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Wyszukujesz frazę "73.23.-b" wg kryterium: Temat


Wyświetlanie 1-10 z 10
Tytuł:
Coherent Transport through Systems of Coupled Quantum Dots
Autorzy:
Trocha, P.
Barnaś, J.
Powiązania:
https://bibliotekanauki.pl/articles/2047730.pdf
Data publikacji:
2007-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.23.-b
73.21.La
73.23.Hk
Opis:
Spin-dependent electronic transport through two coupled single-level quantum dots attached to ferromagnetic leads with parallel and antiparallel magnetizations is analyzed theoretically. The intra-dot Coulomb correlation is taken into account, while the inter-dot Coulomb repulsion is omitted. Conductance and tunnel magnetoresistance associated with magnetization rotation are calculated by the nonequilibrium Green function technique. The relevant Green functions are derived by the equation of motion method in the Hartree-Fock approximation. The dot occupation numbers and the Green functions are calculated self-consistently. The interference effects in electronic transport through quantum dots are analyzed in two different configurations. It is shown that the Fano resonance in conductance can be observed even for vanishing inter-dot hopping parameter t. The interplay of the interference effects and the Coulomb interactions in quantum dots is also analyzed.
Źródło:
Acta Physica Polonica A; 2007, 112, 2; 473-480
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin Thermoelectric Effects in Transport through a Two-Level Quantum Dot Coupled to Ferromagnetic Leads
Autorzy:
Karwacki, Ł.
Trocha, P.
Barnaś, J.
Powiązania:
https://bibliotekanauki.pl/articles/1427587.pdf
Data publikacji:
2012-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.21.La
73.23.-b
73.63.Kv
73.50.Lw
Opis:
We investigate spin thermoelectric effects in a two-level quantum dot attached to external ferromagnetic leads. The basic thermoelectric coefficients are calculated by means of the non-equilibrium Green functions approach in the mean field approximation for the Coulomb term. Specifically, we calculate spin-dependent thermopower (spin Seebeck coefficient) and the charge thermopower. These coefficients measure spin and charge voltage drops across the device, respectively. Moreover, the figure of merit and its spin analog (which measures the spin thermoelectric efficiency) are presented and discussed. We also show that the indirect (via the leads) coupling between the dot's levels can significantly enhance the thermoelectric effects.
Źródło:
Acta Physica Polonica A; 2012, 121, 5-6; 1207-1209
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermoelectric and Interference Effects in a Kondo-Correlated Quantum Dot with Rashba Spin-Orbit Coupling
Autorzy:
Karwacki, Ł.
Trocha, P.
Barnaś, J.
Powiązania:
https://bibliotekanauki.pl/articles/1399158.pdf
Data publikacji:
2013-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.23.-b
73.63.Kv
72.15.Qm
85.35.Ds
Opis:
Thermoelectric effects in spin-polarized transport through a strongly correlated quantum dot coupled to two ferromagnetic leads is investigated theoretically by means of the finite-U slave boson technique. The dot is coupled to the leads both symmetrically via the spin-conserving tunneling processes and asymmetrically via spin-nonconserving Rashba-induced tunneling terms. The asymmetric coupling leads to various interference effects which modify transport properties. We have analyzed such thermoelectric coefficients like the electronic contribution to heat conductance κ, thermopower S, and thermoelectric efficiency ZT.
Źródło:
Acta Physica Polonica A; 2013, 124, 5; 901-904
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin and Charge Transport in a Magnetic Tunnel Junction with Magnetic Impurities Embedded in the Tunnel Barrier
Autorzy:
Misiorny, M.
Barnaś, J.
Powiązania:
https://bibliotekanauki.pl/articles/1402573.pdf
Data publikacji:
2015-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.10.Fk
72.25.-b
73.23.-b
75.50.Xx
Opis:
Electronic transport in a nanoscopic magnetic tunnel junction with magnetic particles or magnetic impurity atoms/molecules embedded in the barrier is studied theoretically. The impurity Hamiltonian includes magnetic anisotropy of easy axis type with additional perpendicular term. The description takes into account both elastic tunneling processes as well as inelastic processes associated with a flip of electron spin.
Źródło:
Acta Physica Polonica A; 2015, 128, 2; 196-199
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Signatures of Transverse Magnetic Anisotropy in Transport through a Large-Spin Molecule in the Kondo Regime
Autorzy:
Misiorny, M.
