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Wyszukujesz frazę "Kowalski, G." wg kryterium: Autor


Tytuł:
X-Ray High-Resolution Diffraction and Transmission Topography Study of InGaAs Grown by Liquid Encapsulated Czochralski Technique
Autorzy:
Kowalski, G.
Gronkowski, J.
Borowski, J.
Hruban, A.
Powiązania:
https://bibliotekanauki.pl/articles/1812250.pdf
Data publikacji:
2008-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.72.Dd
07.85.Jy
81.10.Fq
Opis:
New results on ternary InGaAs crystals grown using liquid encapsulated Czochralski technique with constant liquid composition are reported. X-ray high-resolution diffractometry (rocking curves and reciprocal space maps) as well as X-ray topography using the transmission Lang setup were used. Growth history of the bulk ingots was revealed.
Źródło:
Acta Physica Polonica A; 2008, 114, 2; 391-398
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
CVD Growth of Graphene Stacks on 4H-SiC (0001) Surface - X-ray Diffraction and Raman Spectroscopy Study
Autorzy:
Tokarczyk, M.
Kowalski, G.
Grodecki, K.
Urban, J.
Strupiński, W.
Powiązania:
https://bibliotekanauki.pl/articles/1399073.pdf
Data publikacji:
2013-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.48.Gh
61.72.Dd
63.22.Rc
Opis:
Features associated with short and prolonged growth time in the chemical vapor deposition process of growth of graphene stacks on SiC (0001) substrate are reported. In particular general bimodal (as far as $d_{002}$ interlayer spacing is concerned) distribution of graphene species across the surface of the samples is observed. It consists of thin few layer graphene coverage of most of the sample surface accompanied by thick graphite-like island distribution. It points to the two independent channels of graphene stacks growth with two characteristic growth rates.
Źródło:
Acta Physica Polonica A; 2013, 124, 5; 768-771
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Superconductivity Study of GaN Highly Doped by Transition Metals
Autorzy:
Gosk, J.
Boćkowski, M.
Tokarczyk, M.
Kowalski, G.
Twardowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/1399142.pdf
Data publikacji:
2013-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Ha
74.70.-b
74.25.Dw
75.50.-y
61.72.Dd
81.10.Dn
Opis:
GaN:Cr and GaN:Fe single crystals as well as GaN:Mn micropowders highly doped by transition metals were grown to investigate low temperature superconductivity. Magnetic measurements revealed type I superconductivity with $T_{C} ≈ 6 K$ and $H_{C} ≈ 600 Oe$, identical for all compounds and also identical to that observed before in GaP:Cr and GaAs:Cr. The presence of amorphous inclusions of gallium may explain existing superconductivity as a result of a phase transition leading to β-Ga during cooling down of the sample. Since the observed parameters are close to those characteristic for superconducting Ga(II) this possibility could not be ruled out.
Źródło:
Acta Physica Polonica A; 2013, 124, 5; 877-880
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Observation of Magnetic Anisotropy in GaN:Cr Single Crystals
Autorzy:
Gosk, J.
Boćkowski, M.
Kowalski, G.
Grzegory, I.
Szczytko, J.
Twardowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/1403624.pdf
Data publikacji:
2012-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Eq
75.30.Gw
75.50.Pp
75.10.Dg
Opis:
Magnetic properties of bulk wurtzite GaN:Cr single crystals were studied with the magnetic field applied parallel and perpendicular to the crystal wurtzite c-axis. Structure of the crystal was examined by the X-ray diffraction method. Strong anisotropy of magnetization at low temperatures (2-10 K) was observed. The experimental data suggest Cr to be in nonspherical $d^4$ configuration.
Źródło:
Acta Physica Polonica A; 2012, 122, 6; 1007-1009
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Observation of Superconductivity in Highly Cr-Doped GaP Single Crystals
Autorzy:
Gosk, J. B.
Strzelecka, G.
Kowalski, G.
Hruban, A.
Kamińska, M.
Twardowski, A.
Gronkowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/2046913.pdf
Data publikacji:
2006-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.10.+v
75.50.Pp
61.72.Vv
61.72.Dd
81.10.Dn
Opis:
Studying bulk GaP, highly doped with Cr, and searching for possible ferromagnetic semiconductor in view of spintronic applications, we found superconducting behavior of this material unexpectedly. Magnetization techniques and X-ray diffraction were applied to study these crystals. Magnetization revealed superconducting features up to about 6 K and X-ray studies showed that superconductivity might be related to small size Cr precipitates.
