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Wyszukujesz frazę "Sadowski, R." wg kryterium: Autor


Wyświetlanie 1-14 z 14
Tytuł:
Optical Pump - Terahertz Probe Measurement of the Electron Dynamics in Ga$\text{}_{1-x}$Mn$\text{}_{x}$As
Autorzy:
Šustavičiūtė, R.
Balakauskas, S.
Adomavičius, R.
Krotkus, A.
Sadowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/2047687.pdf
Data publikacji:
2007-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.65.Re
07.57.Hm
78.47.+p
75.50.Pp
Opis:
An optical pump - terahertz probe technique was used for measuring electron lifetime in various Ga$\text{}_{1-x}$Mn$\text{}_{x}$As epitaxial layers with the subpicosecond temporal resolution. The measurements were performed on the samples with x up to 2%, which had large resistivities and were transparent in a THz frequency range. It has been found that an induced THz absorption relaxation is the fastest and electron lifetimes are the shortest for the samples with the smallest Mn content. For the samples with x=0.3% and x=2% this relaxation becomes much slower; its rate is comparable to the carrier recombination rate in Ga$\text{}_{1-x}$Mn$\text{}_{x}$As substrate.
Źródło:
Acta Physica Polonica A; 2007, 112, 2; 311-314
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
STM/AFM Images and Tunneling Spectra of Nd$\text{}_{2-x}$Ce$\text{}_{x}$CuO$\text{}_{4-y}$ Single Crystals
Autorzy:
Susła, B.
Sadowski, W.
Klimczuk, T.
Czajka, R.
Powiązania:
https://bibliotekanauki.pl/articles/1964375.pdf
Data publikacji:
1997-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.16.Ch
74.72.Jt
68.35.Bs
Opis:
The results of the scanning tunneling microscopy and spectroscopy as well as atomic force microscopy measurements on the Nd$\text{}_{2-x}$Ce$\text{}_{x}$CuO$\text{}_{4-y}$ single crystals in ambient conditions are reported. Using the scanning tunneling microscopy we were able to modify the Nd$\text{}_{2-x}$Ce$\text{}_{x}$CuO$\text{}_{4-y}$ ab-plane in air under the conditions of sample bias voltage V$\text{}_{t}$=500 mV and set current I$\text{}_{s}$=0.3 nA. It is possible to prepare atomically flat and clean surfaces as well as to create new structures in a nanometer scale in these electron-doped materials. The similar processes were not observed during atomic force microscopy imaging.
Źródło:
Acta Physica Polonica A; 1997, 92, 1; 209-214
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Different Signals of Magnetic Resonance Imaging and Ultrasound from Substantia Nigra in Parkinsons Disease and Control - Is Iron the Cause?
Autorzy:
Szlachta, K.
Sadowski, K.
Kuliński, R.
Gałązka-Friedman, J.
Friedman, A.
Powiązania:
https://bibliotekanauki.pl/articles/1490100.pdf
Data publikacji:
2012-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
87.19.L-
Opis:
Motor symptoms of Parkinson's disease are caused by a progressive degeneration of substantia nigra, a small structure located deep in the brain. The cause of this process is unknown but may be related to iron mediated oxidative stress. The aim of this study was to understand the mechanism of the change of magnetic resonance and ultrasound signals found in patients with Parkinson's disease, which were attributed by several authors to an important increase of the concentration of iron in substantia nigra. USG and MRI measurements were performed on phantoms simulating human brain to which high amounts of iron were introduced. The USG signal was unaffected by insertion of iron-loaded ferritin, while it was by insertion of glial tissue. Injections of iron-loaded ferritin and iron ions to the phantoms decreased $T_2$ relaxation time. Our results suggest that the observed change of the signal from Parkinsonian brains is probably due to a proliferation of glia and not to an increase of the concentration of iron.
Źródło:
Acta Physica Polonica A; 2012, 121, 2; 454-456
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Interval Identification of FMR Parameters for Spin Reorientation Transition in (Ga,Mn)As
Autorzy:
Gutowski, M.
Stefanowicz, W.
Proselkov, O.
Sawicki, M.
Żuberek, R.
Sadowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/1428597.pdf
Data publikacji:
2012-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
07.05.Kf
68.47.Fg
75.30.Gw
75.50.Pp
75.70.-i
75.70.Ak
75.70.Cn
75.70.Rf
76.50.+g
Opis:
In this work we report results of ferromagnetic resonance studies of a 6% 15nm (Ga,Mn)As layer, deposited on (001)-oriented GaAs. The measurements were performed with in-plane oriented magnetic field, in the temperature range between 5 K and 120 K. We observe a temperature induced reorientation of the effective in-plane easy axis from $[\overline{1}10]$ to [110] direction close to the Curie temperature. The behavior of magnetization is described by anisotropy fields, $H_{eff}$ (=4π $M-H_{2⊥}$), $H_{2∥},$ and $H_{4∥}$. In order to precisely investigate this reorientation, numerical values of anisotropy fields have been determined using powerful - but still largely unknown - interval calculations. In simulation mode this approach makes possible to find all the resonance fields for arbitrarily oriented sample, which is generally intractable analytically. In "fitting" mode we effectively utilize full experimental information, not only those measurements performed in special, distinguished directions, to reliably estimate the values of important physical parameters as well as their uncertainties and correlations.
Źródło:
Acta Physica Polonica A; 2012, 121, 5-6; 1228-1230
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Superconducting Transition in Granular Bi-Sr-Ca-Cu-O Superconductors
Autorzy:
Gazda, M.
Kusz, B.
Sadowski, W.
Stizza, S.
Natali, R.
Di Stasio, V.
Powiązania:
https://bibliotekanauki.pl/articles/2046731.pdf
Data publikacji:
2006-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.62.-c
74.81.Bd
74.72.Hs
Opis:
In this work we study the superconducting transition in the samples containing relatively small granules of high-T$\text{}_{c}$ Bi-Sr-Ca-Cu-O superconductors. The samples were obtained by the glass-ceramic technology. Two-stage character of the superconducting transition was studied. Pairing transition temperature depends on the magnetic field. Coherence transition is very sensitive to the current flowing through the sample, magnetic field and the phase composition and microstructure of the sample. The analysis of superconducting transition by means of the logarithmic derivative of the fluctuation conductivity shows the mesoscopic granularity of the samples.
Źródło:
Acta Physica Polonica A; 2006, 109, 4-5; 485-491
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
MnAs Nanocrystals Embedded in GaAs
Autorzy:
Kwiatkowski, A.
Borysiuk, J.
Bożek, R.
Wasik, D.
Kamińska, M.
Sadowski, J.
Twardowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/2046925.pdf
Data publikacji:
2006-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.46.+w
61.82.Fk
68.37.Rt
68.37.Lp
74.25.Ha
Opis:
We report on cross-sectional transmission electron microscopy and magnetic force microscopy studies performed on self-organized MnAs nanoclusters embedded in GaAs. It was found that 10÷20 nm large MnAs ferromagnetic nanocrystals were formed during rapid thermal annealing of Ga$\text{}_{1-x}$Mn$\text{}_{x}$As layers at 600ºC, leading to magnetic contrasts in magnetic force microscopy images.
Źródło:
Acta Physica Polonica A; 2006, 110, 2; 233-236
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Properties of Short Period InGaMnAs/InGaAs Superlattices
Autorzy:
Sadowski, J.
Mathieu, R.
Svedlindh, P.
Kanski, J.
Karlsteen, M.
Świątek, K.
Domagała, J. Z.
Powiązania:
https://bibliotekanauki.pl/articles/2035614.pdf
Data publikacji:
2002
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.75.+a
75.50.Pp
75.25.+z
Opis:
We have observed a paramagnetic-to-ferromagnetic phase transition in short period InGaMnAs/InGaAs superlattices. The thicknesses of magnetic InGaMnAs layers in the structures studied was chosen to be 4 or 8 molecular layers (12Å or 24Å). The non-magnetic InGaAs spacer layers are 12Å thick. The composition (In content) in InGaMnAs and InGaAs was chosen in such a way that magnetic layers were: deep potential wells, high potential barriers, or shallow potential wells. For superlattices with 8 monolayer thick InGaMnAs magnetic layers and 4 monolayer thick InGaAs non-magnetic spacers the temperatures of paramagnetic-to-ferromagnetic phase transition do not depend on the band offsets between InGaMnAs and InGaAs adjusted by the In content.
