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1
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Transport Relaxation Time of Spin-Polarized Electrons

100%
Paja A., Spisak B.
Acta Physica Polonica A
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2004
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vol. 106
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issue 1
69-76
EN
We study the mechanism of spin relaxation in 3D disordered metallic systems due to the spin-orbit scattering on charged impurities. The transport relaxation time for spin-polarized conduction electrons is calculated analytically in the presented model, where the screened Coulomb potential is used for the description of impurities.
2
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Two-Electron Quantum Dots in Magnetic Field

100%
Adamowski J., Spisak B.
Acta Physica Polonica A
|
1997
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vol. 92
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issue 4
695-698
EN
A theoretical description is given for electronic properties of semiconductor quantum dots in a magnetic field. A two-electron model is applied for electrons in a cylindrical quantum dot with a parabolic confinement potential. The eigenvalue problem is solved by the variational method with the trial wave function proposed in the form of linear combination of S-type and P-type Gaussians. The energy levels of singlet and triplet states with arbitrary radial and magnetic quantum numbers have been calculated as a function of the applied magnetic field. The calculated cyclotron transition energies agree well with those measured for InGaAs/GaAs quantum dots. It is shown that the electron-electron interaction has a small influence on the transition energy.
3
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Electron Transport and Spin Scattering in Very Thin Disordered Metallic Films

100%
Paja A., Spisak B.
Acta Physica Polonica A
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2007
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vol. 112
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issue 6
1289-1295
EN
We consider the electron transport through a very thin disordered metallic film doped with magnetic impurities. We treat the film as a quasi-two-Łinebreak -dimensional system with structural disorder where some ions have spins and other are spinless. The interaction of conduction electrons with localized spins is described by means of the exchange term of the Hamiltonian. The scattering is treated in the first Born approximation and the potential is assumed to be the Coulomb screened one. The total effective cross-section is calculated as a sum of the part responsible for the potential scattering and the second part which comes from the spin-spin scattering. The Fermi sphere splits into separate sheets due to the finite size of the system in the z direction, therefore, the cross-section and the relaxation time are calculated for each sheet independently. The total transport relaxation time and the conductivity are obtained as functions of the thickness of the system and the contents of magnetic impurities. Some model calculations have been made for a thin disordered film of copper doped with manganese.
4
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Influence of Geometric-Confinement Parameters on the Electronic Properties of Quantum Ring

100%
Moskal S., Spisak B.
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EN
We investigate the electronic properties of the quantum rings modelled by a two-dimensional non-singular potential with the cylindrical symmetry as well as the influence of the potential's parameters on energy spectra. In the presence of the external magnetic field we also calculated the persistent currents in such structures in the ballistic regime.
5
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Quantum Kinetic Theory of the '2k_{F}' Scattering Mechanism for Three-Dimensional Structurally Disordered Systems in the Ioffe-Regel limit

100%
Spisak B., Wołoszyn M.
Acta Physica Polonica A
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2015
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vol. 128
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issue 2
213-215
EN
Effect of the coherent backscattering of the conduction electrons in three-dimensional structurally disordered metals specified by the Ioffe-Regel criterion is considered within the framework of the Morgan-Howson-Šaub theory of localisation which is based on the generalised kinetic equation for the Wigner distribution function and effective medium approximation. A formula for the electrical resistivity including the weak localisation correction is expressed in terms of the dimensionless transport parameter k_{F}l. The asymptotic form of the formula is derived and discussed in the context of the diagrammatic approach.
6
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The Effect of Spin-Orbit Scattering on the Electrical Resistivity of Disordered Materials

100%
Spisak B., Paja A.
Acta Physica Polonica A
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1999
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vol. 96
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issue 6
751-758
EN
The spin-orbit scattering of charge carriers is considered as an additional contribution to the potential scattering. The expressions for the effective cross-section and the relaxation time for disordered media are calculated. The results for the Coulomb screened potential are presented and compared with available experimental data.
7
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Transport Characteristics of Gated Core-Multishell Nanowires: Self-Consistent Approach

81%
Palutkiewicz T., Wołoszyn M., Wójcik P., Spisak B.
Acta Physica Polonica A
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2016
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vol. 130
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issue 5
1190-1192
EN
The influence of the applied gate voltage on the coherent propagation of the conduction electrons through the InGaAs/InP core-multishell nanowires with the surrounding gate is considered. The solution of the three-dimensional Schrödinger equation within the effective mass approximation is found using the adiabatic method. The electrostatic potential distribution generated by the all-around gate is determined from the self-consistent procedure applied to the Schrödinger-Poisson problem. The Landauer-Büttiker formalism and quantum transmission boundary method are applied to calculate the transport properties of the considered nanosystem.
8
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Spin-Dependent Transport through Metallic System with Magnetic Impurities

81%
Spisak B., Wołoszyn M., Paja A.
Acta Physica Polonica A
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2009
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vol. 115
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issue 1
266-268
EN
The problem of spin-dependent transport of electrons through a metallic nanostructure is considered. The system consists of non-magnetic metal wire with two magnetic impurities and is connected to two ferromagnetic leads. The differential conductance is calculated by using the transfer matrix method. The spin polarization of the conductance is also obtained. It was found that this polarization is dependent on the spin configuration of magnetic impurities. This dependence can be controlled by the applied bias voltage.
9
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Application of Non-Classical Distribution Function to Transport Properties of Semiconductor Nanodevices

