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  1. 27 Acta Physica Polonica A

  2. 1 Biuletyn Polskiego Stowarzyszenia Wodoru i Ogniw Paliwowych

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  1. 1 2016

  2. 2 2012

  3. 2 2011

  4. 1 2010

  5. 2 2009

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  1. 28 Dybko K.

  2. 8 Story T.

  3. 8 Szuszkiewicz W.

  4. 8 Witkowska B.

  5. 7 Łusakowska E.

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1
Content available remote

Exchange Integrals in Hg_{0.95}Mn_{0.05}Se Obtained by the Wave Shape Analysis of Shubnikov-de Haas Oscillations

100%
Dybko K., Kossut J.
Acta Physica Polonica A
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1993
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vol. 84
|
issue 4
697-700
EN
The Shubnikov-de Haas oscillations were measured in Hg_{0.95}Mn_{0.05}Se at liquid helium temperatures, in magnetic fields up to 13 tesla. The analysis of the experimental data was performed by means of the wave shape method. The dependence of effective g-factor of the conduction electrons and difference Dingle temperature on magnetic field was determined. Non-zero difference Dingle temperature is a clear evidence of spin dependent scattering in this material. The sp-d exchange constants consistent with extracted spin splitting and difference Dingle temperature, α = -0.39 ± 0.06 eV, β = 0.95 ± 0.07 eV, are in good agreement with the values obtained from magnetooptics.
2
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Reflectivity Study of HgSe_{1-x}Te_{x} Crystals

81%
Kowalski B., Dybko K., Lemańska A., Orłowski B.
Acta Physica Polonica A
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1992
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vol. 82
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issue 5
845-848
EN
The room temperature reflectivity spectra of HgSe_{1-x}Te_{x} (x = 0, 0.4, 0.5, 1.0) crystals were measured in the visible and ultraviolet range from 1.5 to 12 eV. The maxima characteristic of the binary HgA^{IV} compounds can be revealed in the mixed crystals spectra, but their position depends on the crystal composition. There is no duplication of the spectral features in spite of the different energy position of the maxima for HgSe and HgTe. This suggests that the virtual crystal approximation could be used to describe basic optical properties of HgSe_{1-x}Te_{x}.
3
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Zero Field Spin Splitting in GaN/AlGaN Heterostructures Probed by the Weak Antilocalization

81%
Dybko K., Siekacz M., Skierbiszewski C.
Acta Physica Polonica A
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2008
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vol. 114
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issue 5
1109-1113
EN
We present the magnetoconductivity measurements of a high mobility two-dimensional electron gas confined at GaN/AlGaN interface. The sensitive measurements of low field conductivity revealed both quantum corrections, the weak localization and antilocalization effects. It indicates the importance of the spin-orbit coupling in this wide band gap material. The analysis of the data provided the information about the temperature dependence of the dephasing time and total spin-orbit relaxation time. The conduction band spin splitting energy amounts to 0.23 meV and 0.35 meV at electron densities 2.2×10¹² cm¯² and 5.7×10¹² cm¯², respectively.
4
Content available remote

Plasma Edge Modification in Strongly Compensated Semiconductors

81%
Szuszkiewicz W., Dybko K., Bardyszewski W., Julien C.
Acta Physica Polonica A
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1995
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vol. 88
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issue 5
1048-1052
EN
We demonstrate that the electron-impurity interaction can modify the reflectivity in the vicinity of plasma minimum giving rise to a small dip on the plasma edge. Experimental spectra taken for Hg_{1-x}Co_{x}Se for x < 0.02 at various temperatures confirm this theoretical prediction. The position of the structure can be used to determine the plasma frequency in highly compensated materials at low temperatures.
5
Content available remote