Źródło:
Acta Physica Polonica A; 2002, 102, 4-5; 687-694
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Ion Implantation on Magnetic Structural and Optical Properties of (Ga,Mn)As Epitaxial Films
Autorzy:
Yastrubchak, O.
Kulik, M.
Żuk, J.
Domagała, J.
Szymczak, R.
Wosiński, T.
Sadowski, J.
Tóth, A.
Powiązania:
https://bibliotekanauki.pl/articles/1812027.pdf
Data publikacji:
2008-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
78.30.Fs
Opis:
We performed implantation experiments, applying both the chemically active oxygen ions and inactive ions of neon noble gas, to thin epitaxial films of (Ga,Mn)As ferromagnetic semiconductor. Inspection of their magnetic properties by means of a superconducting quantum interference device magnetometer revealed that the implantation with a low dose of either O or Ne ions completely suppressed ferromagnetism in the films. Both the high resolution X-ray diffraction technique and the Raman spectroscopy showed significant changes in the structural and optical properties of the films caused by oxygen implantation and confirmed the preservation of high structural and optical quality of the neon implanted (Ga,Mn)As films.
Źródło:
Acta Physica Polonica A; 2008, 114, 5; 1445-1450
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Solid Phase Epitaxy of Ferromagnetic MnAs Layer and Quantum Dots on Annealed GaMnAs
Autorzy:
Sadowski, J.
Kanski, J.
Adell, M.
Domagała, J. Z.
Janik, E.
Łusakowska, E.
Brucas, R.
Hanson, M.
Powiązania:
https://bibliotekanauki.pl/articles/2044534.pdf
Data publikacji:
2005-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.10.Jt
81.15.Hi
68.65.Hb
68.37.Ps
Opis:
We show that post growth annealing of GaMnAs under As capping at temperatures in the range of 180-210ºC leads to significant surface modifications. Depending on GaMnAs layer thickness and composition, we obtain either a smooth continuous reacted (MnAs) surface layer or 3D islands (quantum dots). The surface modifications are due to a solid phase epitaxial process, in which Mn interstitials diffusing to the GaMnAs surface are bound with the As.
Źródło:
Acta Physica Polonica A; 2005, 108, 5; 851-858
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Photoluminescence Study in PbS-EuS Superlattices
Autorzy:
Kowalczyk, L.
Sadowski, J.
Gałązka, R. R.
Stachow-Wójcik, A.
Sipatov, A. Yu.
Volobuev, V. V.
Smirnov, V. A.
Dugaev, V. K.
Powiązania:
https://bibliotekanauki.pl/articles/1991612.pdf
Data publikacji:
1998-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
Opis:
Investigations of the photoluminescence of PbS-EuS superlattices deposited on (111)BaF$\text{}_{2}$ substrates are presented. Quantum-size and deformation effects in photoluminescence spectra are observed. The strain-induced gap shift and valence-band offset is determined from experimental results. A strong stimulated photoluminescence with relatively low threshold was observed. It was found that the photocarriers generated in EuS barrier strongly affect the population of PbS subbands.
Źródło:
Acta Physica Polonica A; 1998, 94, 3; 397-400
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Defect Structure of High-Temperature-Grown GaMnSb/GaSb
Autorzy:
Romanowski, P.
Bak-Misiuk, J.
Dynowska, E.
Domagala, J.
Sadowski, J.
Wojciechowski, T.
Barcz, A.
Jakiela, R.
Caliebe, W.
Powiązania:
https://bibliotekanauki.pl/articles/1539009.pdf
Data publikacji:
2010-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.05.cp
68.37.Hk
68.49.Sf
68.55.ag
68.55.Ln
Opis:
GaMnSb/GaSb(100) layers with embedded MnSb inclusions have been grown at 720 K using MBE technique. This paper presents the investigation of the defect structure of $Ga_{1-x}Mn_{x}Sb$ layers with different content of manganese (up to x = 0.07). X-ray diffraction method using conventional and synchrotron radiation was applied. Dimensions and shapes of inclusions were detected by scanning electron microscopy. Depth profiles of elements were measured using secondary ion mass spectroscopy technique.
