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Wyszukujesz frazę "J. K" wg kryterium: Wszystkie pola


Tytuł:
Exciton Binding Energy in Extremely Shallow Quantum Wells
Autorzy:
Kossut, J.
Furdyna, J. K.
Powiązania:
https://bibliotekanauki.pl/articles/1877012.pdf
Data publikacji:
1995-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.20.Dx
71.36.+c
73.61.Ga
Opis:
The usual approach to the problem of excitons in semiconductor quantum wells is to assume that both the electron or the hole are primarily localized in the potential well regions defined by the band offsets, i.e., that the quantum wells are deep. We re-examine the problem of the exciton in the presence of a very shallow square well potential due to the (small) conduction and valence band offsets in a semiconducting heterostructure. We show that the combined effects of the shallow well and the Coulomb interaction between the electron and the hole are equivalent to an effective potential acting on the center-of-mass of a three-dimensional exciton. We calculate the shape of such a potential and show it to be satisfactorily approximated by the potential of a parabolic well.
Źródło:
Acta Physica Polonica A; 1995, 87, 2; 528-532
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electronic Spaces and Classification of Multielectron States in Multicentre Systems
Autorzy:
Chatterjee, R.
Lulek, T.
Biel, J. K.
Powiązania:
https://bibliotekanauki.pl/articles/1920612.pdf
Data publikacji:
1992-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
02.40.+m
33.10.Cs
71.10.+x
74.60.-w
Opis:
Electronic structure of a crystal within the tight binding model is described in terms of fibre bundle formalism, with the base and fiber being respectively the set of all sites and the single-centre space of electron spinorbitals. It is based on the Weyl's duality between the symmetric group and the unitary group, and paves the way for a Racah-Wigner type of description of electronic structure in multicentre systems.
Źródło:
Acta Physica Polonica A; 1992, 81, 4-5; 467-474
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Phase Diagram of Zinc-Blende Cd$\text{}_{1-x}$Mn$\text{}_{x}$Se
Autorzy:
Sawicki, M.
Furdyna, J. K.
Luo, H.
Powiązania:
https://bibliotekanauki.pl/articles/1952079.pdf
Data publikacji:
1996-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.-y
75.50.Rr
75.50.Lk
Opis:
The paper reports first magnetic measurements performed on MBE grown epilayers of zinc-blende Cd$\text{}_{1-x}$Mn$\text{}_{x}$Se. For all samples studied in the concentration range 0.24 < x < 0.63 we find at low temperatures a history-dependent magnetic response, suggesting a transition to a spin-glass-like state. The central result of the paper is the presentation of a new, complete magnetic phase diagram for this material.
Źródło:
Acta Physica Polonica A; 1996, 90, 5; 923-926
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
CVD Diamond Films Quality Characterization by ESR, SEM and Raman Spectroscopy
Autorzy:
Fabisiak, K.
Patyk, J. K.
Rozpłoch, F.
Powiązania:
https://bibliotekanauki.pl/articles/1931922.pdf
Data publikacji:
1995-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.50.Jr
Opis:
Polycrystalline diamond films were deposited by electron assisted hot filament chemical vapor deposition method on (001) Si substrate using a mixture of propane-butane and hydrogen as working gas. In morphology investigation of diamond films using scanning electron microscope, it was found that diamond film morphology is changing from (111), for hydrocarbon concentration below 0.5 vol.%, via (100) to the so-called "ball-like" structure. The diamond film quality and defect structures in it were investigated by Raman and electron spin resonance spectroscopy for the purpose of obtaining basic knowledge which will aid the growth of defect free epitaxial diamond film for electronic and optical applications.
Źródło:
Acta Physica Polonica A; 1995, 87, 1; 145-149
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical Properties of Diluted Magnetic Semiconductor Quantum Structures
Autorzy:
Dobrowolska, M.
Luo, H.
Furdyna, J. K.
