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Wyszukujesz frazę "Wilamowski, J." wg kryterium: Autor


Tytuł:
Coulomb versus Madelung Gap: Ordering in a System of Point Charges
Autorzy:
Sobkowicz, P.
Wilamowski, Z.
Kossut, J.
Powiązania:
https://bibliotekanauki.pl/articles/1929618.pdf
Data publikacji:
1993-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.-i
72.20.Fr
Opis:
Spatial correlations of impurity charges in a mixed valence regime are studied with the use of Monte Carlo simulations. The influence of various kinds of disorder on the one-particle density of states is determined. A continuous transitions from a "soft" Coulomb gap (density of states vanishing only at the chemical potential) to a "hard" gap (with a finite range of energies with vanishing density of states) is found, driven by decreasing amount of built-in disorder in the system. The "hard" Coulomb gap resembles the Madelung gap, found in crystalline arrangements of charges. The similarity reflects the fact that both the Coulomb and Madelung gaps are manifestations of the same phenomenon, resulting from ordering of the positions of point charges, the only difference being the range of correlations.
Źródło:
Acta Physica Polonica A; 1993, 84, 3; 515-518
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Potential Fluctuations in HgSe:Fe,Ga - a Numerical Study
Autorzy:
Sobkowicz, P.
Wilamowski, Z.
Kossut, J.
Powiązania:
https://bibliotekanauki.pl/articles/1861521.pdf
Data publikacji:
1993-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.-i
Opis:
We study spatial correlation of donor charges in HgSe:Fe,Ga using a few simple quantities (mean electrostatic energy of various donor sites, fluctuations of the electrostatic potential). The study uses Monte Carlo simulation techniques. We are able to indicate general trends in the behavior of the correlation when proportion of correlating (Fe^{3+}) and noncorrelating (Ga) charged centers in the sample is changed.
Źródło:
Acta Physica Polonica A; 1993, 84, 4; 645-648
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Monte Carlo Simulations of Spatial Correlations of Charged Centers in δ-Doped Layers
Autorzy:
Sobkowicz, P.
Wilamowski, Z.
Kossut, J.
Powiązania:
https://bibliotekanauki.pl/articles/1921559.pdf
Data publikacji:
1992-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Eq
73.20.Dx
71.45.Gm
Opis:
Results of Monte Carlo simulations of a 2D system of charged donors are presented. They enable to study the effects related to a spatial correlation of donor charges located on a random donor matrix. A qualitative difference between DX$\text{}^{+}$ and DX¯ models is observed. In the first case, strong temperature dependence of the correlations and a "freezing-like" behaviour is found. The origin of the freezing is traced to the random distribution of donor sites by comparing the system with a liquid-like model where the charges may assume arbitrary positions within a plane. In the second case only nearest-neighbour correlations are observed. The simulations have direct application in analysis of the behaviour of the DX centers in the GaAs planarly doped with Si.
Źródło:
Acta Physica Polonica A; 1992, 82, 4; 645-648
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Localized Spin Relaxation Due To Coupling To Effective Mass States
Autorzy:
Wilamowski, Z.
Dmochowski, J. E.
Jantsch, W.
Powiązania:
https://bibliotekanauki.pl/articles/1968446.pdf
Data publikacji:
1997-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Jm
75.50.-y
Opis:
The EPR of residual Mn in CdF$\text{}_{2}$ doped with Y, In and Ga is investigated. Although these donors are barely seen in EPR, they manifest themselves by a new effect: a drastic resonant reduction in the longitudinal relaxation rate of Mn which occurs only if the Zeeman splitting of the two subsystems coincide. In this situation, the saturation of those of the six Mn hyperfine lines is weakened which coincide with the shallow donor resonance.
Źródło:
Acta Physica Polonica A; 1997, 92, 5; 1055-1058
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Consequences of Spatial Fluctuation of Coulomb Potential in AlGaAs with DX Centers
Autorzy:
Wilamowski, Z.
