Search results

1

Pb_{1-x}Mn_xTe Crystals as a New Thermoelectric Material

100%

Osinniy V., Jędrzejczak A., Domuchowski W., Dybko K., Witkowska B., Story T.

Acta Physica Polonica A

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2005

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vol. 108

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issue 5

809-816

EN

We studied experimentally thermoelectric properties of p-type bulk crystals of Pb_{1-x}Mn_xTe and Pb_{1-x-y}Ag_yMn_xTe (0≤ x≤ 0.083 and y≤0.017) at room and liquid nitrogen temperatures. Model calculations of the thermoelectric figure of merit parameter (Z) involved the analysis of carrier concentration, carrier mobility, density of states as well as electronic and lattice contributions to the thermal conductivity of PbMnTe. In the analysis we took into account the main effect of Mn concentration on the band structure parameters of PbMnTe, i.e. the increase of the energy gap. The analysis of electrical, thermoelectric, and thermal properties of Pb_{1-x}Mn_xTe crystals showed that, at room temperature, the maximum values of the parameter Z occur in crystals with Mn content 0.05≤ x≤0.07 and are comparable with a maximal value of Z observed in PbTe. At T=400 K the increase in the parameter Z by 10% is expected in Pb_{1-x}Mn_xTe crystal (as compared to PbTe) for a very high concentration of holes of about p=5×10^{19} cm^{-3}. The experimental data correctly reproduce the theoretical Z(p) dependence.

2

Fermi Level Position in GaMnAs - a Thermoelectric Study

100%

Osinniy V., Jędrzejczak A., Arciszewska M., Dobrowolski W., Story T., Sadowski J.

Acta Physica Polonica A

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2001

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vol. 100

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issue 3

327-334

EN

Thermoelectric power was studied in the temperature range 100≤ T≤300 K in 0.3-1μm thick ferromagnetic Ga_{1-x}Mn_xAs epitaxial layers (0.015≤ x≤0.06) in order to determine Fermi energy E_F and carrier concentration p. For 0.015≤ x≤0.05, at T=273 K we find E_F=275±50 meV and p=(2.5± 0.5)×10^{20} cm^{-3} (approximately Mn content independent). For x= 0.06, the Fermi energy decreases by about 100 meV with the corresponding reduction of hole concentration to p=1.2×10^{20} cm^{-3}. At T=120 K, these parameters vary between E_F=380 meV and p=3.5×10^{20} cm^{-3} for x=0.015 to E_F=110 meV and p=5×10^{19} cm^{-3} for x=0.06.

3

The Surface Hydro-Oxidation of LaNiO_{3-x} Thin Films

84%

Mickevičius S., Grebinskij S., Bondarenka V., Lisauskas V., Šliužienė K., Tvardauskas H., Vengalis B., Orłowski B., Osinniy V., Drube W.

Acta Physica Polonica A

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2007

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vol. 112

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issue 1

113-120

EN

The high-energy X-ray photoelectron spectroscopy was used to determine the composition and chemical structure of epitaxial LaNiO_{3-x} films obtained by a reactive dc magnetron sputtering. It was found that the oxide and hydroxide species of La and Ni are on the films surface. The thickness of hydroxide enriched layer, estimated from the oxide and hydroxide peak intensities, is about 2 nm.

4

Fano Resonance of Eu^{2+} and Eu^{3+} in (Eu,Gd)Te MBE Layers

84%

Orlowski B., Kowalski B., Dziawa P., Pietrzyk M., Mickievicius S., Osinniy V., Taliashvili B., Kowalik I., Story T., Johnson R.

Acta Physica Polonica A

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2005

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vol. 108

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issue 5

803-807

EN

Resonant photoemission spectroscopy, with application of synchrotron radiation, was used to study the valence band electronic structure of clean surface of (EuGd)Te layers. Fano-type resonant photoemission spectra corresponding to the Eu 4d-4f transition were measured to determine the contribution of 4f electrons of Eu^{2+} and Eu^{3+} ions to the valence band. The resonant and antiresonant photon energies of Eu^{2+} ions were found as equal to 141 V and 132 eV, respectively and for Eu^{3+} ions were found as equal to 146 eV and 132 eV, respectively. Contribution of Eu^{2+}4f electrons was found at the valence band edge while for Eu^{3+} it was located in the region between 3.5 eV and 8.5 eV below the valence band edge.

