Full-text resources of PSJD and other databases are now available in the new Library of Science.
Visit https://bibliotekanauki.pl

Refine search results

Journals help

  1. 55 Acta Physica Polonica A

  2. 2 Open Physics

Years help

  1. 1 2018

  2. 2 2017

  3. 2 2016

  4. 8 2015

  5. 2 2014

More...
Authors help

  1. 6 Bułka B.

  2. 6 Weymann I.

  3. 5 Barnaś J.

  4. 4 Domański T.

  5. 4 Donabidowicz A.

More...
Preferences help
Polish version English version Language
enabled [disable] Abstract
Number of results

Results found: 57

Number of results on page
first rewind previous Page / 3 next fast forward last

Search results

Search:
in the keywords:  73.23.-b
help Sort By:

help Limit search:
first rewind previous Page / 3 next fast forward last
1
Content available remote

Many-Channel Landauer-Like Conductance Formula in a Uniform Magnetic Field

100%
Benamira F., Abdellaoui A.
Acta Physica Polonica A
|
2012
|
vol. 122
|
issue 4
721-724
EN
Linear-response theory is combined with the Landauer viewpoint to describe quantitatively transport in a four-lead mesoscopic structure within the presence of a uniform magnetic field. A new multichannel magnetoconductance formula is derived in the case where the magnetic field is perpendicular to the current-flow. The invariance under magnetic reversal test is confirmed.
2
Content available remote

Two-Dimensional Analytical Threshold Voltage Modelling of Pseudomorphic Si_{0.8}Ge_{0.2} p-Channel MOSFETs

100%
Ansaripour G.
Acta Physica Polonica A
|
2011
|
vol. 120
|
issue 6
1043-1046
EN
In this work we present an analytical model of the threshold voltage of SiGe p-channel metal oxide semiconductor field effect transistor based on the solution of the two-dimensional Poisson's equation and the ground state wave function of Fang and Howard, and taking into account the space charge in the channel and its effect on the surface potential. It is seen that the experimental data are well fitted within the experimental error that shows the appropriateness of the implemented model. Also comparing the calculated results to that of the calculated from the available recent reported models indicates a reasonable improvement to them.
3
Publication available in full text mode
Content available

Quantum-Interference Semiconductor Devices Revisited

63%
Figielski T.
Acta Physica Polonica A
|
2001
|
vol. 99
|
issue 6
699-708
EN
First, a simple semiclassical approach has been applied to the problem of a quantum phase acquired by an electron carrying both the charge and spin, which travels in an electromagnetic field. Basic hypothetical devices whose operation relies on the quantum interference, including spin-related interference, are discussed in the following. Finally, experimental results demonstrating two-beam interference in a planar quantum dot are presented.
4
Publication available in full text mode
Content available

Tunneling of Interacting Fermions in 1D Systems

63%
Gendiar A., Moško M., Vagner P., Németh R.
Acta Physica Polonica A
|
2005
|
vol. 108
|
issue 4
661-667
EN
Using the self-consistent Hartree-Fock approximation for spinless electrons at zero temperature, we study tunneling of the interacting electron gas through a single δ barrier in a finite one-dimensional wire connected to contacts. Our results exhibit features known from correlated many-body models. In particular, the conductance decays with the wire length as ∝ L^{-2α}, where the powerα is universal. We also show that a similar result for a wire conductance can be extracted from the persistent current (I) through theδ barrier in a one-dimensional ring, where it is known that I∝ L^{-1-α}.
5
Content available remote

Influence of Magnetic Field on Dark States in Transport through Triple Quantum Dots

63%
Wrześniewski K., Weymann I.
Acta Physica Polonica A
|
2017
|
vol. 132
|
issue 1
108-111
EN
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.
6
Content available remote

