Autor: Weymann, I. - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Spin-Polarized Transport through Quantum Dots in the Cotunneling Regime
Autorzy:: Weymann, I.
Powiązania:: https://bibliotekanauki.pl/articles/1813873.pdf
Data publikacji:: 2008-01
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 72.25.Mk
73.63.Kv
85.75.-d
73.23.Hk
Opis:: The spin-polarized transport through two-level quantum dots weakly coupled to ferromagnetic leads is considered theoretically in the Coulomb blockade regime. It is assumed that the dot is doubly occupied, so that the current flows due to cotunneling through singlet and triplet states of the dot. It is shown that, by sweeping the bias voltage, one can induce a singlet-triplet transition, which depends on the magnetic configuration of the system and leads to nontrivial bias dependence of both the differential conductance and tunnel magnetoresistance.
Źródło:: Acta Physica Polonica A; 2008, 113, 1; 529-532
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

Artykuł

Skocz do pozycji: 2.

Tytuł:: Current Suppression in Transport Through Triple Quantum Dots Coupled to Ferromagnetic Leads
Autorzy:: Wrześniewski, K.
Weymann, I.
Powiązania:: https://bibliotekanauki.pl/articles/1386617.pdf
Data publikacji:: 2015-02
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 73.23.-b
73.21.La
85.75.-d
Opis:: We consider transport through triple quantum dot system in a triangular geometry weakly coupled to external ferromagnetic leads. The real-time diagrammatic technique in the lowest order perturbation theory is used to calculate the current and Fano factor in the parallel and antiparallel magnetic configuration of the system as well as the resulting tunnel magnetoresistance (TMR). We focus on the transport regime where the current is suppressed and show that it can lead to negative differential conductance and large super-Poissonian shot noise, which are present in both magnetic configurations. Furthermore, we show that for voltages where the system is trapped in a one-particle dark state the TMR becomes suppressed, while for two-particle blockade, the TMR is much enhanced.
Źródło:: Acta Physica Polonica A; 2015, 127, 2; 460-462
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

Artykuł

Skocz do pozycji: 3.

Tytuł:: Spin-Dependent Transport through a Single-Wall Carbon Nanotube Quantum Dot with an S=1 Molecule
Autorzy:: Płomińska, A.
Weymann, I.
Powiązania:: https://bibliotekanauki.pl/articles/1386697.pdf
Data publikacji:: 2015-02
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 72.25.-b
75.50.Xx
85.75.-d
Opis:: Transport properties of an S=1 molecule attached to a single-wall carbon nanotube quantum dot, which is coupled to two external ferromagnetic leads, are analyzed in the sequential tunneling regime. The magnetizations of the leads are assumed to form either a parallel or an antiparallel magnetic configuration. The calculations are performed by using the real-time diagrammatic technique in the lowest order perturbation theory with respect to the tunnel coupling. It is shown that the presence of the molecule strongly affects the bias voltage dependence of the current and differential conductance in both magnetic configurations, as well as the resulting tunnel magnetoresistance. Negative (greatly enhanced) tunnel magnetoresistance is found in the case of antiferromagnetic (ferromagnetic) coupling between the nanotube and molecule.
Źródło:: Acta Physica Polonica A; 2015, 127, 2; 475-477
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

Artykuł

Skocz do pozycji: 4.

Tytuł:: The Magnetic Field Effects on Spin Polarization of T-Shaped Double Quantum Dots Coupled to Ferromagnetic Leads
Autorzy:: Wójcik, K.
Weymann, I.
Powiązania:: https://bibliotekanauki.pl/articles/1384834.pdf
Data publikacji:: 2015-02
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 73.23.Hk
73.63.Kv
85.75.-d
Opis:: We analyze the spin-dependent conductance and spin polarization of a double quantum dot in a T-shape configuration coupled to ferromagnetic leads in the presence of external magnetic field. The calculations are performed with the aid of the numerical renormalization group method. We show that in the antiparallel configuration, finite magnetic field can give rise to the full spin polarization of the current, which can be controlled by tuning the dots' levels. On the other hand, for parallel configuration enhanced spin polarization can be generated by an exchange field due to the presence of ferromagnetic leads and can be also tuned by changing level position or external magnetic field. The magnetic field can be thus used to improve the spin-resolved properties of the system.
Źródło:: Acta Physica Polonica A; 2015, 127, 2; 222-224
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

Artykuł

Skocz do pozycji: 5.

Tytuł:: Transport through Single-Wall Carbon Nanotubes Weakly Coupled to External Leads
Autorzy:: Weymann, I.
Krompiewski, S.
Barnaś, J.
Powiązania:: https://bibliotekanauki.pl/articles/1810542.pdf
Data publikacji:: 2009-01
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 72.25.Mk
73.63.Kv
85.75.-d
73.23.Hk
Opis:: We consider transport properties of single-wall metallic carbon nanotubes weakly coupled to external leads. In particular, we analyze the conductance and shot noise of nanotubes coupled to nonmagnetic leads and show that the shot noise may become super-Poissonian depending on the ground state of the nanotube. In addition, we also show that when the nanotube is coupled to one ferromagnetic and one nonmagnetic lead, it can operate as a gate-controlled spin diode.
Źródło:: Acta Physica Polonica A; 2009, 115, 1; 296-298
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

Artykuł

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