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


Tytuł:
Andreev Transport through a Magnetic Molecule Weakly Coupled to Ferromagnetic Leads
Autorzy:
Pawlicki, F.
Weymann, I.
Powiązania:
https://bibliotekanauki.pl/articles/1030385.pdf
Data publikacji:
2018-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.23.-b
74.45.+c
75.50.Xx
Opis:
The Andreev transport through a single molecular magnet coupled to two external ferromagnetic leads and one superconducting electrode is studied theoretically by means of the real-time diagrammatic technique. The calculations are performed by including the sequential tunneling processes between the molecule and ferromagnetic leads, while the coupling to superconductor can be arbitrary. We analyze the dependence of the Andreev current and tunnel magnetoresistance on various intrinsic parameters of the molecule. The superconducting proximity effect results in the formation of molecular Andreev bound states. We show that the transport behavior depends greatly on the type of internal exchange interaction of the molecule, which can lead to corresponding sign changes of the tunnel magnetoresistance of the device.
Źródło:
Acta Physica Polonica A; 2018, 133, 3; 594-596
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Andreev Conductance through a Quantum Dot Strongly Coupled to Ferromagnetic and Superconducting Leads
Autorzy:
Wójcik, K.P.
Weymann, I.
Powiązania:
https://bibliotekanauki.pl/articles/1032390.pdf
Data publikacji:
2017-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.23.-b
72.15.Qm
74.45.+c
72.25.-b
Opis:
We analyze the Andreev conductance through a quantum dot strongly coupled to one ferromagnetic and one superconducting lead. The transmission due to the Andreev reflection is obtained from the numerical renormalization group method. We show that at low temperatures, depending on the dot level position, the Andreev conductance exhibits a peak at zero bias due to the Kondo effect, which can be split by the exchange field due to spin-dependent coupling to ferromagnetic lead.
Źródło:
Acta Physica Polonica A; 2017, 132, 1; 143-145
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Magnetic Field on Dark States in Transport through Triple Quantum Dots
Autorzy:
Wrześniewski, K.
Weymann, I.
Powiązania:
https://bibliotekanauki.pl/articles/1032454.pdf
Data publikacji:
2017-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.23.-b
73.21.La
Opis:
We theoretically study the electronic transport through a triple quantum dot system in triangular geometry weakly coupled to external metallic leads. By means of the real-time diagrammatic technique, the current and Fano factor are calculated in the lowest order of perturbation theory. The device parameters are tuned to such transport regime, in which coherent population trapping of electrons in quantum dots due to the formation of dark states occurs. The presence of such states greatly influences transport properties leading to a strong current blockade and enhanced, super-Poissonian shot noise. We consider both one- and two-electron dark states and examine the influence of magnetic field on coherent trapping in aforementioned states. When the system is in one-electron dark state, we observe a small shift of the blockade's region, whereas in the case of two-electron dark state, we show that strong magnetic field can lift the current blockade completely.
Źródło:
Acta Physica Polonica A; 2017, 132, 1; 108-111
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetoresistance in Graphene-Based Ferromagnetic/ Rashba Barrier/Ferromagnetic Heterojunction
Autorzy:
Mohammadpour, H.
Hasanirokh, K.
Powiązania:
https://bibliotekanauki.pl/articles/1191228.pdf
Data publikacji:
2016-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.80.Vp
73.23.-b
73.22.Pr
Opis:
The quantum tunnelling of spin-polarized electrons through a Rashba barrier on a single layer graphene is studied by the scattering matrix method. It is shown that the magnetoresistance, defined as the difference between conductance at the presence and absence of the Rashba spin-orbit interaction, oscillates with the intensity of interaction. These oscillations are also observed in the conductance versus the potential energy of the barrier.
Źródło:
Acta Physica Polonica A; 2016, 129, 1; 75-78
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the 2D quantum tunneling
Autorzy:
Mohammadpour, H.
Powiązania:
https://bibliotekanauki.pl/articles/1159450.pdf
Data publikacji:
2016-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.10.-d
72.10.Bg
72.80.Vp
72.90.+y
73.21.Fg
73.23.-b
73.23.Ad
73.40.Gk
Opis:
In this paper, we have solved a quantum tunneling problem for 2-dimensional systems, including electron gas and graphene. In spite of the one-dimensional scattering problems, in two dimensions, we observe phenomenon of tunneling at energies above the barrier. This effect is an analogue to the total internal reflection in optics. The scattering amplitudes inside the barrier region exhibit decaying behavior corresponding to optical evanescent-wave coupling, not only in energies below barrier height, but also above barrier. Velocity-selecting transmission, corresponding to angle-resolved beam filtering effect is one of the achievements of the paper. The famous Hartman effect which occurs normally at sub-barrier energies and has previously been studied for graphene is also addressed. The results manifest occurrence of the Hartman effect for over-barrier energies, as well.
Źródło:
Acta Physica Polonica A; 2016, 130, 3; 769-772
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Andreev Transport in Double Quantum Dot Cooper Pair Splitters in the Presence of External Magnetic Field
Autorzy:
Trocha, P.
Weymann, I.
Powiązania:
https://bibliotekanauki.pl/articles/1386830.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.23.-b
73.21.La
74.45.+c
Opis:
The effect of external magnetic field on the transport properties of double quantum dots coupled to normal and superconducting leads is studied by means of the real-time diagrammatic technique in the sequential tunneling regime. This device works as a gate-controlled Cooper pair splitter. We focus on the transport regime where the current is blocked due to the spin triplet blockade. It is shown that external magnetic field can modify the Andreev current and differential conductance. In particular, magnetic field can suppress the negative differential conductance associated with the triplet blockade.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 502-504
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
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
Tytuł:
Entanglement Detection by Current Measurements in Double Quantum Dot System
Autorzy:
Busz, P.