Źródło:
Acta Physica Polonica A; 2006, 110, 2; 189-193
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structural and Electronic Properties of Graphene Oxide and Reduced Graphene Oxide Papers Prepared by High Pressure and High Temperature Treatment
Autorzy:
Tokarczyk, M.
Kowalski, G.
Witowski, A.
Koziński, R.
Librant, K.
Aksienionek, M.
Lipińska, L
Ciepielewski, P.
Powiązania:
https://bibliotekanauki.pl/articles/1195411.pdf
Data publikacji:
2014-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.48.Gh
61.72.Dd
63.22.Rc
Opis:
"Graphene paper" prepared by new proprietary method involving high pressure and high temperature treatment in the reduction process show new possibilities in this area. Different phase content: multilayer and single layer graphene stacks recorded in this study for RGO samples are accompanied by the specific electric and optical parameters. We have found that process temperatures above 900°C play crucial role in structural and other properties. For the process temperature around 2000°C we found the onset of the graphitization in the samples.
Źródło:
Acta Physica Polonica A; 2014, 126, 5; 1190-1194
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Properties of Epitaxial Fe/(Ga,Mn)As Hybrids
Autorzy:
Kalbarczyk, K.
Dziatkowski, K.
Szczytko, J.
Gosk, J.
Tokarczyk, M.
Kowalski, G.
Twardowski, A.
Bednarski, W.
Ostrowski, A.
Waplak, S.
Martinek, J.
Liu, X.
Furdyna, J.
Powiązania:
https://bibliotekanauki.pl/articles/1399140.pdf
Data publikacji:
2013-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.75.-c
75.30.Gw
75.50.Pp
75.50.Bb
Opis:
Thin-film structures composed of two kinds of ferromagnetic material - metallic Fe and semiconducting (Ga,Mn)As - were investigated by means of SQUID magnetometry and ferromagnetic resonance spectroscopy. Dependence of remnant magnetic moment on temperature showed unexpected anisotropic features when recorded along two orthogonal in-plane directions. For one of these orientations, the change in sign of the slope of m(T) curve at the Curie point of (Ga,Mn)As was observed, while for the other, an analogous m(T) curve retained monotonic character. Based on the comparison with ferromagnetic resonance data, the apparent non-monotonicity was attributed to the temperature-induced change of balance between the external magnetic field and uniaxial magnetic anisotropy in the plane of Fe layer.
Źródło:
Acta Physica Polonica A; 2013, 124, 5; 873-876
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Swift $Xe^{26+}$ Ion Irradiation Effect on Luminescent Properties of Undoped and Cd-Doped ZnO Films
Autorzy:
Myroniuk, D.
Lashkarev, G.
Shtepliuk, I.
Skuratov, V.
Reszka, A.
Kowalski, B.
Powiązania:
https://bibliotekanauki.pl/articles/1376457.pdf
Data publikacji:
2014-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.55.Et
78.60.Hk
Opis:
Here we report the effect of the irradiation by 167 MeV $Xe^{26+}$ ions (in the fluence range up to 3× $10^{12}$ ions/$cm^2$) on the undoped and Cd-doped (0.4, 0.5 at.%) ZnO films deposited by radiofrequency magnetron sputtering. As-grown and irradiated samples were investigated by cathodoluminescence spectroscopy. It was found that the radiation causes a decrease in intensity of luminescent peaks and a redistribution of the radiative recombination channels. We revealed that the cadmium incorporation into ZnO lattice enhances the radiation resistance of ZnO film.
Źródło:
Acta Physica Polonica A; 2014, 126, 5; 1199-1202
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Critical Behaviour of the Mean-Field Ferromagnet $Cu_{1.02}[Cr_{1.77}Ti_{0.24}]Se_4$
Autorzy:
Krok-Kowalski, J.
Władarz, G.
Rduch, P.
Malicka, E.
Groń, T.
Guzik, A.