5

Photoemission Study of Mn 3d Electrons in the Valence Band of Mn/GeMnTe

84%

Pietrzyk M., Kowalski B., Orłowski B., Knoff W., Osinniy V., Kowalik I., Story T., Johnson R.

Acta Physica Polonica A

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2007

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vol. 112

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issue 2

275-281

EN

We present the results of the electronic band structure study of Ge_{0.9}Mn_{0.1}Te epilayers, clean and modified in situ by deposition of manganese atoms. The sets of resonant photoemission spectra were measured for the photon energy range covering the energy of Mn 3p→3d transition (45

6

Fano Resonance Investigation of PbTe Layers Containing Eu and Gd Ions

84%

Orlowski B., Osinniy V., Dziawa P., Pietrzyk M., Kowalski B., Taliashvili B., Story T., Johnson R.

Acta Physica Polonica A

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2008

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vol. 114

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issue 2

351-356

EN

The Fano resonance photoemission studies of Gd/(Pb, Gd)Te layers using synchrotron radiation were carried out and the electronic structure parameters like binding energies of Gd^{3+} 4f and 5p shells, resonance and antiresonance energies for Gd^{3+} were determined. The presence of Eu^{3+} ions was observed in the (Pb, Eu)Te and (Eu, Gd)Te layers grown by MBE technique. The comparison of data for (Pb, Gd)Te compound with corresponding data for (Eu, Gd)Te and (Pb, Eu)Te layers indicates that we are not able to distinct the Eu^{3+}4f and Gd^{3+}4f electrons contribution to the valence band photoemission spectra because of small content od Gd and similar binding energy values. The key parameters allowing to prove exactly the presence of either Eu^{3+} or Gd^{3+} are the resonance and antiresonance energies which are significantly different for these ions and equal to 143 eV/137 eV and 150 eV/142 eV, respectively.

7

Interlayer Exchange Coupling in Semiconductor EuS-PbS Ferromagnetic Wedge Multilayers

84%

Kowalczyk L., Wrotek S., Dziawa P., Osinniy V., Szot M., Story T., Sipatov A., Volobuev V., Fedorov A.

Acta Physica Polonica A

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2006

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vol. 110

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issue 2

225-231

EN

Antiferromagnetic interlayer coupling between ferromagnetic layers of EuS via nonmagnetic PbS spacer layer was experimentally studied in EuS-PbS wedge multilayers grown on KCl (001) substrates with EuS thickness of 6 nm and PbS thickness varying in the wedges in the range 0.3-6 nm (i.e. n=1-20 monolayers). Measurements of magnetic hysteresis loops of EuS-PbS multilayers performed in the temperature range 5-30 K by superconducting (SQUID) and magneto-optical magnetometers revealed a rapid increase in saturation magnetic field in multilayers with PbS spacer thinner than about 1.5 nm. It shows a monotonic increase in interlayer coupling strength with a decreasing PbS spacer thickness, in qualitative agreement with 1/2^n dependence predicted theoretically for semiconductor magnetic superlattices.

8

(Eu,Gd)Te - MBE Growth and Characterization

69%

Dziawa P., Taliashvili B., Domuchowski W., Łusakowska E., Arciszewska M., Demchenko I., Dobrowolski W., Dybko K., Fedorych O., Nadolny A., Osinniy V., Petrouchyk A., Story T.

Acta Physica Polonica A

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2004

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vol. 106

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issue 2

215-221

EN

Monocrystalline thin layers of (Eu,Gd)Te, n-type ferromagnetic semiconductor, were grown by molecular beam epitaxy technique on BaF_2 (111) substrates. Reflection high-energy electron diffraction, X-ray diffraction, and atomic force microscopy characterization proved epitaxial mode of growth and high crystal quality of the layers. Magnetic susceptibility and magnetic resonance measurements showed that in (Eu,Gd)Te layers ferromagnetic transition takes place at about 13 K. Electrical characterization carried out by the Hall effect and resistivity measurements revealed very high electron concentration of 10^{20}~cm^{-3} and sharp maximum of resistivity at transition temperature.

