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Tytuł:
Metrological Applications of X-ray Waveguide Thin Film Structures in X-ray Reflectometry and Diffraction
Autorzy:
Pełka, J. B.
Lagomarsino, S.
Powiązania:
https://bibliotekanauki.pl/articles/2035489.pdf
Data publikacji:
2002-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.65.-k
61.10.Kw
06.30.Bp
Opis:
The effect of resonance, observed in X-ray waveguide layered structures in a characteristic way influences the scattering properties of the films. It is well known that in the resonant region the reflectivity shows a series of minima, usually very deep and extremely narrow. The positions and depths of the minima depend only on X-ray waveguide structural properties, on the X-ray wavelength and on the incident beam divergence. In the present work we propose and discuss the application of the X-ray waveguide and quasi X-ray waveguide film structures as tools to experimental evaluation of some quantities related to X-ray reflectometric or diffractometric measurements, like the beam divergence, wavelength, or angular distance. Examples of application of the X-ray waveguide as an excellent tool to estimate the effective beam divergence are shown. Properties of the X-ray waveguide elements as a handy wavelength or angular calibration standard are also mentioned.
Źródło:
Acta Physica Polonica A; 2002, 102, 2; 233-238
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Theoretical Description of Shell Filling in Cylindrical Quantum Dots
Autorzy:
Szafran, B.
Bednarek, S.
Adamowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/1992210.pdf
Data publikacji:
1998-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.20.Dx
Opis:
A theoretical quantitative description is given for non-periodic oscillations observed in a current vs. gate voltage characteristics of cylindrical quantum dots. Energy eigenvalues and chemical potentials for a system of N confined electrons (N=1,...,13) are calculated by the unrestricted Hartree-Fock method with a confinement potential proportional to the gate voltage. The positions of the observed peaks of the current are reproduced with a very good accuracy. The non-periodicity of the characteristic is explained as a result of the shell filling, which is a signature of the quantum Coulomb blockade.
Źródło:
Acta Physica Polonica A; 1998, 94, 3; 555-559
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Geometric-Confinement Parameters on the Electronic Properties of Quantum Ring
Autorzy:
Moskal, S.
Spisak, B. J.
Powiązania:
https://bibliotekanauki.pl/articles/2047364.pdf
Data publikacji:
2007-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.23.Ra
73.22.Dj
73.43.Cd
Opis:
We investigate the electronic properties of the quantum rings modelled by a two-dimensional non-singular potential with the cylindrical symmetry as well as the influence of the potential's parameters on energy spectra. In the presence of the external magnetic field we also calculated the persistent currents in such structures in the ballistic regime.
Źródło:
Acta Physica Polonica A; 2007, 112, 1; 101-112
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Phase Structure in Fe-Cr-Co Permanent Magnet Alloy
Autorzy:
Olszewski, J.
Szymura, S.
Wójcik, J.
Wysłocki, B.
Powiązania:
https://bibliotekanauki.pl/articles/1861167.pdf
Data publikacji:
1994-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.60.Gm
75.60.Ej
Opis:
The Mössbauer spectroscopy, electron microscopy and magnetization measurements were used in order to describe structural changes in Fe$\text{}_{58.75}$Cr$\text{}_{29.4}$Co$\text{}_{11.85}$ alloy during magnetic hardening. Multiphase structure was found in alloy with best magnetic properties.
Źródło:
Acta Physica Polonica A; 1994, 85, 1; 205-208
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Transport and Capacitance Spectroscopy of Quantum Dots
Autorzy:
Adamowski, J.
Bednarek, S.
Szafran, B.
Powiązania:
https://bibliotekanauki.pl/articles/2027454.pdf
Data publikacji:
2001-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.22.-f
73.63.-b
Opis:
A review of recent theoretical studies on a single-electron tunneling in quantum dots is presented. This effect underlies the transport spectroscopy performed on the vertical gated quantum dots and the capacitance spectroscopy on the self-assembled quantum dots. The conditions of the single-electron tunneling are formulated in terms of electrochemical potentials of the electrons in the leads and in the quantum dot. The electrochemical potentials for the electrons confined in the quantum dots can be calculated by solving the many-electron Schrödinger equation. The results obtained by the Hartree-Fock method are presented. For the vertical gated quantum dot, the realistic confinement potential is obtained from the Poisson equation. The application of the self-consistent procedure to the solution of the Poisson-Schrödinger problem is discussed. The calculated positions of the current peaks at zero bias and boundaries of the Coulomb diamonds for non-zero bias are in good agreement with experiment. The influence of an external magnetic field on the single-electron tunneling is also discussed. The spin-orbital configurations of the electrons confined in the quantum dots change with the magnetic field, which leads to features observed in the current-voltage and capacitance-voltage characteristics.