Fabrication and Ferroelectric Properties of BiFeO₃/BaTiO₃ Heterostructures

71%
Aleszkiewicz M., Dybko K., Dynowska E., Dluzewski P., Przyslupski P.
Acta Physica Polonica A
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2016
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vol. 130
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issue 2
511-515
EN
We report on preparation and electrical characterization of the epitaxial BaTiO₃ (BTO), BiFeO₃ (BFO) thin films and BFO/BTO bi- and multilayers, grown on (001) SrTiO₃ (STO) and (LaAlO₃)_{0.3}(Sr₂TaAlO₆)_{0.7} (LSAT) substrates. The ferroelectric properties were characterized using the electric force microscopy method to image and switch the electric domains. This fabrication process opens the routes towards wide study of magnetoelectric effect in complex oxide heterostructures.
6
Content available remote

Composition Dependence of the Energy Gap in HgFeSe - Optical Verification

71%
Szuszkiewicz W., Julien C., Bałkanski M., Dybko K., Witkowska B.
Acta Physica Polonica A
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1992
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vol. 82
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issue 5
757-760
EN
Infrared reflectivity was investigated for the mixed Hg_{1-x}Fe_{x}Se crystals for x < 0.1. The theoretical analysis of the experimental curves suggests opening of the energy gap for the composition x = 0.087 at the temperature close to 80 K.
7
Content available remote

New materials for thermoelectric generators based on PbTe-MnTe and PbTe-CdTe semiconductor alloys and nanocomposites

62%
Story T., Dybko K., Dziawa P., Mycielski A., Szczerbakow A., Szot M.
Biuletyn Polskiego Stowarzyszenia Wodoru i Ogniw Paliwowych
|
2011
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issue 6
64-69
EN
New trends in the field of thermoelectrics are discussed for PbTe-based semiconductor thermoelectric materials exhibiting density of states engineering effects strongly enhancing thermoelectric power (PbMnTe) and spontaneous formation of nano-scale two-phase crystal structures (PbTeCdTe) – technologically scalable realization of electron crystal - phonon glass concept of new thermoelectric materials.
8
Publication available in full text mode
Content available

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

62%
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.
9
Content available remote

Electronic Band Structure of Cubic HgS

62%
Guziewicz E., Kowalski B., Orłowski B., Dybko K., Witkowska B., Szuszkiewicz W.
Acta Physica Polonica A
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1995
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vol. 87
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issue 2
395-398
EN
Reflectivity spectra of Hg_{1-x}Fe_{x}S (x < 0.04) and HgSe_{1-y}S_{y} (y < 0.5) mixed crystals were measured in the vacuum ultraviolet energy range from 4 to 12 eV. Information about the electronic band structure of cubic modi­fication of HgS resulting from the above data is analyzed and discussed.
10
Content available remote

Electron-Electron Interaction Effects in Quantum Hall Regime of GaN/AlGaN Heterostructures

62%
Siekacz M., Dybko K., Maude D., Potemski M., Knap W., Skierbiszewski C.
Acta Physica Polonica A
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2007
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vol. 112
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issue 2
269-273
EN
We measured the activation of resistivity at quantum Hall minima in high mobility two-dimensional electron gas confined at AlGaN/GaN interface. The effective g-factor and effective mass was deduced. The electron-electron interactions modify both quantities compared to their bare band values. It is found that the influence of interactions is much more pronounced onto g-factor than effective mass. The relative spin susceptibility was also calculated and compared with available theories. The best agreement was found with the ideal two-dimensional gas model in random phase approximation.
11
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Do the Mixed Crystals HgSeS Exhibit the One-Mode Behavior?

62%
Szuszkiewicz W., Witowski A., Julien C., Balkanski M., Dybko K., Witkowska B., Mycielski A.
Acta Physica Polonica A
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1992
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vol. 82
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issue 5
887-889
EN
The low-temperature far-infrared reflectivity spectra of HgSe and HgSeS are measured and analysed. The results suggest the one-mode behavior of phonon excitations in HgSeS mixed crystals.
12
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Local Modes of Transition Metal Ions (Mn, Fe, Co) in Mercury Chalcogenides