Kossut, J.
Jantsch, W.
Ostermayer, G.
Powiązania:
https://bibliotekanauki.pl/articles/1890983.pdf
Data publikacji:
1991-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Dp
71.45.Jp
72.80.Ey
Opis:
Electric charges on randomly distributed impurities in semiconductors produce a spatially fluctuating potential. When the impurities are partially filled, their occupancy is not random but there appears a spatial correlation of the impurity charges appearing due to the inter-impurity Coulomb interactions. We show that when these interactions are taken into account then (i) the activation energy of the electron concentration, (ii) thermal emission kinetics, (iii) capture kinetics, (iv) persistent photoconductivity kinetics and (v) the electron mobility (in a steady state as well as during transients) in GaAlAs:Si can be explained in a consistent way. The energy diagram con cerning the DX center levels with respect to minima of the conduction band as well as the capture and emission barriers (including the effect of the alloy splitting) is constructed within an approach making use of the notion of the impurity self-screening.
Źródło:
Acta Physica Polonica A; 1991, 80, 3; 385-388
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spatial Correlation of Impurity Charges Induced by Coulomb Interactions - Application to DX Centers in GaAs
Autorzy:
Kossut, J.
Wilamowski, Z.
Dietl, T.
Świątek, K.
Powiązania:
https://bibliotekanauki.pl/articles/1877485.pdf
Data publikacji:
1991-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.80.Ey
72.20.Dp
71.55.Eq
Opis:
The electron mobility enhancement observed in heavily doped GaAs under hydrostatic pressure is interpreted in terms of spatial correlation between the donor charges within partially occupied system of impurities induced by strong inter-donor Coulomb interaction. A simple analytic theory is given for both DX$\text{}^{0}$ and DX$\text{}^{-}$ models of the impurity state. The mobility is shown to increase together with pressure in both models. Estimates of the energy of the DX level are strongly perturbed by the inter-donor Coulomb interactions.
Źródło:
Acta Physica Polonica A; 1991, 79, 1; 49-58
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electrically Detected Magnetic Resonance
Autorzy:
Fedorych, O. M.
Wilamowski, Z.
Jantsch, W.
Sadowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/2038127.pdf
Data publikacji:
2004-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Pk
72.25.Rb
73.21.Fg
Opis:
We compare the results of electrically detected magnetic resonance in a 2D electron gas in Si/SiGe quantum wells with transport and magnetic resonance measurements on ferromagnetic Ga$\text{}_{1-x}$Mn$\text{}_{x}$As. The results lead us to the conclusion that observation of electrically detected magnetic resonance is possible only in the case of a slow spin relaxation, where the microwave resonant absorption leads to a noticeable change of spin magnetization.
Źródło:
Acta Physica Polonica A; 2004, 105, 6; 591-598
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electron Scattering and the Band Structure of Mixed Crystals Hg$\text{}_{1-x}$Fe$\text{}_{x}$Se
Autorzy:
Skierbiszewski, C.
Wilamowski, Z.
Suski, T.
Kossut, J.
Witkowska, B.
Powiązania:
https://bibliotekanauki.pl/articles/1923803.pdf
Data publikacji:
1992-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.10.Fk
72.20.Fr
72.80.Jc
Opis:
In this paper the dependence of the band structure and the electron scattering mechanisms on the molar fraction x are studied in Hg$\text{}_{1-x}$Fe$\text{}_{x}$Se. The crossover from the zero-gap band to the open band-gap configuration at x ≈ 0.08 is predicted. We explain the drop of the electron mobility for x > 0.002 by the alloy scattering mechanism.
Źródło:
Acta Physica Polonica A; 1992, 82, 5; 809-812
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ferromagnetic, Ferrimagnetic and Spin-wave Resonances in GaMnAs Layers
Autorzy:
Fedorych, O.
Byszewski, M.