Źródło:
Acta Physica Polonica A; 2001, 100, 2; 145-163
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nonsequential Double Ionization of Atoms in Strong Laser Pulses
Autorzy:
Prauzner-Bechcicki, J. S.
Sacha, K.
Eckhardt, B.
Zakrzewski, J.
Powiązania:
https://bibliotekanauki.pl/articles/2047833.pdf
Data publikacji:
2007-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
32.80.Rm
32.80.Fb
03.65.-w
02.60.Cb
02.60.-x
Opis:
It is now possible to produce laser pulses with reproducible pulse shape and controlled carrier envelope phase. It is discussed how that can be explored in double ionisation studies. To this end we solve numerically the Schrödinger equation for a limited dimensionality model which nevertheless treats electron repulsion qualitatively correctly and allows to study correlation effects due to the Coulomb repulsion.
Źródło:
Acta Physica Polonica A; 2007, 112, 4; 699-706
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Changes in Optical Properties of Molecular Nanostructures
Autorzy:
Vučenović, S.
Šetrajčić, J.
Markoski, B.
Mirjanić, D.
Pelemiš, S.
Škipina, B.
Powiązania:
https://bibliotekanauki.pl/articles/1537873.pdf
Data publikacji:
2010-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
77.55.+f
78.20.-e
78.66.-w
78.67.-n
Opis:
This paper represents an overview about exciton systems in the molecular nanostructures (ultra thin films and superlattices) and their implications on optical properties, primarily on absorption coefficient, which is given in the form of dielectric permittivity. With utilization of Green's function method, we have calculated dispersion law, spectral weight of exciton states and dielectric permittivity for every type of nanostructures. All obtained results are compared with optical properties in bulk crystals. Dielectric permittivity in all types of nanostructures shows very narrow and discrete dependence of external electromagnetic field frequency, which is a consequence of the expressed quantum effects, very thin thickness in these structures (or at least one dimension confinement) and boundary conditions.
Źródło:
Acta Physica Polonica A; 2010, 117, 5; 764-767
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reappearance of Antiferromagnetic Order in $Nd_{0.9}Ca_{0.1}BaCo_{2}O_{5+δ}$ for δ > 0.51
Autorzy:
Piętosa, J.
Kolesnik, S.
Puźniak, R.
Dabrowski, B.
Powiązania:
https://bibliotekanauki.pl/articles/1374353.pdf
Data publikacji:
2014-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Kz
75.50.Gg
62.50.-p
Opis:
The absence of the antiferromagnetic order in $Nd_{0.9}Ca_{0.1}BaCo_2O_{5.5}$ has been found to remain unchanged by applying a hydrostatic pressure of 10 kbar. In magnetic studies of polycrystalline $Nd_{0.9}Ca_{0.1}BaCo_2O_{5+δ}$ (δ=0.07-0.69), we have found a reappearance of the antiferromagnetic phase, caused by an increase in oxygen index δ above 0.51 related to extra oxygen ions addition into the $NdO_{δ}$ plane. For the samples with δ=0.555 and 0.59, a coexistence of well developed antiferromagnetic phase with ferrimagnetic one is evidenced.
Źródło:
Acta Physica Polonica A; 2014, 126, 4a; A-50-A-52
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electron Pairs and Excitons in Quasi-One-Dimensional Nanostructures
Autorzy:
Bednarek, S.
Szafran, B.
Chwiej, T.
Adamowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/2036023.pdf
Data publikacji:
2003-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.21.-b
Opis:
A theoretical study of two-particle systems in quasi-one-dimensional quantum wires and quantum dots is presented. We have derived the analytical formula for the effective interaction potential between the charge carriers confined laterally by a strong parabolic potential and applied this formula to electron pairs in single and double quantum dots and to excitons in quantum wires. In the single quantum dot of the sufficiently large size, we have found the Wigner-type localization.
Źródło:
Acta Physica Polonica A; 2003, 103, 6; 567-572
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Oscillations in Reflectivity of Samples with X-ray Waveguide Layers
Autorzy:
Pełka, J. B.