Rożek, P.
Tomaszewski, D.
Martinek, J.
Powiązania:
https://bibliotekanauki.pl/articles/1386781.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
03.67.Mn
03.67.Bg
73.23.-b
Opis:
The development of quantum computing in quantum dots systems requires highly efficient and continuous solid-state source of spatially separated spin-entangled electrons. One of the approaches is a use of double quantum dot system connected to superconducting lead, where Cooper pairs provide a source of naturally entangled electrons. Apart from the source, an useful tool for detection of quantum entanglement is needed. We present entanglement detection by the ferromagnetic electrodes using entanglement witness operator method and direct measurement of spin polarized current in the system. We investigate requirements that have to be fulfilled by ferromagnetic detectors.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 490-492
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Entanglement Detection with Non-Ideal Ferromagnetic Detectors
Autorzy:
Rożek, P.
Busz, P.
Kłobus, W.
Tomaszewski, D.
Grudka, A.
Baumgartner, A.
Schönenberger, C.
Martinek, J.
Powiązania:
https://bibliotekanauki.pl/articles/1386794.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
03.67.Mn
03.67.Bg
73.23.-b
Opis:
Entangled states are essential in basics quantum communication protocols and quantum cryptography. Ferromagnetic contacts can work as a spin detector, giving possibility of converting information about electron spin to the electric charge, and therefore, detection of entangled states with the electric current measurements is possible. Method of confirming entanglement with non-ideal detectors is presented, the impact of decoherence and noise on states and quality of entanglement is discussed. Entanglement witness (EW) operator method is compared with the CHSH inequalities approach. Required spin polarization for the EW is lower than for the CHSH inequalities. System with asymmetric spin polarizations of detectors was analyzed, including the CHSH inequalities and the EW method.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 493-495
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Kondo-Fano Effect in Double Quantum Dot Side Attached to a Pair of Wires
Autorzy:
Krychowski, D.
Lipiński, S.
Powiązania:
https://bibliotekanauki.pl/articles/1386758.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.10.Fk
73.21.-b
73.22.-f
73.23.-b
Opis:
Electron tunneling through a double quantum dot side coupled to a pair of leads is examined in finite-U slave boson mean field approach. Both the two-impurity Kondo regime at half filling and one-and three-electron Kondo effects are analyzed. Special attention is paid to the case when one of the dots is coupled to ferromagnetic lead and another to nonmagnetic. Depending on the gate voltage, the same or opposite sign of polarizations of conductance of the leads is observed.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 487-489
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Signatures of Majorana States in Electron Transport through a Quantum Dot Coupled to a Topological Wire
Autorzy:
Stefański, P.
Powiązania:
https://bibliotekanauki.pl/articles/1384812.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.63.-b
73.23.Hk
73.21.La
74.78.Na
Opis:
We consider theoretically a system composed of a quantum dot coupled to a topological superconducting wire. The dot, being in Coulomb blockade (CB) regime is additionally coupled to the normal leads. The topological wire hosts Majorana states, which, as we show, characteristically modifies conductance through the dot. An unpaired Majorana state in the wire causes a unique temperature dependence of zero bias conductance vs. gate voltage. It decreases in-between CB peaks and on the sides of the peaks from the plateau at ~ e²/2h when temperature increases. At the same time conductance increases at the CB peak positions. It is accompanied by zero bias anomaly in differential conductance. For finite overlap of Majorana states in the wire the zero bias anomaly disappears. Instead, two characteristic Fano resonances of opposite symmetry appear, positioned mirror-symmetrically with respect to zero bias.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 198-200
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:
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:
Spin Thermoelectric Effects in a Strongly Correlated Double Quantum Dot System
Autorzy:
Karwacki, Ł.
Powiązania:
https://bibliotekanauki.pl/articles/1386717.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.23.-b
73.63.Kv
72.15.Qm
85.35.Ds
Opis:
Spin thermoelectric effects through a strongly correlated double quantum dot system embedded in a Aharonov-Bohm ring coupled to two leads with Rashba spin-orbit coupling have been investigated theoretically by means of the finite-U slave-boson technique. This method provides a reliable description of electron transport through quantum dot systems in the low temperature regime T ≪ $T_{K}$, where $T_{K}$ is the so-called Kondo temperature. Particular emphasis is put on the possibility of the so-called spin Seebeck effect in such a system as a more sensitive probe of the Kondo state.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 478-480
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fano-Kondo Effect of Magnetic Impurity with Side-Coupled Graphene Flake
Autorzy:
Krychowski, D.
Kopiński, J.
Lipiński, S.
Powiązania:
https://bibliotekanauki.pl/articles/1201853.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.22.Pr
72.80.Vp
73.23.-b
72.15.Qm
85.75.-d
Opis:
We examine transport through a spin-1/2 Kondo impurity, patterned between atomic scale electrodes in the presence of side-coupled nanographene flake. Impurity is attached to the edge of the flake, what allows to test the edge states. The Kotliar Ruckenstein slave boson approach is adopted to describe the strongly correlated impurity. We show that transport measurement of Fano-Kondo effect can serve as a spectroscopic probe of spin resolved graphene flake energy levels. The edge moments can be completely suppressed by gate voltage.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 202-203
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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