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1
Content available remote

Graphene Conductance in the Presence of Resonant Impurities

100%
Inglot M., Dugaev V.
Acta Physica Polonica A
|
2015
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vol. 128
|
issue 2
163-165
EN
We discuss transport properties of graphene related to the resonant scattering from impurities and defects. Two different models describing defects in the bulk of graphene or at the graphene surface are used for the calculation of self energy of electrons scattered from short-range impurities or defects. The results of numerical calculations demonstrate a resonant character of resistance. In the case of neutral impurities or defects the scattering also leads to a resonant decrease of the spin relaxation time.
2
Content available remote

Electrons in a Semiconductor Quantum Well of the Magnetic Tunneling Structure

100%
Szczepański T., Dugaev V.
Acta Physica Polonica A
|
2015
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vol. 128
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issue 2
222-224
EN
We discuss the properties of resonant tunneling diode with resonant levels in the quantum well. The energy levels are formed inside the well as a consequence of quantization of the states between two potential barriers. We solved the Schrödinger equation for the multilayer structure and found the energy of resonant level as a function of the width of quantum well for different parameters of energy profile in the equilibrium. The results present the dependence of spin splitting in the quantum well of nonmagnetic semiconductor on the spin polarization of electrodes.
3
Content available remote

Absorption of Twisted and Linearly Polarized Light in Graphene with Rashba Spin-Orbit Interaction

100%
Inglot M., Dugaev V.
Acta Physica Polonica A
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2017
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vol. 132
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issue 1
193-195
EN
Theoretical analysis of the electron excitations in graphene on substrate by twisted, linear and circular polarization light is presented. We use a model of graphene with constant Rashba spin-orbit interaction. In this case, the band structure of electrons includes four energy bands. The main objective of this work is to compare light absorptions in graphene for different kinds of light, namely, twisted (with nonzero orbital angular momentum) and linear polarized light. The orbital angular momentum light is characterized by some parameters q and l, which can modify the response, while for the linear polarization, the absorption is modified only in the region determined by the Rashba spin-orbit coupling α.
4
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Indirect Exchange in Band-Inverted Heterojunctions of IV-VI Semimagnetic Compounds

81%
Dugaev V., Litvinov V., Oszwałdowski M.
Acta Physica Polonica A
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1993
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vol. 84
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issue 4
709-712
EN
The interaction of spins localized within the band-inverted heterojunction with the Weyl excitations is shown to differ significantly from the usual s-d interaction. The indirect exchange interaction is long-range and anti-ferromagnetic. The magnitude of interaction decreases with the distance as R^{-3}. The effective interaction depends on the parameters of electron energy spectrum and parameters of the heterojunction as well. It consists of anisotropic Heisenberg term and of pseudodipole terms.
5
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Spin Hall Effect in a Two-Dimensional Electron Gas with Strong Rashba Spin-Orbit Interaction: Semiclassical Keldysh Approach

81%
Dyrdał A., Barnaś J., Ivanov V., Dugaev V.
Acta Physica Polonica A
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2012
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vol. 122
|
issue 6
1059-1061
EN
Spin Hall effect in a two-dimensional electron gas with the Rashba spin-orbit interaction is analyzed theoretically. We use the Keldysh technique for nonequilibrium processes, modified in order to take into account well-defined splitting of the Fermi surface due to strong spin-orbit coupling. Using such an approach, we reconsider the two-dimensional electron gas with the Rashba spin-orbit interaction and show that impurity scattering processes suppress the spin Hall effect.
6
Content available remote

Deformation Potentials in IV-VI Quantum Wells

81%
Litvinov V., Dugaev V., Oszwałdowski M.
Acta Physica Polonica A
|
1995
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vol. 87
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issue 2
345-348
EN
Theoretical studies of the deformation potentials in quantum wells and superlattices are presented. It is shown that a difference exists between the bulk deformation potentials and deformation potentials in the low dimen­sional structures made of narrow-gap semiconductors.
7
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Spin Currents in Magnetic Nanostructures

81%
Dugaev V., Bruno P., Barnaś J.
Acta Physica Polonica A
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2008
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vol. 114
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issue 5
975-982
EN
We discuss some aspects of the problem of spin currents in magnetic nanostructures. One of them is related to the proper definition of the spin current and is generic for any electronic or magnetic system. Using the standard method related to the symmetry with respect to local spin transformations, we analyze the generation of equilibrium spin currents in inhomogeneous magnetic structures. As an example we consider the generation of persistent spin current in a mesoscopic ring.
8
Content available remote