Lagomarsino, S.
Di Fonzo, S.
Jark, W.
Domagała, J.
Powiązania:
https://bibliotekanauki.pl/articles/1945221.pdf
Data publikacji:
1996-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.65.+g
78.20.Ci
Opis:
The glancing-angle reflectivity profiles in samples containing an X-ray waveguide layer are studied. Oscillations observed at angles within the region of resonance and above, are interpreted by angle dependent interference of the monochromatic X-ray beam in thin layer. The discussion is extended to the structures composed of more than one layer. Experimental reflectivity spectra recorded with Cu K$\text{}_{α}$ radiation are compared with the theoretical calculations. It leads to the model of oscillations in reflectivity consistent both for the resonant and non-resonant regions, and clarifies interpretation of oscillations in the region above the resonances. A brief discussion of potential applications of the reflectivity spectra to the studies of structure of thin layers is done.
Źródło:
Acta Physica Polonica A; 1996, 89, 3; 323-328
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Surface Modification of Metallic Targets with Ultrashort Laser Pulses
Autorzy:
Gakovic, B.
Stasic, J.
Petrovic, S.
Radak, B.
Krmpot, A.
Jelenkovic, B.
Trtica, M.
Powiązania:
https://bibliotekanauki.pl/articles/1795615.pdf
Data publikacji:
2009-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.62.-b
61.80.Ba
61.82.Bg
79.20.Eb
Opis:
Interaction of pulsed femtosecond Ti:sapphire laser (160 fs), operating at high repetition rate (75 MHz) at 800 nm, with nickel-based superalloy Inconel 600 and tungsten-titanium (WTi) target was studied. The WTi target was in form of thin film deposited on silicon substrate. Low laser fluence of maximum 50 mJ/cm^{2} had modified the target surface during irradiation/exposure time of seconds or minutes. The radiation absorbed from the laser beam generates at the surface a series of effects, such as direct material vaporization, formation of clusters, etc. Morphological features of the targets can be summarized as: (a) intensive removal of material and crater appearance; (b) creation of nanostructures; (c) microcracking, etc. Ablation of Inconel 600 surface is effective, resulting in formation of holes with small diameter ( ≤ 10 μm) and relatively large depth ( ≤ 50 μm). In case of WTi target/thin film, the surrounding rim is not so expressed, and crater depths are lower. It can be concluded that the average laser power of the order of watts, pulse energies of the order of nanojoules and high repetition rates (MHz range) can successfully modify metallic materials.
Źródło:
Acta Physica Polonica A; 2009, 116, 4; 611-613
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High-Pressure Microwave Study of YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$-Pb(Sc$\text{}_{0.5}$Ta$\text{}_{0.5}$)O$\text{}_{3}$ Composite
Autorzy:
Czyżak, B.
Stankowski, J.
Hilczer, B.
Krupski, M.
Morawski, P.
Andrzejewski, B.
Marfaing, J.
Régnier, S.
Caranoni, C.
Powiązania:
https://bibliotekanauki.pl/articles/1964222.pdf
Data publikacji:
1997-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
77.80.-e
Opis:
The ferroelectric relaxor Pb(Sc$\text{}_{0.5}$Ta$\text{}_{0.5}$)O$\text{}_{3}$-superconductor YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$ 50% in weight composite exhibits the onset critical temperature T$\text{}_{c}$=95 K. High pressure studies yield the factor dT$\text{}_{c}$/dp of 1.0 K/GPa, close to the value observed for a pure YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$ compound. The microwave absorption studies show the significant role of the intergrain weak links.
Źródło:
Acta Physica Polonica A; 1997, 91, 6; 1103-1109
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Charge-Ordering and Magnetoelastic Coupling Effects on the Magnetocaloric Properties of Manganites
Autorzy:
Reis, M. S.
Gomes, A. M.
Araújo, J. P.
Tavares, P. B.
Amaral, J. S.
Oliveira, I. S.
Amaral, V. S.