Powiązania:
https://bibliotekanauki.pl/articles/1409626.pdf
Data publikacji:
2012-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.40.Cx
75.50.Dd
64.60.Ht
Opis:
Magnetization, M, and susceptibility, χ, measurements showed both strong lowering of magnetic moment in comparison with $CuCr_2Se_4$ matrix and zero-field-cooling-field-cooling susceptibility splitting characteristic for the spin-glass behaviour. Isothermal magnetization curves, M(H), easy saturate and large values both of the Curie $T_{C}$=253 K and Curie-Weiss θ=283.5 K temperatures indicate the ferromagnetic order which coexists with the spin-glass state. The critical behaviour investigated around the paramagnetic-ferromagnetic phase transition revealed that the values of critical exponents are close to those predicted by the mean field model for long-range magnetic interactions.
Źródło:
Acta Physica Polonica A; 2012, 122, 6; 1102-1104
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Cu, Ga and Au Dopants and Technology Conditions on the Magnetic Interactions in $HgCr_2Se_4$ Single Crystals
Autorzy:
Krok-Kowalski, J.
Władarz, G.
Groń, T.
Duda, H.
Pacyna, A.
Nikiforov, K.
Rduch, P.
Powiązania:
https://bibliotekanauki.pl/articles/1493008.pdf
Data publikacji:
2011-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
75.30.Kz
75.30.Et
Opis:
For single crystals $HgCr_2Se_4$ doped by nonmagnetic $Cu^{+},$ $Au^{2+}$ and $Ga^{3+}$ ions and single crystals of $HgCr_2Se_4$ matrix growing in different synthesis conditions both the dc and ac magnetic susceptibility as well as the magnetization have been measured. As it follows from the analysis of the obtained results, paradoxically, the dopants strengthen the long range magnetic interactions of the ferromagnetically ordered single crystals under study, evidenced by the higher values of the ordering temperature in comparison with those ones for pure matrix. An influence of the technological processes connected with deficiency and/or excess of Hg on the long range magnetic interactions was not observed.
Źródło:
Acta Physica Polonica A; 2011, 120, 5; 970-972
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Enhancement of the Ultraviolet Luminescence Intensity from Cd-Doped ZnO Films Caused by Exciton Binding
Autorzy:
Shtepliuk, I.
Lashkarev, G.
Khyzhun, O.
Kowalski, B.
Reszka, A.
Khomyak, V.
Lazorenko, V.
Timofeeva, I.
Powiązania:
https://bibliotekanauki.pl/articles/1492932.pdf
Data publikacji:
2011-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.55.Et
78.67.Bf
81.05.Dz
81.07.Bc
Opis:
ZnO films doped with the cadmium (0.4-0.6%) were grown on crystalline sapphire $c-Al_2O_3$ substrates applying radiofrequency magnetron sputtering at the temperature of 400°C in $Ar-O_2$ atmosphere. The as-grown films were investigated in detail using X-ray diffraction, X-ray photoelectron spectroscopy, and cathodoluminescence spectra. The X-ray diffraction analysis revealed that the films possess a hexagonal wurtzite-type structure with the dominant crystallite orientation along the c axis. It was found that the small concentration of the cadmium significantly enhances the ultraviolet emission associated with excitonic transitions. We suggest that this enhancement effect mainly results from appearance of the cadmium isoelectronic traps, which may bind an exciton, thereby increasing the probability of radiation recombination. The effect of Cd isoelectronic impurity on structural and luminescent properties of ZnO films is discussed.
Źródło:
Acta Physica Polonica A; 2011, 120, 5; 914-917
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Coupling in CuCr$\text{}_{2}$X$\text{}_{4}$ (X = S, Se) Spinel Compounds Obtained via Substitution of the Chromium Ions by Nonmagnetic Sb or Al Ions
Autorzy:
Krok-Kowalski, J.
Malicka, E.
Władarz, G.
Groń, T.
Pawełczyk, M.
Heimann, J.
Pacyna, A. W.
Powiązania:
https://bibliotekanauki.pl/articles/2048127.pdf
Data publikacji:
2011-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
75.30.Kz
75.30.Et
Opis:
Taking into account both the dc magnetic susceptibility and the magnetization measurements as well as the high-temperature expansion of the magnetic susceptibility procedure the hopping integrals and superexchange integrals for the first and second coordination sphere were evaluated. The two hopping integrals are positive and many times greater than the superexchange ones. The obtained results testify to that in the stoichiometric compounds under study the double-exchange magnetic interaction is the main mechanism responsible for very strong, ferromagnetic coupling. Using the total hopping integral B the bandwidth of mixed valence band of chromium ions was determined.
