important role. The key parameters in the presented model are: the width of the electron energy band and the shift of the energy level for two spin orientations as well as the Fermi energy and size of the sample (the thickness of magnetic and nonmagnetic layers and the total number of layers). The presented results of calculations for temperature dependence of magnetoresistance are in qualitative agreement with the available experimental data. The model calculations introduced in this paper can be applied to current-in-plane geometry as well as to current-perpendicular-to-plane geometry. The calculations are valid within the limitations of the resistor network model.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 878-880
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis and Elaboration of an Air-Coupled Ultrasound Wideband Sensor Array
Autorzy:
Herman, K.
Stach, L.
Powiązania:
https://bibliotekanauki.pl/articles/1400279.pdf
Data publikacji:
2013-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.60.Fg
43.60.Vx
43.60.-c
43.60.+d
Opis:
In this paper a design process of 64 sensor matrix is described. This study presents adaptation of well known sonar engineering methods of analysis in order to design air operating ultrasound beamforming system. The elaborated system is based on wideband micro electro-mechanical systems. A full digital beamformer with advanced digital signal processing block description is also included. The main goal of the system is direct of arrival of ultrasound wave estimation.
Źródło:
Acta Physica Polonica A; 2013, 123, 1; 31-33
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Some Remarks and Calculations Concerning Collisional Fine Structure Mixing in Alkali Metal Atoms
Autorzy:
Rosiński, K.
Sirko, L.
Powiązania:
https://bibliotekanauki.pl/articles/1887421.pdf
Data publikacji:
1991-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
34.50.-s
Opis:
The analysis of all existing theoretical and experimental results concerning collisional fine structure (FS) mixing, suggesting that their agreement depends on FS separation and FS components intensity anomaly, showed that the test of the theoretical model should be made on sodium atoms. Therefore, the mixing cross sections for the nP (n = 6 ÷ 24) states of sodium atoms colliding with noble gas atoms, N2 and sodium atoms in the ground state have been calculated theoretically. Cross sections also for the lowest nP states of Na and Rb atoms have been estimated.
Źródło:
Acta Physica Polonica A; 1991, 79, 4; 543-548
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Intra-Shallow-Donor Photoconductivity in Semi-Insulating GaAs
Autorzy:
Karpierz, K.
Sadowski, M. L.
Powiązania:
https://bibliotekanauki.pl/articles/1877562.pdf
Data publikacji:
1991-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.40.+w
78.20.ls
78.50.Ec
78.50.Ge
Opis:
The far-infrared photoconductivity of a semi-insulating GaAs sample was measured at 4.2 K as a function of magnetic field up to 7 T. Apart from a peak corresponding to the 1s - 2p$\text{}_{+1}$ transition of the hydrogen-like shallow donor, a well-pronounced structure was observed which does not appear in n-type GaAs.
Źródło:
Acta Physica Polonica A; 1991, 79, 1; 121-124
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hydrogen and its Complexes in Silicon
Autorzy:
Dobaczewski, L.
Bonde Nielsen, K.
Gosciński, K.
Andersen, O.
Powiązania:
https://bibliotekanauki.pl/articles/2014151.pdf
Data publikacji:
2000-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.40.Lq
71.55.Cn
68.55.Ln
Opis:
In this study the technique of Laplace transform (high resolution) deep level transient spectroscopy combined with the uniaxial stress method has been used to study a symmetry and the defect reconfiguration kinetics (the stress induced alignment) of some forms of hydrogen-related centres. We have confirmed the trigonal symmetry of the defect related to the isolated bond centred hydrogen. When hydrogen decorates the vacancy-oxygen pair (the A centre) the apparent defect orthorhombic symmetry is not lowered as a result of a very high hydrogen jumping rate between two unsaturated broken bonds of the vacancy. We also show that the stress-induced defect alignment in some cases can be related to the same microscopic mechanism of the hydrogen motion as it is for the diffusion process.
Źródło:
Acta Physica Polonica A; 2000, 98, 3; 231-239
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electronic and Optical Properties of Heterostructures based on Indium Chalcogenides
Autorzy:
Kharkhalis, L.
Glukhov, K.
Babuka, T.
Powiązania:
https://bibliotekanauki.pl/articles/1033780.pdf
Data publikacji:
2017-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
31.15.A-
31.15.ae
71.15.Mb
71.20.-b
74.20.Pq
73.21.Cd
Opis:
The models of the heterostructures based on the β-InSe, In₄Se₃ and In₄Te₃ crystals were proposed and the first-principles study of their electronic and optical properties were presented. The band spectra, the spatial distributions of the electron density and the absorption coefficients for different polarizations along crystal axes for the heterostructures of the (In₄Se₃)_m/(In₄Te₃)_m and β-InSe/In₄Se₃ type were calculated. The evolution of the changes in both energy spectrum and optical functions of the heterostructures in comparison with the bulk crystals has been analyzed. Our calculations point out the heterostructures stability and good agreement with the experimental investigations of the photosensitivity in the near and middle infrared region.
Źródło:
Acta Physica Polonica A; 2017, 132, 2; 319-321
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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