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1
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Microhardness and the Young Modulus of Thin, MBE-Grown, (Sn,Mn)Te Layers Containing up to 8% of Mn

100%
Adamiak S., Zięba M., Minikayev R., Reszka A., Taliashvili B., Szuszkiewicz W.
Acta Physica Polonica A
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2017
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vol. 132
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issue 2
347-350
EN
The thin layers of (Sn,Mn)Te solid solution were grown by molecular beam epitaxy onto (111)-oriented BaF₂ substrates and characterized by scanning electron microscopy, atomic force microscopy, energy dispersive X-ray spectrometry, and X-ray diffraction methods. The epitaxial character of the growth was confirmed. All the layers exhibited a regular (fcc) structure of the rock-salt type and were (111)-oriented, their thickness was close to about 1 μm. The layers contained up to 8% of Mn. The microhardness and the Young modulus values were determined by the nanoindentation measurements. The Berkovich type of the intender was applied, the maximum applied load was equal to 1 mN. The results of measurements demonstrated a lack of the composition dependence of the Young modulus value. A slight increase of the microhardness value with an increasing Mn content in the (Sn,Mn)Te solid solution was observed.
2
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Photoemission Electronic Spectra οf CdTe/Pb_{0.95}Eu_{0.05}Te/CdTe

100%
Orlowski B., Dziawa P., Gas K., Reszka A., Mickievicius S., Thiess S., Drube W.
Acta Physica Polonica A
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2011
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vol. 120
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issue 5
960-963
EN
The synchrotron radiation was used to apply tunable high energy X-ray photoemission spectroscopy for investigation of electronic structure of semiconductor nanostructure CdTe/Pb_{0.95}Eu_{0.05}Te/CdTe/GaAs(001) top part. The Pb_{0.95}Eu_{0.05}Te (6 nm thick) was buried under thin (22 nm) top layer of CdTe transparent for part of electrons photoemitted from Pb_{0.95}Eu_{0.05}Te buried layer. The top layer of CdTe was sputtered by Ar ion bombardment for surface cleaning and for leaving the thickness of CdTe more transparent for photoelectrons emitted from buried layer. For these thickness of the top layer the photoemission energy distribution curves corresponding to the valence band and core levels electrons of the buried layer atoms were measured with application of synchrotron radiation of energy hν = 3510 eV. The measured spectra corresponding to the buried layer atoms were observed in the valence band region and in the high binding energy region for core levels of Pb 4f, Pb 3d. The valence band contribution and core levels Cd 4d and Cd 3d were obtained mainly from top cover layer. Measured Te 4d, Te 3d and Te 4d spectra possess contribution as well from top cover layer as from the buried layer. The amount of Eu atoms was to small to be reasonable detected and presented in the paper.
3
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Swift Xe^{26+} Ion Irradiation Effect on Luminescent Properties of Undoped and Cd-Doped ZnO Films

100%
Myroniuk D., Lashkarev G., Shtepliuk I., Skuratov V., Reszka A., Kowalski B.
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vol. 126
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issue 5
1199-1202
EN
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.
4
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Magnetic Properties of Sn_{1-x}Cr_xTe Diluted Magnetic Semiconductors

84%
Kilanski L., Podgórni A., Górska M., Dobrowolski W., Slynko V., Slynko E., Reszka A., Kowalski B.
Acta Physica Polonica A
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2013
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vol. 124
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issue 5
881-884
EN
We present the studies of Sn_{1-x}Cr_xTe semimagnetic semiconductors with chemical composition x ranging from 0.004 to 0.012. The structural characterization indicates that even at low average Cr-content x ≤q 0.012, the aggregation into micrometer size clusters appears in our samples. The magnetic properties are affected by the presence of clusters. In all our samples we observe the transition into the ordered state at temperatures between 130 and 140 K. The analysis of both static and dynamic magnetic susceptibility data indicates that the spin-glass-like state is observed in our samples. The addition of Cr to the alloy seems to shift the spin-glass-like transition from 130 K for x = 0.004 to 140 K for x = 0.012.
5
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Enhancement of the Ultraviolet Luminescence Intensity from Cd-Doped ZnO Films Caused by Exciton Binding

84%
Shtepliuk I., Lashkarev G., Khyzhun O., Kowalski B., Reszka A., Khomyak V., Lazorenko V., Timofeeva I.
Acta Physica Polonica A
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2011
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vol. 120
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issue 5
914-917
EN
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.
6
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Anomalous Hall Effect in Ge_{1-x-y}Pb_{x}Mn_{y}Te Composite System

84%
Podgórni A., Kilanski L., Dobrowolski W., Górska M., Domukhovski V., Brodowska B., Reszka A., Kowalski B., Slynko V., Slynko E.
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vol. 126
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issue 5
1180-1183
EN
The purpose of this study was to investigate the magnetotransport properties of the Ge_{0.743}Pb_{0.183}Mn_{0.074}Te mixed crystal. The results of magnetization measurements indicated that the compound is a spin-glass-like diluted magnetic semiconductor with critical temperature T_{SG}=97.5 K. Nanoclusters in the sample are observed. Both, matrix and clusters are magnetically active. Resistivity as a function of temperature has a minimum at 30 K. Below the minimum a variable-range hopping is observed, while above the minimum a metallic-like behavior occurs. The crystal has high hole concentration, p=6.6×10^{20} cm^{-3}, temperature-independent. Magnetoresistance amplitude changes from -0.78 to 1.18% with increase of temperature. In the magnetotransport measurements we observed the anomalous Hall effect with hysteresis loops. Calculated anomalous Hall effect coefficient, R_{S} = 2.0×10^{6} m^{3}/C, is temperature independent. The analysis indicates the extrinsic skew scattering mechanism to be the main physical mechanism responsible for anomalous Hall effect in Ge_{0.743}Pb_{0.183}Mn_{0.074}Te alloy.
7
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Spinodal Decomposition of Magnetic Ions in Eu-Codoped Ge_{1-x}Cr_{x}Te