Powiązania:
https://bibliotekanauki.pl/articles/1931886.pdf
Data publikacji:
1995-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Et
73.20.Dx
68.55.Bd
78.20.Ls
Opis:
Conduction and valence band edges in diluted magnetic semiconductors undergo enormous Zeeman shifts when a magnetic field is applied, reaching values in excess of 100 meV at low temperatures. These Zeeman shifts can thus have profound consequences on the properties of DMS/non-DMS heterostructures, since they provide the opportunity of tuning their band alignment by varying an applied field. This leads to a variety of entirely new effects, and also provides a powerful tool for probing the effect of band alignment on the properties of semiconductor heterostructures in general. We illustrate this with several examples. First, using the ZnSe/ZnMnSe system, we discuss the creation of a spatial spin modulation (spin superlattice). Second, we use the drastic differences in the Zeeman splitting occurring in different layers of a DMS/non-DMS superlattice in order to pinpoint the localization in space of the specific electronic states involved in optical transitions. We illustrate this by investigating the localization of above-barrier states in type-I ZnSe/ZnMnSe superlattices, and of spatially-direct (type-I) excitons which occur in ZnTe/CdMnSe and ZnMnTe/CdSe type-II super-lattices. Finally, we exploit Zeeman tuning to demonstrate the confinement effects which occur in a single quantum barrier.
Źródło:
Acta Physica Polonica A; 1995, 87, 1; 95-106
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Microwave Conductivities of Polymer Films Doped with BEDT-TTF Polyiodides
Autorzy:
Staerk, D.
Helberg, H. W.
Ulański, J.
Jeszka, J. K.
Powiązania:
https://bibliotekanauki.pl/articles/1933365.pdf
Data publikacji:
1995-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.80.Le
72.60.+g
78.70.Gq
Opis:
Conducting reticulate doped polymeric films containing BEDT-TTF iodide crystalline networks have been annealed in order to transform the crystallites into crystal phases with metallic conductivity. The microwave conductivity of these films was measured before and after annealing. The temperature dependence of the conductivity changes dramatically with optimal annealing temperatures and times. This change in the behavior corresponds to the transformation of the α-phase into the superconducting α$\text{}_{t}$-phase observed in (BEDT-TTF)$\text{}_{2}$I$\text{}_{3}$ single crystals.
Źródło:
Acta Physica Polonica A; 1995, 87, 4-5; 797-800
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of Photomemory Effect in Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te$\text{}_{1-y}$Se$\text{}_{y}$:In for Direct Measurements of Magnetization of Bound Magnetic Polarons
Autorzy:
Wojtowicz, T.
Koleśnik, S.
Miotkowski, I.
Furdyna, J. K.
Powiązania:
https://bibliotekanauki.pl/articles/1921550.pdf
Data publikacji:
1992-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.38.+i
75.50.Pp
Opis:
The first direct measurement of the magnetization of donor bound magnetic polarons in diluted magnetic semiconductors is reported. The experiment has been performed taking advantage of photomemory effect found in n-type Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te$\text{}_{1-y}$Se$\text{}_{y}$ crystals doped with In. Good agreement between experimental results and theory of bound magnetic polarons is observed.
Źródło:
Acta Physica Polonica A; 1992, 82, 4; 637-640
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical Absorption of Polymer Films Doped with BEDT-TTF Polyiodides
Autorzy:
Helberg, H. W.
Staerk, D.
Ulański, J.
Jeszka, J. K.
Powiązania:
https://bibliotekanauki.pl/articles/1933405.pdf
Data publikacji:
1995-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.40.Ha
78.30.Jw
74.70.Kn
Opis:
Conducting reticulate doped polymeric films containing BEDT-TTF iodide crystalline network were annealed in order to transform the crystallites into crystal phases with metallic conductivity. Measured optical absorption spectra show that annealing shifts the absorption band to higher frequencies and increases the transparency of the films. This behavior corresponds to the transformation of the α-phase into the superconducting α$\text{}_{t}$-phase observed in (BEDT-TTF)$\text{}_{2}$I$\text{}_{3}$ single crystals.