62%
Szuszkiewicz W., Dybko K., Dynowska E., Witkowska B., Jouanne M., Julien C.
Acta Physica Polonica A
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1995
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vol. 88
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issue 5
937-940
EN
Optical phonons in mercury chalcogenides doped with selected transition metal ions are investigated by infrared reflectivity and Raman scattering measurements performed at helium temperatures. The results obtained for Hg_{1-x}Fe_{x}Se, Ηg_{1-x}Co_{x}Se, Ηg_{1-x}Fe_{x}S and Hg_{1-x}Co_{x}S mixed crystals demonstrate the significant influence of the 3d electron correlation effects and/or sp-d hybridization on the transition metal ion local mode frequency.
13
Content available remote

Lattice Dynamics of Cubic Mercury Sulphide

62%
Szuszkiewicz W., Dybko K., Dynowska E., Górecka J., Witkowska B., Hennion B.
Acta Physica Polonica A
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1996
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vol. 90
|
issue 5
947-950
EN
The acoustic phonon dispersion of mercury sulphide of zinc-blende structure (β-HgS) was studied by inelastic neutron scattering. The measurements were carried out at 19 K and 295 K on HgS crystals doped with Fe. A slight decrease in phonon frequencies with increasing temperature was found, the temperature dependence being the strongest for LA phonons with [ξ,ξ,0] propagation. From acoustic phonon dispersion the values of selected elastic constants were determined for β-HgS.
14
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Signature of the Spin Triplet Phase in La_{0.7}Sr_{0.3}MnO_3/Yba_2Cu_3O_7/La_{0.7}Sr_{0.3}MnO_3 Trilayers

62%
Przyslupski P., Dybko K., Werner-Malento K., Aleshkevych P., Wojcik M., Sawicki M.
|
|
issue 2
313-315
EN
Differential dynamical subgap transport measurements were performed on LSMO/YBCO/LSMO trilayers to probe local evolution of the Andreev bound states which are manifested as the zero bias conductance peak. Dynamical conductivity dI/dV vs. magnetic field measured in current in plane and current perpendicular to plane geometries show nonmonotonic behavior with maximum at about 500 Oe. The shape of the zero bias conductance peak measured in current in plane geometry is sharp, whereas zero bias conductance peak measured in current perpendicular to plane geometry demonstrates V shape. These shapes of the zero bias conductance peak were predicted theoretically for unconventional p-wave spin triplet phase superconductor and superconductor with d-wave symmetry of the order parameter, respectively.
15
Publication available in full text mode
Content available

Monocrystalline and Polycrystalline ZnO and ZnMnO Films Grown by Atomic Layer Epitaxy - Growth and Characterization

52%
Wójcik A., Kopalko K., Godlewski M., Łusakowska E., Paszkowicz W., Dybko K., Domagała J., Szczerbakow A., Kamińska E.
Acta Physica Polonica A
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2004
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vol. 105
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issue 6
667-673
EN
Recently we demonstrated growth of monocrystalline ZnO films by atomic layer epitaxy in the gas flow variant using inorganic precursors. In this study, we discuss properties of ZnO films grown with organic precursors. Successful Mn doping of the ZnO films during the growth was achieved using the Mn-thd complex. Secondary ion mass spectroscopy and X-ray investigations reveal the contents of Mn up to about 20% of the cationic component.
16
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Is the Magnetism of HgSe:Fe Clearly Understood?

52%
Dybko K., Łusakowski A., Kossut J., Arciszewska M., Linden P. J. E. M. v., Wittlin A., Perenboom J. A. A. J., Mycielski A.
Acta Physica Polonica A
|
1995
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vol. 87
|
issue 1
193-196
EN
The high magnetic field magnetization measurements of low composition Hg_{1-x}Fe_{x}Se (0.0002 < x < 0.003) at temperatures ranging from 1.6 K to 40 K and in magnetic fields up to 20 T are reported. The magnetization in a sample containing only Fe^{3+} ions (x = 0.0002) is described by the Brillouin function (j = 5/2). The magnetization in the sample codoped with Ga, containing only Fe^{2+} is well described in the model of isolated Fe^{2+} ions. The latter model takes into account the tetrahedral crystal field, the spin-orbit interaction and the Zeeman term. On the other hand, the magnetization of sample with both Fe^{3+} and Fe^{2+} present simultaneously (x = 0.003) is shown to be different from a simple additive superposition of the contributions due to Fe^{3+} and Fe^{2+} subsystems. The possible origin of this discrepancy is discussed.
17
Content available remote