Wilamowski, Z.
Potemski, M.
Sadowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/2035590.pdf
Data publikacji:
2002
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Eq
76.30.Fc
75.50.Pp
75.30.Gw
Opis:
Molecular beam epitaxy grown Ga$\text{}_{1-x}$Mn$\text{}_{x}$As layers were investigated by means of magnetic resonances. With an increase in Mn concentration, x, the spectrum changes from the (i) paramagnetic one, with resolved fine and hyperfine structures, typical of S=5/2 spin of substitutional Mn$\text{}^{2+}$ ions, for very diluted alloy, via (ii) paramagnetic spectrum, where the fine and hyperfine structures are averaged by a long range Mn$\text{}^{2+}$-Mn$\text{}^{2+}$ exchange coupling, (iii) single, isotropic line of ferromagnetic resonance. Insulator to metal transition is accompanied with occurrence of (iv) a very complex spectrum of the ferrimagnetic resonance, accompanied with the well-resolved spin wave resonance. Reentrance to insulator phase for the most condensed alloys is accompanied with the reentrance to (v) ferromagnetic phase. The data confirm that the effective mass holes transfer the exchange interaction between localized Mn$\text{}^{2+}$ spins.
Źródło:
Acta Physica Polonica A; 2002, 102, 4-5; 617-625
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electric Dipole and Current Induced Spin Resonances of Shallow Donor in ZnO
Autorzy:
Michaluk, E.
Błoniarz, J.
Pabich, M.
Wilamowski, Z.
Mycielski, A.
Powiązania:
https://bibliotekanauki.pl/articles/2046940.pdf
Data publikacji:
2006-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Gs
76.30.-v
71.70.Ej
Opis:
In this paper we present our observation of electric dipole spin resonance and current induced spin resonance in ZnO bulk crystals, both effects result from spin-orbit coupling. Electric dipole spin resonance originates from admixture of spin state due to spin-orbit interaction which leads to probability of spin-flip caused by electric component of microwave field. In current induced spin resonance phenomenon the electric component of microwave field induces electron motion leading to mean ac spin-orbit field that acts on electron spin. Spin-orbit interaction can be described in terms of the Rashba field, an effective magnetic field that induce spin resonance. In contrast to magnetic and electric dipole spin resonances the current induced resonance is characterized by dispersive-like line shape.
Źródło:
Acta Physica Polonica A; 2006, 110, 2; 263-270
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Resonance Studies of the Origin of Ferromagnetism in Ga$\text{}_{1-x}$Mn$\text{}_{x}$As
Autorzy:
Fedorych, O. M.
Wilamowski, Z.
Potemski, M.
Byszewski, M.
Sadowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/2036029.pdf
Data publikacji:
2003-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Eq
76.30.Fc
75.50.Pp
75.30.Gw
Opis:
Different types of magnetic resonance observed in Ga$\text{}_{1-x}$Mn$\text{}_{x}$As reflect three different magnetic phases: para-, ferro-, and ferrimagnetic. Ferromagnet is characterized by single isotropic resonance line. A complex spectrum in ferrimagnet can be described by g factor equal to 1.44 and a sum of an axial and cubic anisotropy field. The axial field is by an order of magnitude greater than the cubic one. The complex structure of ferrimagnetic resonance is attributed to spin-wave resonance. Quantitative analysis of the dispersion of spin wave shows that the range of exchange coupling is very long, of the order of 25 nm, while spin-wave stiffness and the total exchange field are very small. The exchange field as evaluated from spin wave is by two orders of magnitude smaller than the Zener field corresponding to the critical temperature.
Źródło:
Acta Physica Polonica A; 2003, 103, 6; 607-612
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pressure Study of Charged Donor Ordering in HgSe Doped with Iron and Gallium
Autorzy:
Skierbiszewski, C.
Suski, T.
Kossut, J.
Wilamowski, Z.
Dobrowolski, W.