Źródło:
Acta Physica Polonica A; 1995, 87, 4-5; 893-897
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structure and Properties of Metals
Autorzy:
Kurzydłowski, K. J.
Powiązania:
https://bibliotekanauki.pl/articles/2010997.pdf
Data publikacji:
1999-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
62.20.-x
62.20.Fe
Opis:
Metals are one of the most widely used types of engineering materials. Some of their properties, e.g. elastic constants, can be directly related to the nature of the metallic bonds between the atoms. On the other hand, macro- and microstructural features of metals, such as point defects, dislocations, grain boundaries, and second phase particles, control their yield, flow, and fracture stress. Images of microstructural elements can be obtained by modern imaging techniques. Modern computer aided methods can be further used to obtain a quantitative description of these microstructures. These methods take advantage of the progress made in recent years in the field of image processing, mathematical morphology and quantitative stereology. Quantitative description of the microstructures are used for modeling processes taking place under the action of applied load at a given temperature and test (service) environment. These model considerations can be illustrated on the example of an austenitic stainless steel, which is an important material for power generating and chemical industry. Reports recently published also show that properties of materials can be significantly modified by the effect of free surface. Examples of such situations include environmental effect on the mechanical properties of materials. Data for an austenitic stainless steel is used to discuss contribution of the free surface to the mechanical properties of metals.
Źródło:
Acta Physica Polonica A; 1999, 96, 1; 69-79
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Asymmetric Magnetization Reversal in the Exchange-Biased MnO/(Ga,Mn)As Heterostructure Studied by Ferromagnetic Resonance
Autorzy:
Dziatkowski, K.
Ge, Z.
Liu, X.
Furdyna, J. K.
Twardowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/2046987.pdf
Data publikacji:
2006-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
76.50.+g
75.30.Gw
75.70.Cn
Opis:
We report ferromagnetic resonance study of the magnetization reversal in the exchange-coupled MnO/(Ga,Mn)As system. The low-field parts of ferromagnetic resonance spectra measured along [1/10] and [100] directions of (Ga,Mn)As were combined into hysteresis loops, which under field-cooling conditions similarly to SQUID loops are shifted toward negative magnetic fields. The magnetization reversal process revealed by the loops occurred remarkably asymmetric for both sample configurations.
Źródło:
Acta Physica Polonica A; 2006, 110, 3; 319-324
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nuclear Magnetic Relaxation Dispersion Study of Human Serum Proteins Solutions
Autorzy:
Olszewski, K. J.
Powiązania:
https://bibliotekanauki.pl/articles/1920946.pdf
Data publikacji:
1992-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.90.+d
87.45.-k
Opis:
Nuclear magnetic relaxation dispersion profiles in the Larmor frequency range of 0.02-50 MHz and 277 K has been studied for human serum proteins: albumin, γ-globulins and α, β-globulins in aqueous solutions 3-14 per cent by weight of protein. The linear concentration dependences have been found both for the longitudal relaxation rates for water protons and the dispersive and non-dispersive parts of relaxation profiles. The frequency dependent relaxivities have been calculated, the hydrodynamic effect for the albumin macromolecule Brownian rotational correlation time has been observed and analyzed. The importance of molecular weight of protein for the relaxation processes and its influence for magnetic resonance imaging contrast was discussed.
Źródło:
Acta Physica Polonica A; 1992, 82, 3; 487-494
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Temperature Dependence of Properties of Heterojunctions of Some TCNQ Salts in Polymer Matrices with p- or n-Doped Silicon
Autorzy:
Jeszka, J. K.
Tracz, A.
Boiteux, G.
Seytre, G.
Kryszewski, M.