9

Valence States of Metal Ions in La_{0.7}Ce_{0.3}MnO_3 Thin Films

69%

Mickevičius S., Bondarenka V., Grebinskij S., Oginskis A., Butkutė R., Tvardauskas H., Vengalis B., Orlowski B., Osinniy V., Pietrzyk M., Drube W.

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EN

We report valence states of ions in La_{0.7}Ce_{0.3}MnO_3 thin films grown by a reactive dc magnetron sputtering. The measurements were performed by means of high-energy X-ray photoelectron spectroscopy using synchrotron radiation. It was found that Ce ion in the compound is either in tetravalent or trivalent chemical state, manganese is in divalent, trivalent and tetravalent states, while La ion existing in oxide and hydroxide chemical species is in trivalent state.

10

Extra-Low Temperature Growth of ZnO by Atomic Layer Deposition with Diethylzinc Precursor

69%

Kowalik I., Guziewicz E., Kopalko K., Yatsunenko S., Godlewski M., Wójcik A., Osinniy V., Krajewski T., Story T., Łusakowska E., Paszkowicz W.

Acta Physica Polonica A

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2007

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vol. 112

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issue 2

401-406

EN

ZnO thin films were grown on silicon substrate by atomic layer deposition method. We explored double-exchange chemical reaction and used very volatile and reactive diethylzinc as a zinc precursor. These enables us to obtain zinc oxide thin films of high quality at extremely low growth temperature (90-200ºC). The films are polycrystalline as was determined by X-ray diffraction and show flat surfaces with roughness of 1-4 nm as derived from atomic force microscopy measurements. Photoluminescence studies show that an edge emission of excitonic origin is observed even at room temperature for all investigated ZnO layers deposited with the diethylzinc precursor.

11

Magnetic Properties of EuS-SrS Semiconductor Multilayer Structures

69%

Szot M., Kowalczyk L., Deptuła P., Domukhovski V., Osinniy V., Smajek E., Szczerbakow A., Sipatov A., Volobuev V., Fedorov A., Story T.

Acta Physica Polonica A

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2007

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vol. 112

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issue 2

419-424

EN

Magnetic and structural properties of EuS-SrS semiconductor multilayers were studied by SQUID and magneto-optical Kerr effect magnetometry techniques and by X-ray diffraction method. The multilayers composed of monocrystalline, lattice matched ferromagnetic EuS layers (thickness 35-50Å) and nonmagnetic SrS spacer layers (thickness 45-100Å) were grown epitaxially on KCl (001) substrates with PbS buffer layer. Ferromagnetic transition in EuS-SrS multilayers was found at the Curie temperature T_c=17 K. The multilayers exhibit only weak in-plane magnetic anisotropy with [110] easy magnetization axis. Coercive field of EuS-SrS multilayers shows a linear increase with decreasing temperature. Magneto-optical mapping of magnetic hysteresis loops of the multilayers revealed good spatial homogeneity of their magnetic properties.

Refine search results

Pb_{1-x}Mn_xTe Crystals as a New Thermoelectric Material

Fermi Level Position in GaMnAs - a Thermoelectric Study

The Surface Hydro-Oxidation of LaNiO_{3-x} Thin Films

Fano Resonance of Eu^{2+} and Eu^{3+} in (Eu,Gd)Te MBE Layers

Photoemission Study of Mn 3d Electrons in the Valence Band of Mn/GeMnTe

Fano Resonance Investigation of PbTe Layers Containing Eu and Gd Ions

Interlayer Exchange Coupling in Semiconductor EuS-PbS Ferromagnetic Wedge Multilayers

(Eu,Gd)Te - MBE Growth and Characterization

Valence States of Metal Ions in La_{0.7}Ce_{0.3}MnO_3 Thin Films

Extra-Low Temperature Growth of ZnO by Atomic Layer Deposition with Diethylzinc Precursor

Magnetic Properties of EuS-SrS Semiconductor Multilayer Structures