Źródło:
Acta Physica Polonica A; 2011, 119, 5; 705-707
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Substitution of the Chromium Ions by the Nonmagnetic Sb and Al Ions on the Magnetization Processes in $CuCr_{2}X_{4}$ ( rm X = S, Se) Spinels
Autorzy:
Malicka, E.
Krok-Kowalski, J.
Warczewski, J.
Groń, T.
Duda, H.
Mydlarz, T.
Pawełczyk, M.
Pacyna, A.
Rduch, P.
Władarz, G.
Powiązania:
https://bibliotekanauki.pl/articles/1791401.pdf
Data publikacji:
2009-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
75.30.Kz
75.30.Et
Opis:
Both the dc and ac magnetic susceptibilities as well as magnetization measurements were used to study the influence of the dilution of the magnetic chromium subarray by nonmagnetic antimony and aluminium ions on the magnetization processes for four spinel families under investigation. Substitution of the chromium ions by the nonmagnetic Sb and Al ions in the compounds under study leads to the very hard magnetization in the case of the compounds with Sb and very easy magnetization in the compounds with Al. This effect is connected with the electronic configurations of the Sb and Al ions as well as with ionic radii of these cations.
Źródło:
Acta Physica Polonica A; 2009, 116, 5; 967-968
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Elastic Properties of Zinc Blende MnTe
Autorzy:
Djemia, P.
Roussigné, Y.
Stashkevich, A.
Szuszkiewicz, W.
Gonzalez Szwacki, N.
Dynowska, E.
Janik, E.
Kowalski, B. J.
Karczewski, G.
Bogusławski, P.
Jouanne, M.
Morhange, J.
Powiązania:
https://bibliotekanauki.pl/articles/2038250.pdf
Data publikacji:
2004-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
62.20.Dc
75.50.Pp
78.35.+c
Opis:
The Brillouin light scattering was used to investigate elastic properties of the zinc blende, MBE-grown MnTe layer that was deposited on a (001) GaAs substrate covered by CdTe buffer layer. The three elastic constants of the zinc blende MnTe, namely c$\text{}_{11}$, c$\text{}_{12}$, and c$\text{}_{44}$, were directly determined for the first time from the frequency of the Rayleigh mode, of the pseudo-surface mode, and of the shear horizontal bulk mode traveling parallel to the layer surface. The value of c$\text{}_{11}$ was checked using the frequency of longitudinal bulk waves propagating at different angles from the normal of the layer plane. This value was also independently determined by results of the folding of acoustic phonons, observed for MnTe/CdTe superlattices by the Raman scattering. Finally, the bulk modulus given by the formula B=(c$\text{}_{11}$+2c$\text{}_{12}$)/3 was determined for zinc blende MnTe by ab initio calculations making use of the density functional theory and atomic pseudopotentials; spin polarization of MnTe was taken into account. A satisfactory agreement between theoretical and experimental values was obtained.
Źródło:
Acta Physica Polonica A; 2004, 106, 2; 239-247
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Morphology and Selected Properties of Core/Shell ZnTe-Based Nanowire Structures Containing ZnO
Autorzy:
Gas, K.
Janik, E.
Zaleszczyk, W.
Pasternak, I.
Dynowska, E.
Fronc, K.
Kolkovsky, V.
Kret, S.
Morhange, J. F.
Reszka, A.
Wiater, M.
Caliebe, W.
Karczewski, G.
Kowalski, B. J.
Szuszkiewicz, W.
Wojtowicz, T.
Powiązania:
https://bibliotekanauki.pl/articles/2047950.pdf
Data publikacji:
2011-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.37.Hk
68.37.Lp
68.65.La
81.07.Vb
Opis:
We report on an approach to fabricate ZnTe-based core/shell radial heterostructures containing ZnO, as well as on some of their physical properties. The molecular beam epitaxy grown ZnTe nanowires constituted the core of the investigated structures and the ZnO shells were obtained by thermal oxidation of ZnTe NWs. The influence of the parameters characterizing the oxidation process on selected properties of core/shell NWs were examined. Scanning electron microscopy revealed changes of the NWs morphology for various conditions of the oxidation process. X-ray diffraction, high resolution transmission electron microscopy, and Raman scattering measurements were applied to reveal the presence of ZnTe single crystal core and polycrystalline ZnO-shell of investigated structure.
Źródło:
Acta Physica Polonica A; 2011, 119, 5; 612-614
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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