Powiązania:
https://bibliotekanauki.pl/articles/1933656.pdf
Data publikacji:
1995-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.40.Lq
72.80.Le
Opis:
The temperature dependence of the electrical properties of heterojunctions with silicon formed by conductive organic polymer composites with networks of two complex tetracyanoquinodimethane salts (of N-n-butyl-isoquinolinium and of diethyl methyl sulphonium cations) were studied. We show that it is possible to prepare junctions with quite good rectifying properties, comparable to those obtained using other organic semiconductors. The observed forward-bias current-voltage characteristics can be satisfactorily fitted using the modified Schottky equation. Reverse bias and C-V characteristics show that the transport mechanism, especially in the case of p-Si junctions is more complicated and probably tunnelling between localized levels plays an important role.
Źródło:
Acta Physica Polonica A; 1995, 88, 3; 533-541
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ferromagnetic Resonance Study of Exchange Coupled (Ga,Mn)As/GaAs/(Ga,Mn)As Heterostructures
Autorzy:
Dziatkowski, K.
Ge, Z.
Liu, X.
Furdyna, J. K.
Clerjaud, B.
Twardowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/2047381.pdf
Data publikacji:
2007-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
76.50.+g
75.70.Cn
75.30.Et
85.75.-d
Opis:
Ferromagnetic resonance study of the exchange coupled (Ga,Mn)As/ GaAs/(Ga,Mn)As heterostructures is reported. The measurements were performed on the series of samples with varying thicknesses d$\text{}_{GaAs}$ of nonmagnetic GaAs spacer, established d$\text{}_{GaAs}$-dependent extent of weak and strong interlayer exchange coupling, judging on the observation of one or two ferromagnetic resonance modes.
Źródło:
Acta Physica Polonica A; 2007, 112, 2; 227-232
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Static and Dynamic Spin Organization in Magnetic Semiconductor Nanostructures
Autorzy:
Samarth, N.
Luo, H.
Furdyna, J. K.
Giebultowicz, T. M.
Awschalom, D. D.
Powiązania:
https://bibliotekanauki.pl/articles/1920966.pdf
Data publikacji:
1992-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
75.25.+z
Opis:
We describe experiments which study static and dynamic aspects of Mn spin organization in magnetic semiconductor superlattices and quantum wells. Neutron diffraction studies of ZnSe/MnSe and ZnTe/MnSe superlattices show how static Mn spin organization in these antiferromagnetic layers may be modified by strain and lowered dimensionality. We also use a novel form of femtosecond magnetic spectroscopy to examine magnetic polaron dynamics in diluted magnetic semiconductor quantum wells, and show how the organization of Mn spins by a spin-polarized carrier population may be directly viewed in the time domain.
Źródło:
Acta Physica Polonica A; 1992, 82, 4; 573-584
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Photoluminescence of Donor-Doped ZnSe Films Grown by Molecular Beam Epitaxy
Autorzy:
Karczewski, G.
Hu, B.
Yin, A.
Luo, H.
Dobrowolska, M.
Furdyna, J. K.
Powiązania:
https://bibliotekanauki.pl/articles/1932090.pdf
Data publikacji:
1995-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.55.Ln
78.55.Et
Opis:
We studied the effect of the donor doping of ZnSe films on their photoluminescence properties. The samples were doped during the molecular beam epitaxy growth, either with gallium or with chlorine. As the dopant concentration dose increases, the intensity of the band-edge emission first saturates, and then quenches in favor of the deep-level photoluminescence band. The main effect of donor doping on photoluminescence is a strong increase in intensity of the donor-bound exciton line, referred to as I$\text{}_{2}$. For Ga-doped films deep-band emission is much stronger, and the I$\text{}_{2}$-line is slightly weaker than for Cl-doped films with comparable doping level. The results confirm the superiority of chlorine over gallium as an n-type dopant in ZnSe. We discuss the photoluminescence results and relate them to deep level transient spectroscopy data obtained on the same samples.
Źródło:
Acta Physica Polonica A; 1995, 87, 1; 245-248
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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