Weymann, I.
Barnaś, J.
Powiązania:
https://bibliotekanauki.pl/articles/1402574.pdf
Data publikacji:
2015-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.10.Fk
72.25.-b
73.23.-b
75.50.Xx
Opis:
The effect of transverse magnetic anisotropy on spin-dependent transport through a large-spin molecule strongly tunnel-coupled to ferromagnetic electrodes is analyzed theoretically. In particular, we investigate whether it is possible to observe in transport signatures of oscillations of the ground-state doublet splitting due to the application of an external magnetic field along the molecule's hard axis. We show that magnetic field leads to revivals of the Kondo effect, with the Kondo temperature depending on the magnetic configuration of the device.
Źródło:
Acta Physica Polonica A; 2015, 128, 2; 200-203
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Phonon-Assisted Kondo Resonance in Spin-Dependent Transport through a Quantum Dot
Autorzy:
Świrkowicz, R.
Wilczyński, M.
Barnaś, J.
Powiązania:
https://bibliotekanauki.pl/articles/1810522.pdf
Data publikacji:
2009-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.23.Hk
73.63.Kv
73.43.Qt
72.25.-b
Opis:
Effects of local vibrational modes on electron transport through a quantum dot attached to ferromagnetic electrodes are studied in the Kondo regime by the non-equilibrium Green function formalism based on the equation of motion method. Differential conductance is calculated for parallel and antiparallel configurations of the leads' magnetic moments, and well defined Kondo resonance peaks and their phonon satellites are found. The influence of a compensating magnetic field on the peak positions is also discussed.
Źródło:
Acta Physica Polonica A; 2009, 115, 1; 272-274
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin Polarized Transport through Quantum Dots: Coulomb Blockade and Kondo Effect
Autorzy:
Barnaś, J.
Świrkowicz, R.
Wilczyński, M.
Weymann, I.
Martinek, J.
Dugaev, V.
Powiązania:
https://bibliotekanauki.pl/articles/2036886.pdf
Data publikacji:
2003-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.25.-b
73.23.Hk
72.15.Qm
Opis:
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.
Źródło:
Acta Physica Polonica A; 2003, 104, 2; 165-177
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin Currents in Magnetic Nanostructures
Autorzy:
Dugaev, V.
Bruno, P.
Barnaś, J.
Powiązania:
https://bibliotekanauki.pl/articles/1811907.pdf
Data publikacji:
2008-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.25.-b
73.23.Ra
75.75.+a
Opis:
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.
Źródło:
Acta Physica Polonica A; 2008, 114, 5; 975-982
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Poor Mans Scaling and Green Function Analysis of the Kondo Anomaly in Single-Level Quantum Dots
Autorzy:
Wawrzyniak, M.
Świrkowicz, R.
Wilczyński, M.
Barnaś, J.
Powiązania:
https://bibliotekanauki.pl/articles/1813883.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.Hr
72.15.Qm
72.25.-b
73.23.Hk
Opis:
Kondo effect in a single-level quantum dot attached to magnetic leads is studied theoretically by the "poor man's scaling" and non-equilibrium Green function methods. From the scaling equations we derive the Kondo temperature as a function of the model parameters - in particular as a function of the angle between magnetic moments. Transport characteristics, i.e. differential conductance and tunnel magnetoresistance associated with magnetization rotation, were calculated within the non-equilibrium Green function formalism based on the equation of motion method.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 553-556
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nonequilibrium Kondo Effect in a Single-Channel Quantum Dot Asymmetrically Coupled to Two Ferromagnetic Reservoirs
Autorzy:
Świrkowicz, R.
Wilczyński, M.
Barnaś, J.
Powiązania:
https://bibliotekanauki.pl/articles/2037118.pdf
Data publikacji:
2004
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.Hr
72.15.Qm
72.25.-b
73.23.Hk
Opis:
Nonequilibrium Kondo effect in a quantum dot asymmetrically coupled to two ferromagnetic metallic leads is analyzed theoretically. The nonequilibrium Green function technique is used to calculate density of states and electric current. The lesser and retarded (advanced) Green functions are calculated by the equation of motion method within a consistent approximation scheme. The case where one electrode is half-metallic is analyzed numerically in details.
Źródło:
Acta Physica Polonica A; 2004, 105, 1-2; 149-154
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-10 z 10

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