Strain Designed Magnetic Properties of III-V Magnetic Semiconductors

81%
Stagraczyński S., Jasiukiewicz C., Dugaev V., Berakdar J.
Acta Physica Polonica A
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2015
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vol. 128
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issue 2
219-221
EN
We present the theoretical analysis of a possibility of the magnetic anisotropy control using various components of the strain tensor in III-V magnetic semiconductor. We used the Kane model of the valence bands for the numerical simulations of the influence of strain on the Mn doped GaAs valence band structure. Calculating numerically the energy structure of deformed GaMnAs magnetic semiconductor, we also found the total energy of electron system as a function of orientation of the average magnetization vector. Our calculations show how the direction of the magnetization easy axis can be effectively rotated by using different types of deformation.
9
Content available remote

Current-Induced Spin Accumulation and Spin Transfer Torque in a Néel Domain Wall

81%
Baláž P., Szymczyk Ł., Dugaev V., Barnaś J.
Acta Physica Polonica A
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2012
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vol. 121
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issue 5-6
1210-1212
EN
Current-induced spin accumulation in a domain wall and the associated spin torque exerted on the wall are analyzed theoretically. The considerations are limited to a relatively thick Néel domain wall in a bulk ferromagnetic metal. The current-induced spin density is calculated using the linear response theory and the Green function formalism.
10
Content available remote

Effect of Rashba Spin-Orbit Coupling on the Spin Polarization of Holes in Two-Dimensional GaMnAs Magnetic Semiconductors

81%
Stagraczyński S., Dugaev V., Berakdar J.
|
EN
We consider the effect of the Rashba spin-orbital coupling in two-dimensional GaAs semiconductor heavily doped with Mn, on the spin polarization of holes. Due to the strong internal spin-orbit interaction in GaAs, the spin of a hole is not a good quantum number but the hole in some energy state has a certain mean value of spin, which can be strongly affected by the Rashba spin-orbital interaction related to the substrate for 2D material.
11
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Interaction Between Magnetic Layers in Structures with Narrow-Gap IV-VI Semiconductors

81%
Dugaev V., Litvinov V., Dobrowolski W., Story T.
Acta Physica Polonica A
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2000
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vol. 97
|
issue 3
455-458
EN
The results of calculation of the indirect exchange interaction between magnetic layers are presented for the case of a structure with narrow-gap semiconducting IV-VI quantum well. The main mechanism is a magnetic polarization of the size-quantized electrons and holes inside the well. This type of interaction is suggested for the explanation of recent experiments on EuS/PbS structures.
12
Content available remote

Influence of Acoustic Phonons on the Magnetic Anisotropy in GaMnAs Magnetic Semiconductors

71%
Jasiukiewicz C., Stagraczyński S., Lehmann D., Dugaev V., Berakdar J.
Acta Physica Polonica A
|
2015
|
vol. 128
|
issue 2
179-181
EN
We present a theoretical description of the influence of incoherent acoustic phonons on the magnetic anisotropy of magnetic semiconductors. Our theory is based on the six-band Kane model of the electron energy spectrum describing the valence band with k· p Hamiltonian including the hole-phonon interaction term. We include the effect of incoherent phonons through the hole self-energy in the six-band model, and assume a strong laser-pulse-induced flux of non-equilibrium acoustic phonons. The results of numerical calculations of magnetic anisotropy performed for (GaMn)(AsP) magnetic alloy semiconductors demonstrate the essential role of incoherent phonons.
13
Content available remote

The Influence of Electric Field οn the Optical Spin Polarization of Electrons in a Diluted Magnetic Semiconductor

71%
Gorley P., Mysliuk O., Dugaev V., Horley P., Barnaś J.
Acta Physica Polonica A
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2009
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vol. 116
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issue 5
909-910
EN
In this paper we present the results of theoretical calculations for spin polarization η of band electrons in diluted magnetic semiconductor subjected to a polarized light wave and a carrier-warming electric field E. It was shown that the maximum value of η_{max} can be reached at a certain E_{max} corresponding to the peak of the carrier drift velocity v(E). For the higher doping impurity concentration, the values of η_{max} become lower due to the equivalent decrease of electron temperature.
14
Content available remote