81%
Wójcik P., Spisak B., Wołoszyn M., Adamowski J.
Acta Physica Polonica A
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2008
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vol. 114
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issue 5
1431-1436
EN
The non-classical distribution function formalism is used for studying the electron transport in a nanosystem. We calculated the current-voltage characteristics of a triple barrier one-dimensional nanostructure which is connected to three-dimensional (highly doped semiconductor) reservoirs by the ohmic contacts. We also estimated the peak-to-valley ratio for the considered nanostructure and discussed the effect of switching the bias from peak-to-valley and from valley-to-peak voltages.
10
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Phase-Space Approach to the Position-Momentum Correlations of the Conduction Electron States in a Double-Barrier Resonant Nanosystem

81%
Kaczor U., Wołoszyn M., Spisak B.
Acta Physica Polonica A
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2017
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vol. 132
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issue 1
106-108
EN
The phase-space formulation of quantum mechanics based on the Wigner distribution function is applied to investigate the influence of the scattering processes on the electronic position-momentum correlations in the resonant-tunnelling nanosystem.
11
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Spin Conductance of Nanowires with Double Coupled Quantum Dots

81%
Wołoszyn M., Spisak B., Wójcik P., Adamowski J.
Acta Physica Polonica A
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2016
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vol. 129
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issue 1a
A-114-A-116
EN
Using the computer simulations we have studied the spin conductance of the InAs nanowire with three all-around gates that generate two coupled quantum dots in the nanowire. We have assumed that the same constant voltage is applied to the outermost (left and right) gates and investigated the effect of the varying central-gate voltage (V_{G}) and axially directed magnetic field B on the spin currents. The calculated spin-up and spin-down conductances exhibit pronounced oscillations as functions of V_{G}. In certain intervals of V_{G}, both the spin conductances oscillate in antiphase, which can be applied to the spin-filter operation.
12
Publication available in full text mode
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Phase Space Description of Localization in Disordered One-Dimensional Systems

81%
Wołoszyn M., Spisak B., Maksymowicz A.
Acta Physica Polonica A
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2006
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vol. 110
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issue 4
523-535
EN
The degree of electronic localization in disordered one-dimensional systems is discussed. The model is simplified to a set of Diracδ-like functions used for the potential in the Schrödinger equation and calculations are carried out for the ground state. The disorder of topological character is introduced by the random shifts of the potential peaks. For comparison, we also discuss two aperiodic systems of the potential peaks: Thue-Morse and Fibonacci sequences. The localization, both in the momentum and the real space, is analyzed for different disorder strengths and sizes of the system. We calculate the localization length, and additionally we express the localization effects in terms of the inverse participation function and also by means of the Husimi quasi-classical distribution function in the phase space of the electron (position, momentum) coordinate system. We present the influence of disorder generated by the random and aperiodic sequences of potential on the energy spectrum.
13
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Influence of Dephasing and Geometrical Parameters on Quantum Correction to DC Conductance of Cylindrical Nanowires

81%
Spisak B., Wołoszyn M., Wójcik P.
Acta Physica Polonica A
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2013
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vol. 124
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issue 5
838-840
EN
Calculations of the quantum correction to the DC conductance of a cylindrical nanowire due to the quantum interference are presented. The real space Cooperon equation is solved for cylindrical geometry. Using this approach, it is shown that the quantum correction to the conductance in the weak localisation regime depends not only on the dephasing processes but also on geometrical parameters of the nanowire.
14
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Simulation of Spin-Dependent Electronic Transport through Resonant Tunnelling Diode with Paramagnetic Quantum Well

81%
Wójcik P., Spisak B., Wołoszyn M., Adamowski J.
Acta Physica Polonica A
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2011
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vol. 119
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issue 5
648-650
EN
The spin-dependent electronic transport is investigated in a paramagnetic resonant tunnelling diode formed from Zn_{1 - x}Mn_{x}Se quantum well between two ZnBeSe barrier layers. The spin-dependent current-voltage characteristics have been obtained in the presence of magnetic fields by solving the quantum kinetic equation for the Wigner distribution function and the Poisson equation in the self-consistent procedure. We have obtained two distinct current peaks due to the giant Zeeman splitting of electronic levels in a qualitative agreement with experiment. We have shown that the sign of spin current polarization can be reversed by tuning the bias voltage. Moreover, we have found the bias voltage windows with a nearly constant polarization.
15
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Influence of Geometrical Parameters on the Transport Characteristics of Gated Core-Multishell Nanowires

71%
Palutkiewicz T., Wołoszyn M., Wójcik P., Adamowski J., Spisak B.
Acta Physica Polonica A
|
2016
|
vol. 129
|
issue 1a
A-111-A-113
EN
Calculations of the current-voltage characteristics of the core-multishell nanowires for different radii of the core and various thicknesses of the shells are presented. A role of the conducting core and shells in the coherent transport under the influence of the gate voltage is discussed.
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