Źródło:
Acta Physica Polonica A; 2010, 117, 2; 341-343
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
MnAs Overlayer on GaN(000$\text{}_{1}$)-(1 x 1) - Its Growth, Morphology and Electronic Structure
Autorzy:
Kowalski, B. J.
Kowalik, I. A.
Iwanowski, R. J.
Łusakowska, E.
Sawicki, M.
Sadowski, J.
Grzegory, I.
Porowski, S.
Powiązania:
https://bibliotekanauki.pl/articles/2038151.pdf
Data publikacji:
2004-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.55.-a
73.20.At
Opis:
MnAs layer has been grown by means of MBE on the GaN(000$\text{}_{1}$)-(1 x 1) surface. Spontaneous formation of MnAs grains with a diameter of 30-60 nm (as observed by atomic force microscopy) occurred for the layer thickness bigger than 7 ML. Ferromagnetic properties of the layer with Curie temperature higher than 330 K were detected by SQUID measurements. Electronic structure of the system was investigated in situ by resonant photoemission spectroscopy for MnAs layer thickness of 1, 2, and 8 ML. Density of the valence band states of MnAs and its changes due to the increase in the layer thickness were revealed.
Źródło:
Acta Physica Polonica A; 2004, 105, 6; 645-650
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
XANES Studies of Mn K and $L_{3,2}$ Edges in the (Ga,Mn)As Layers Modified, by High Temperature Annealing
Autorzy:
Wolska, A.
Lawniczak-Jablonska, K.
Klepka, M.
Jakieła, R.
Demchenko, I.
Sadowski, J.
Holub-Krappe, E.
Persson, A.
Arvanitis, D.
Powiązania:
https://bibliotekanauki.pl/articles/1812244.pdf
Data publikacji:
2008-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Dm
75.50.Pp
Opis:
$Ga_{1-x}Mn_xAs$ is commonly considered as a promising material for microelectronic applications utilizing the electron spin. One of the ways that allow increasing the Curie temperature above room temperature is to produce second phase inclusions. In this paper $Ga_{1-x}Mn_xAs$ samples containing precipitations of ferromagnetic MnAs are under consideration. We focus on the atomic and electronic structure around the Mn atoms relating to the cluster formation. The changes in the electronic structure of the Mn, Ga and As atoms in the (Ga,Mn)As layers after high temperature annealing were determined by X-ray absorption near edge spectroscopy. The experimental spectra were compared with the predictions of ab initio full multiple scattering theory using the FEFF 8.4 code. The nominal concentration of the Mn atoms in the investigated samples was 6% and 8%. We do not observe changes in the electronic structure of Ga and As introduced by the presence of the Mn atoms. We find, in contrast, considerable changes in the electronic structure around the Mn atoms. Moreover, for the first time it was possible to indicate the preferred interstitial positions of the Mn atoms.
Źródło:
Acta Physica Polonica A; 2008, 114, 2; 357-366
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Yb on Valence Band Density of States of CdYbTe and PbYbTe - a Resonant Photoemission Study
Autorzy:
Szamota-Sadowska, K.
Kowalski, B. J.
Guziewicz, E.
Orłowski, B. A.
Sadowski, J.
Gołacki, Z.
Ghijsen, J.
Johnson, R. L.
Belkhou, R.
Radosavkič, D.
Martinotti, D.
Barrett, N.
Guillot, C.
Powiązania:
https://bibliotekanauki.pl/articles/1952185.pdf
Data publikacji:
1996-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.72.Vv
Opis:
Photoemission measurements using synchrotron radiation were performed on PbYbTe (bulk crystal) and CdYbTe (MBE thin film). The resonant enhancement of the photoemission was applied for investigation of the contribution of Yb 4f electrons to the valence band. The set of the energy distribution curves was collected for energies in the region close to the 4d-4f Fano transition. The Yb 4f$\text{}^{14}$ were observed at the binding energies close to the edge of the valence band while the 4f$\text{}^{13}$ states were revealed deep in the valence band.
Źródło:
Acta Physica Polonica A; 1996, 90, 5; 943-946
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-14 z 14

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