Powiązania:
https://bibliotekanauki.pl/articles/2037124.pdf
Data publikacji:
2004
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.30.Kz
75.80.+q
Opis:
A study of the magnetocaloric properties of La$\text{}_{1-x-y}$Y$\text{}_{y}$Ca$\text{}_{x}$MnO$\text{}_{3}$, La$\text{}_{1-x}$Cd$\text{}_{x}$MnO$\text{}_{3}$, and Pr$\text{}_{1-x}$Ca$\text{}_{x}$MnO$\text{}_{3}$ manganites with ferromagnetic and charge-ordered states is presented. The ferromagnetic lanthanum manganites show a negative entropy change peakΔ S under the application of a magnetic field at the Curie temperature. However, the magnetoelastic coupling effects lead to a first-order paramagnetic-ferromagn etic transition and an increasedΔ S compared to simple ferromagnets. This effect is analyzed in the framework of the Landau theory of phase transitions which shows a comparable influence of the magnetoelastic couplings and the ordinary magnetic ordering effect. The Pr$\text{}_{1-x}$Ca$\text{}_{x}$MnO $\text{}_{3}$ system shows a rich electric and magnetic phase diagram, with a ferromagnetic insulator phase for 0.15
Źródło:
Acta Physica Polonica A; 2004, 105, 1-2; 163-171
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Design Rules for Manganites with Novel Magnetic and Electronic Properties
Autorzy:
Dabrowski, B.
Chmaissem, O.
Mais, J.
Kolesnik, S.
Powiązania:
https://bibliotekanauki.pl/articles/2037095.pdf
Data publikacji:
2004
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.12.-q
75.50.-y
Opis:
We have been systematically developing strategies for making new perovskite manganites with novel magnetic and electronic properties. This effort requires a two-fold approach: understanding the dependence of properties on chemical and structural factors and development of the ability to synthesize desired compounds. We show that, similar to other single valent 3d systems, the magnetic superexchange interactions in AMnO$\text{}_{3}$ manganites (A = rare or alkaline earth's) are dependent on the Mn-O-Mn bond angle which is a function of interatomic distances A-O and Mn-O. The local structural disorder on the A-site suppresses magnetic interactions. Recently, by comparing disordered (randomly mixed La/Ba) and ordered (forming Ba/La/Ba layers along the c-axes) perovskites we have demonstrated much more conspicuous effects of structural and charge disorder for mixed-valent manganites. We show that by stabilizing the ordered structure; i.e., by suppressing local structural and charge disorder on the A-site, a substantial increase in T$\text{}_{C}$ from 340 to 365~K can be achieved. A similar control of order on the Mn-site was achieved for SrMn$\text{}_{1-y}$Ga$\text{}_{y}$ O$\text{}_{3-\text{}_{y}\text{}_{/}\text{}_{2}$ compounds near y=0.5, while SrMn$\text{}_{1-y}$Fe$\text{}_{y}$O$\text{}_{3}$ compounds are always randomly mixed. To achieve these compounds, we have been systematically developing special synthesis techniques for extending chemical composition ranges far beyond those previously achieved, developing rules for predicting which compositions should be possible to produce by these special techniques, and establishing methods for selectively ordering or disordering mixtures of metal atoms on the A- or Mn-sites.
Źródło:
Acta Physica Polonica A; 2004, 105, 1-2; 45-56
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dielectric Properties of Liquid Crystalline Isothiocyanato-tolane Derivatives with Fluorine Atom at Various Lateral Positions
Autorzy:
Czub, J.
Urban, S.
Dąbrowski, R.
Gestblom, B.
Powiązania:
https://bibliotekanauki.pl/articles/2043376.pdf
Data publikacji:
2005-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.Md
77.22.Gm
77.84.Nh
Opis:
Dielectric studies were performed for several isothiocyanato-tolane compounds having the F atom attached to the benzene rings at different lateral positions and the alkoxy or alkyl chain at the p-position. They form the nematic phase in broad temperature intervals. The static as well as dynamic properties of the compounds in the nematic and isotropic phases were studied. Tensor permittivity components: ε$\text{}_{ǁ}$, ε$\text{}_{⊥}$, Δε, as functions of temperature were measured. The complex dielectric permittivity, ε$\text{}^{*}$(f)=ε'(f)-iε''(f), was measured in the frequency range of 1 kHz - 3 GHz from which the relaxation times τ$\text{}_{ǁ}$ and τ$\text{}_{⊥}$ were calculated. The order parameter S(T) was determined from the dielectric data. It was found that the close vicinity of the F atom and the alkoxy group results in blocking of the internal rotation of the wing around the O-phenyl bond.
Źródło:
Acta Physica Polonica A; 2005, 107, 6; 947-958
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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