Structure Dependent Conductivity of Ultrathin ZnO Films

52%
Snigurenko D., Kopalko K., Krajewski T., Łuka G., Gierałtowska S., Witkowski B., Godlewski M., Dybko K., Paszkowicz W., Guziewicz E.
Acta Physica Polonica A
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2012
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vol. 122
|
issue 6
1042-1044
EN
Zinc oxide films dedicated for hybrid organic/inorganic devices have been studied. The films were grown at low temperature (100°C, 130C and 200°C) required for deposition on thermally unstable organic substrates. ZnO layers were obtained in atomic layer deposition processes with very short purging times in order to shift a structure of the films from polycrystalline towards amorphous one. The correlation between atomic layer deposition growth parameters, a structural quality and electrical properties of ZnO films was determined.
18
Content available remote

Properties of Fe Doped β-HgS under Hydrostatic Pressure

52%
Szuszkiewicz W., Skierbiszewski C., Paszkowicz W., Dybko K., Domagała J., Dynowska E., Witkowska B., Zinn P.
Acta Physica Polonica A
|
1998
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vol. 94
|
issue 3
570-574
EN
High pressure- high temperature studies of the structural (zinc blende- cinnabar) phase transitions were performed in Hg_{1-x}Fe_{x} S mixed crystals (x<0.1) using synchrotron radiation and multianvil X-ray diffraction press. Pressure investigations of the Hall effect and conductivity of crystals containing up to a few percent of Fe were also performed at 295 K and 77 K. It was demonstrated that Fe in β-HgS creates deep, localized donor state resonant with the conduction band.
19
Content available remote

Electrostatic Gates for GaN/AlGaN Quantum Point Contacts

52%
Czapkiewicz M., Cywiński G., Dybko K., Siekacz M., Wolny P., Gierałtowska S., Guziewicz E., Skierbiszewski C., Wróbel J.
Acta Physica Polonica A
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2012
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vol. 122
|
issue 6
1026-1028
EN
We report on AlGaN/GaN quantum point contacts fabricated by using e-beam lithography and dry ion etching. The tunable nano-constrictions are defined by the integration of side and top gates in a single device. In this configuration, the planar gates are located on the both sides of a quantum channel and the metallic top gates, which cover the active region, are separated from the substrate by an insulating and passivating layers of HfO_2 or Al_2O_3/HfO_2 composite. The properties of devices have been tested at T = 4.2 K. For side gates we have obtained a very small surface leakage current I_g< 10^{-11} A at gate voltages |V_g| < 2 V, however, it is not enough to close the quantum channel. With top gates we have been able to reach the pinch-off voltage at V_g = - 3.5 V at a cost of I_g ≈ 10^{-6} A, which has been identified as a bulk leakage current.
20
Content available remote

Selected Properties of Lattice Dynamics of HgSe and β-HgS

52%
Szuszkiewicz W., Dybko K., Dynowska E., Górecka J., Witkowska B., Hennion B., Jouanne M., Julien C.
Acta Physica Polonica A
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1997
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vol. 92
|
issue 5
1029-1032
EN
Optical phonon dispersion for β-HgS was measured by the neutron scattering for the first time. The results confirmed theoretically predicted anomalous behavior of phonon modes in this material, resulting probably from high ionicity of mercury sulphide and large difference of Hg and S atomic mass. Influence of the isotopic effects on the TO-phonon mode for HgSe and HgS is analyzed. The possible observation of such effects in IR reflectivity spectra taken for HgSe at low temperature is discussed.
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