Anomalous Hall Effect in IV-VI Semiconductors

71%
Dyrdał A., Dugaev V., Barnaś J., Brodowska B., Dobrowolski W.
Acta Physica Polonica A
|
2009
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vol. 115
|
issue 1
287-289
EN
We consider theoretically the topological contribution to the anomalous Hall effect in narrow-gap IV-VI magnetic semiconductors in which the relativistic terms are relatively large and determine both the non-parabolicity of the energy spectrum and strong spin-orbit interaction. We use the relativistic Dirac model and linear response theory to calculate this contribution. Experimental data on the anomalous Hall effect in these compounds are also presented and discussed.
15
Content available remote

Energy Spectrum in Quantum Dots of Lead and Tin Chalcogenides Semiconducting Compounds

62%
Dugaev V., Litvinov V., Petrov P., Mironov O., Nashchekina O., Oszwałdowski M.
Acta Physica Polonica A
|
1992
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vol. 82
|
issue 5
797-800
EN
The energy spectrum of a quantum dot made from IV-VI narrow gap semiconductors is studied. The calculations of the energy levels as functions of the dot radius are performed. When the anisotropy of the bare energy spectrum is strong, the energy levels are calculated using Fal'kovskii's adiabatic approximation for multiband systems. When the quantum dot material has an inverted band gap with respect to the host, the low-energy states within the fundamental gap are shown to arise.
16
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Content available

Spin Polarized Transport through Quantum Dots: Coulomb Blockade and Kondo Effect

62%
Barnaś J., Świrkowicz R., Wilczyński M., Weymann I., Martinek J., Dugaev V.
Acta Physica Polonica A
|
2003
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vol. 104
|
issue 2
165-177
EN
Spin related effects in electronic transport through quantum dots, coupled via tunneling barriers to two metallic leads, are discussed from the point of view of fundamental physics and possible applications in spin electronics. The effects follow either from long spin relaxation time in the dots or from spin dependent tunneling through the barriers when the external leads are ferromagnetic. In the former case large nonequilibrium spin fluctuations in the dot can be induced by flowing current. These fluctuations modify transport characteristics, particularly the shape of the Coulomb steps. In the latter case electric current depends on magnetic configuration of the system, and tunnel magnetoresistance effect due to magnetization rotation can occur. Transport properties in the weak coupling regime are described perturbatively in the first (sequential) and second (cotunneling) orders. In the strong coupling regime, on the other hand, the equation of motion for nonequilibrium Green functions is used to calculate electric current at low temperatures, where the Kondo peak in conductance is formed in the zero bias regime. In symmetrical systems the Kondo peak is split in the parallel magnetic configuration, whereas no splitting occurs for the antiparallel alignment. Theoretical results are discussed in view of available experimental data.
17
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Charge and Spin Transport in a Metal-Semiconductor Heterostructure with Double Schottky Barriers

62%
Wolski S., Jasiukiewicz C., Dugaev V., Barnaś J., Slobodskyy T., Hansen W.
Acta Physica Polonica A
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2015
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vol. 127
|
issue 2
472-474
EN
Taking into account the available experimental results, we model the electronic properties and current-voltage characteristics of a ferromagnet-semiconductor junction. The Fe/GaAs interface is considered as a Fe/(i-GaAs)/n⁺-GaAs/n-GaAs multilayer structure with the Schottky barrier. We also calculate numerically the current-voltage characteristics of a double-Schottky-barrier structure Fe/GaAs/Fe, which are in agreement with available experimental data. For this structure, we have estimated the spin current in the GaAs layer, which characterizes spin injection from the ferromagnet to the semiconductor.
18
Content available remote

Spin-Dependent Phenomena in Magnetoelectronic Devices

62%
BarnaŚ J., Gmitra M., Rudziński W., Wawrzyniak M., Dugaev V., Kunert H.
Acta Physica Polonica A
|
2007
|
vol. 112
|
issue 6
1259-1265
EN
Spin effects in electronic transport properties of artificial magnetic structures, like nanopillar spin valves, tunnel junctions, mesoscopic double-barrier junctions (single-electron transistors) are briefly discussed. Two classes of spin effects are distinguished; i.e. magnetoresistance phenomena due to magnetization rotation, and current-induced magnetic switching and magnetic dynamics.
19
Content available remote

A Photoluminescence Study in PbS-EuS Superlattices

52%
Kowalczyk L., Sadowski J., Gałązka R., Stachow-Wójcik A., Sipatov A., Volobuev V., Smirnov V., Dugaev V.
Acta Physica Polonica A
|
1998
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vol. 94
|
issue 3
397-400
EN
Investigations of the photoluminescence of PbS-EuS superlattices deposited on (111)BaF_{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.
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