Witkowska, B.
Powiązania:
https://bibliotekanauki.pl/articles/1891020.pdf
Data publikacji:
1991-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.10.Fk
72.20.Fr
72.80.Jc
Opis:
Transport experiments (Hall effect and conductivity) under hydrostatic pressure up to 1 GPa at liquid helium temperatures on HgSe: Fe, Ga (N$\text{}_{Fe}$ = 2 x 10$\text{}^{19}$ cm$\text{}^{-3}$; 0 ≤ N$\text{}_{Ga}$ ≤ 10$\text{}^{19}$ cm$\text{}^{-3}$) were performed. The results show that the gallium co-doping of HgSe:Fe decreases the degree of spatial correlations between charged impurities. Under the hydrostatic pressure, used as a tool for changing the ratio of the charged to neutral impurities, this effect is even more pronounced. A qualitative agreement between the calculation within the short-range correlation model and our experimental data is achieved.
Źródło:
Acta Physica Polonica A; 1991, 80, 3; 401-404
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
PbSe:Cr - New Resonant Donor System
Autorzy:
Story, T.
Wilamowski, Ż.
Grodzicka, E.
Dobrowolski, W.
Witkowska, B.
Voiron, J.
Powiązania:
https://bibliotekanauki.pl/articles/1932086.pdf
Data publikacji:
1995-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pρ
72.20.My
Opis:
Hall effect, conductivity, electron paramagnetic resonance and magnetization of Pb$\text{}_{1-x}$Cr$\text{}_{x}$Se (x ≤ 0.01) crystals were measured as a function of Cr content and electron concentration. The experimental results suggest that Cr in PbSe creates a resonant donor state with the energy of about 125 meV above the bottom of the conduction band.
Źródło:
Acta Physica Polonica A; 1995, 87, 1; 229-232
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
PVT-Grown Single Crystals of Cd$\text{}_{1-x}$Zn$\text{}_{x}$Te (x ≤ 0.25) and ZnTe as Substrates for Epitaxy
Autorzy:
Mycielski, A.
Szadkowski, A.
Łusakowska, E.
Kowalczyk, L.
Domagała, J.
Bąk-Misiuk, J.
Wilamowski, Z.
Witkowska, B.
Powiązania:
https://bibliotekanauki.pl/articles/1991957.pdf
Data publikacji:
1998-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Dz
81.10.Bk
Opis:
The process of growth of single crystals of Cd$\text{}_{1-x}$Zn$\text{}_{x}$Te (x ≤ 0.25) and ZnTe by physical vapour transport has been optimized and the twin-free single crystals with a very good crystal structure and low density of dislocations are grown as substrates for MBE and other techniques of epitaxy. Characterization of the crystals is described.
Źródło:
Acta Physica Polonica A; 1998, 94, 3; 441-445
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Exciton Transfer in Multiple Quantum Well Structures of CdTe/CdMnTe Grown by Molecular Beam Epitaxy
Autorzy:
Godlewski, M.
Surma, M.
Wilamowski, Z.
Wojtowicz, T.
Karczewski, G.
Kossut, J.
Holtz, P. O.
Bergman, J. P.
Monemar, B.
Powiązania:
https://bibliotekanauki.pl/articles/1968091.pdf
Data publikacji:
1997-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.47.+p
78.55.Et
Opis:
The direct evidence for the efficient transfer of excitons from 4 nm and 6 nm to 10 nm wide CdTe quantum wells is presented based on the results of photoluminescence and photoluminescence excitation investigation. Efficient transfer is observed for quantum wells separated by thick (50 nm) CdMnTe barriers containing 10% or 30% Mn fraction. A new mechanism of the transfer is proposed, which involves long range dynamic magnetic interactions between free/bound excitons and Mn ions in the CdMnTe barrier regions of the structure.
Źródło:
Acta Physica Polonica A; 1997, 92, 4; 761-764
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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