69%
Podgórni A., Kilanski L., Dobrowolski W., Górska M., Reszka A., Domukhovski V., Kowalski B., Brodowska B., Anderson J., Butch N., Slynko V., Slynko E.
Acta Physica Polonica A
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2012
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vol. 122
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issue 6
1012-1015
EN
We present the experimental evidence for the presence of spinodal decomposition of the magnetic ions in the Ge_{1-x-y}Cr_{x}Eu_{y}Te samples with chemical composition varying in the range of 0.015 ≤ x ≤ 0.057 and 0.003 ≤ y ≤ 0.042. The ferromagnetic transition at temperatures 50 ≤ T ≤ 57 K was observed, independent of the chemical composition. The long-range carrier mediated itinerant magnetic interactions seem to be responsible for the observed ferromagnetic order. The magnetic irreversibility with coercive field H_C = 5 - 63 mT and the saturation magnetization M_S ≈ 2 - 6 emu/g are found to strongly depend on the chemical composition of the alloy.
8
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Morphology and Selected Properties of Core/Shell ZnTe-Based Nanowire Structures Containing ZnO

69%
Gas K., Janik E., Zaleszczyk W., Pasternak I., Dynowska E., Fronc K., Kolkovsky V., Kret S., Morhange J., Reszka A., Wiater M., Caliebe W., Karczewski G., Kowalski B., Szuszkiewicz W., Wojtowicz T.
Acta Physica Polonica A
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2011
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vol. 119
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issue 5
612-614
EN
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.
9
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Ferromagnetic Transition in Ge_{1-x}Mn_{x}Te Layers

69%
Knoff W., Domukhovski V., Dybko K., Dziawa P., Jakieła R., Łusakowska E., Reszka A., Świątek K., Taliashvili B., Story T., Szałowski K., Balcerzak T.
Acta Physica Polonica A
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2009
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vol. 116
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issue 5
904-906
EN
Ferromagnetic transition temperature in thin layers of diluted magnetic (semimagnetic) semiconductor Ge_{1-x}Mn_{x}Te was studied experimentally by SQUID magnetometry method and analyzed theoretically for a model Ising-type diluted magnetic system with Ruderman-Kittel-Kasuya-Yosida indirect exchange interaction. The key features of the experimentally observed dependence of the Curie temperature on Mn content (x ≤ 0.12) and conducting hole concentration p = (1-10) × 10^{21} cm^{-3} were reproduced theoretically for realistic valence band and crystal lattice parameters of p-Ge_{1-x}Mn_{x}Te taking into account short carrier mean free path encountered in this material and Ruderman-Kittel-Kasuya-Yosida mechanism with both delta-like and diffused character of spatial dependence of the exchange coupling between magnetic ions and free carriers.
10
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Magnetic Properties of Epitaxial (Ge,Mn)Te Thin Films with Varying Crystal Stoichiometry

69%
Knoff W., Domukhovski V., Dybko K., Dziawa P., Górska M., Jakieła R., Łusakowska E., Taliashvili B., Story T., Reszka A., Anderson J., Rotundu C.
Acta Physica Polonica A
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2008
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vol. 114
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issue 5
1159-1165
EN
Magnetization of 1 μm thick ferromagnetic IV-VI (Ge, Mn)Te semiconductor layers with 10 at.% of Mn was studied by SQUID magnetometry method up to the magnetic fields of 70 kOe. The layers were grown on BaF₂ (111) substrates by molecular beam epitaxy with varying Te molecular flux, which permitted the control of layer stoichiometry and conducting hole concentration. X-ray diffraction and in situ electron diffraction characterization of layer growth and crystal structure revealed two-dimensional mode of growth and monocrystalline rhombohedral crystal structure of (Ge, Mn)Te layers. Controlling the layer stoichiometry influences the temperature dependence of magnetization with the ferromagnetic Curie temperature varying in Ge_{0.9}Mn_{0.1}Te layers from T_c=30 K (low Te flux) to T_c=42 K (high Te flux).
11
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Magnetic Order and Magnetic Inhomogeneities in SnCrTe-PbCrTe Solid Solutions

69%
Kilanski L., Szymański M., Brodowska B., Górska M., Szymczak R., Podgórni A., Avdonin A., Reszka A., Kowalski B., Domukhovski V., Arciszewska M., Dobrowolski W., Slynko V., Slynko E.
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vol. 126
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issue 5
1203-1206
EN
We present the studies of structural, electrical and magnetic properties of bulk Sn_{1-x-y}Pb_xCr_yTe mixed crystals with chemical composition 0.18 ≤ x ≤ 0.35 and 0.007 ≤ y ≤ 0.071. The magnetometric studies indicate that for the high Cr-content, y=0.071, the alloy shows ferromagnetic alignment with the Curie temperature, T_{C}, around 265 K. The Cr_5Te_8 clusters are responsible for the ferromagnetic order. At low Cr content, y ≈ 0.01, a peak in the ac magnetic susceptibility identified as the cluster-glass-like transition is observed at a temperature about 130 K. The cluster-glass-like transition is likely due to the presence of Cr_2Te_3 clusters in the samples with y ≈ 0.01. The transport characterization of the samples indicated strong metallic p-type conductivity with relatively high carrier concentration, n > 10^{20} cm^{-3}, and carrier mobility, μ > 150 cm^2/(V s).
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