Current Shot Noise and Bunching of Electrons in Multilevel Quantum Dots

63%
Michałek G., Bułka B.
Acta Physica Polonica A
|
2008
|
vol. 113
|
issue 1
27-30
EN
Currents and their fluctuations in multilevel quantum dots are studied theoretically in the limit of sequential tunneling. The spin degrees of freedom, many-body electronic states (singlet and triplet) as well as relaxation processes between the levels of the quantum dots are considered. In general, due to the rapid relaxation processes the shot noise is sub-Poissonian, however for a large polarization of the outgoing currents from the singlet and triplet states one gets the super-Poissonian type of the shot noise due to the bunching of tunneling events.
7
Publication available in full text mode
Content available

Terahertz Generation and Detection by Plasma Waves in Nanometer Gate High Electron Mobility Transistors

63%
Knap W., Łusakowski J., Teppe F., Dyakonova N., Meziani Y.
Acta Physica Polonica A
|
2005
|
vol. 107
|
issue 1
82-91
EN
The high electron mobility transistors can act as a resonator cavity for the plasma waves that can reach THz frequencies for a nanometer size devices. As was predicted by Dyakonov and Shur in 1993, the steady state of the current flow in a gated 2D electron gas can become unstable leading to the emission of an electromagnetic radiation at the plasma wave frequencies. The theory predicted also that the plasma waves can be used for resonant detection of THz electromagnetic radiation. In the present paper we review our recent experiments on THz emission and detection performed on high electron mobility transistors based on different semiconductor structures: InGaAs/GaAlAs, GaAs/GaAlAs, and Si.
8
Publication available in full text mode
Content available

Hartree-Fock Simulation of Persistent Current in Rings with Single Scatterer

63%
Németh R., Moško M.
Acta Physica Polonica A
|
2005
|
vol. 108
|
issue 5
795-801
EN
Using the self-consistent Hartree-Fock approximation for spinless electrons at zero temperature, we calculate the persistent current of the interacting electron gas in a one-dimensional ring containing a singleδ barrier. Our results agree with correlated models like the Luttinger liquid model and lattice model with nearest-neighbor interaction. The persistent current is a sine-like function of magnetic flux. It decays with the ring length (L) faster than L^{-1} and eventually like L^{-α-1}, where α>0 is universal.
9
Publication available in full text mode
Content available

Mutual Inductance and Selfinductance in Mesoscopic Systems

63%
Zipper E., Dajka J., Szopa M.
Acta Physica Polonica A
|
2002
|
vol. 102
|
issue 3
419-428
EN
The role played by the magnetostatic interaction in mesoscopic multichannel systems is discussed. We show that the interaction of currents from different channels, when taken in the selfconsistent mean field approximation, leads to selfinductance terms in the Hamiltonian producing an internal magnetic flux. Such multichannel systems can exhibit spontaneous flux or flux expulsion. The dependence of these phenomena on the parameters of the system is discussed.
10
Content available remote

Magnetoresistance in Graphene-Based Ferromagnetic/ Rashba Barrier/Ferromagnetic Heterojunction

51%
Mohammadpour H., Hasanirokh K.
Acta Physica Polonica A
|
2016
|
vol. 129
|
issue 1
75-78
EN
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.
11
Content available remote

Andreev Transport in Double Quantum Dot Cooper Pair Splitters in the Presence of External Magnetic Field

51%
Trocha P., Weymann I.
Acta Physica Polonica A
|
2015
|
vol. 127
|
issue 2
502-504
EN
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.
12
Content available remote

Electron Transport in Magnetic Quantum Point Contacts

51%
Pietsch T., Egle S., Espy C., Strigl F., Scheer E.
Acta Physica Polonica A
|
2012
|
vol. 121
|
issue 2
401-409
EN
In recent years, the fabrication of novel building blocks for quantum computation- and spintronics devices gained significant attention. The ultimate goal in terms of miniaturization is the creation of single-atom functional elements. Practically, quantum point contacts are frequently used as model systems to study the fundamental electronic transport properties of such mesoscopic systems. A quantum point contact is characterised by a narrow constriction coupling two larger electron reservoirs. In the absence of a magnetic field, the conductance of these quantum point contacts is quantised in multiples of 2 e^2/h, the so-called conductance quantum (G_0). However, in the presence of magnetic fields the increased spin-degeneracy often gives rise to a deviation from the idealized behaviour and therefore leads to a change in the characteristic conductance of the quantum point contact. Herein, we illustrate the complex magnetotransport characteristics in quantum point contacts and magnetic heterojunctions. The theoretical framework and experimental concepts are discussed briefly together with the experimental results as well as potential applications.
13
Content available remote

Andreev Conductance through a Quantum Dot Strongly Coupled to Ferromagnetic and Superconducting Leads

51%
Wójcik K. P., Weymann I.
Acta Physica Polonica A
|
2017
|
vol. 132
|
issue 1
143-145
EN
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.
14
Content available remote

Entanglement Detection with Non-Ideal Ferromagnetic Detectors

51%
Rożek P., Busz P., Kłobus W., Tomaszewski D., Grudka A., Baumgartner A., Schönenberger C., Martinek J.
Acta Physica Polonica A
|
2015
|
vol. 127
|
issue 2
493-495
EN
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.
15
Content available remote

Kondo-Fano Effect in Double Quantum Dot Side Attached to a Pair of Wires

51%
Krychowski D., Lipiński S.
Acta Physica Polonica A
|
2015
|
vol. 127
|
issue 2
487-489
EN
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.
16
Content available remote

Andreev Transport through a Magnetic Molecule Weakly Coupled to Ferromagnetic Leads

51%
Pawlicki F., Weymann I.
Acta Physica Polonica A
|
2018
|
vol. 133
|
issue 3
594-596
EN
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.
17
Content available remote

Spin Thermoelectric Effects in a Strongly Correlated Double Quantum Dot System

51%
Karwacki Ł.
Acta Physica Polonica A
|
2015
|
vol. 127
|
issue 2
478-480
EN
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.
18
Content available remote

Statistical Investigation of Current-Voltage Characterization in Single Molecule-Metal Junctions

51%
Kirchner T., Briechle B., Scheer E., Wolf J., Huhn T., Erbe A.
Acta Physica Polonica A
|
2012
|
vol. 121
|
issue 2
410-415
EN
We show statistical measurements of single molecule-metal contacts using the mechanically controllable break junction technique. The measurements are carried out in a solvent, in order to allow in situ binding of the molecules to the metallic contacts during the measurements. Statistics is gathered by opening and closing the junctions repeatedly and recording current-voltage characteristics at various stages of the opening and closing curves. By modeling the data with a single level model we can extract parameters such as the position of the molecular energy level, which carries the current, and the coupling between the metal and the molecule. In first experiments we use this method to characterize different anchoring groups, which mediate the mechanical and electrical coupling between the metallic electrodes and the molecules. We use tolane molecules, which are structurally simple, as model systems for this purpose.
19
Publication available in full text mode
Content available

Electron Transport through Double Quantum Dot System with Inter-Dot Coulomb Interaction

51%
Sztenkiel D., Świrkowicz R.
Acta Physica Polonica A
|
2007
|
vol. 111
|
issue 3
361-372
EN
A theoretical approach to a problem of electron transport through double quantum dot systems based on non-equilibrium Green function formalism using equation of motion method is presented. I-V characteristics and differential conductance are calculated and discussed in detail in the intermediate regime with tunneling rate between the quantum dots comparable to coupling constants with external electrodes. Effects of inter-dot Coulomb correlations are studied for various values of interaction parameter U. It is shown that the interaction influences transport properties in a pronounced way and apart from the simple Coulomb blockade additional effects can be obtained. When energy levels of two quantum dots are not aligned, the asymmetry in conductance characteristics is closely related to a voltage dependence of population numbers in both quantum dots. For a one bias polarization electrons are well localized in quantum dots in a low voltage region, whereas for the opposite one they are partly delocalized.
20
Content available remote

Entanglement Detection by Current Measurements in Double Quantum Dot System

51%
Busz P., Rożek P., Tomaszewski D., Martinek J.
Acta Physica Polonica A
|
2015
|
vol. 127
|
issue 2
490-492
EN
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.
first rewind previous Page / 3 next fast forward last
JavaScript is turned off in your web browser. Turn it on to take full advantage of this site, then refresh the page.