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Wyszukujesz frazę "85.75.-d" wg kryterium: Temat


Tytuł:
Electron Mediated Mn-Mn Interaction in Quantum Dots
Autorzy:
Bak, Z.
Powiązania:
https://bibliotekanauki.pl/articles/1428517.pdf
Data publikacji:
2012-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.75.-c
75.85.+t
85.75.-d
Opis:
We present a theoretical study of magnetic interaction in quantum dots with magnetic $Mn^{2+}$ in dot impurities. We show that gate voltage applied to the quantum dot shifts the centers of electron clouds. Exact formulae for the perturbed spin density allow us to derive expression for the change of the strength of the sp-d coupling. Estimations show that sp-d exchange integral is very sensitive to the gate voltage variations. Exact formulae for the change of the effective exchange integrals are derived. As the spin coded qubits are elements of the RAM memory, a part of the energy stored in magnetic coupling will be dissipated when information is written or erased. We estimate this energy and find it sufficiently large to destroy quantum coherence during quantum computing. Finally, we discuss the interdot spin coupling and show the effect of gate voltage operations on the spin intra- and interdot Ruderman-Kittel-Kasuya-Yosida coupling.
Źródło:
Acta Physica Polonica A; 2012, 121, 5-6; 1219-1221
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Field Sensor Based on Magnetic Tunnel Junction with Voltage-Tunable Magnetic Anisotropy
Autorzy:
Skowroński, W.
Wiśniowski, P.
Wrona, J.
Żywczak, A.
Stobiecki, T.
Powiązania:
https://bibliotekanauki.pl/articles/1386807.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
85.75.-d
85.75.Ss
85.35.-p
Opis:
We present a submicron magnetic field sensor with voltage-tunable magnetic field sensitivity. The device, based on magnetic tunnel junction, exhibits high tunnelling magnetoresistance ratio of up to 90%. Perpendicular magnetic anisotropy of thin ferromagnetic sensing layer in combination with an in-plane magnetized reference layer is used to obtain linear change in the sensor resistance in response to the in-plane magnetic field. The perpendicular anisotropy is further controlled by the bias voltage and, thus, the sensitivity of the sensor is changed. In addition, we evaluate the sensor selectivity for the magnetic field direction and present an influence of the temperature on the anisotropy.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 496-498
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Carrier Spin Dephasing during Spin-Preserving Tunneling in Coupled Quantum Dots
Autorzy:
Krzykowski, M.
Gawełczyk, M.
Machnikowski, P.
Powiązania:
https://bibliotekanauki.pl/articles/1185791.pdf
Data publikacji:
2016-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
85.75.-d
03.65.Yz
Opis:
In this contribution we study carrier tunneling in a system consisting of a pair of coupled quantum dots. We predict the presence of a spin dephasing channel in such a system, which is associated with a "welcher-weg" type of decoherence process occurring during carrier tunneling. In our model such a process is caused by a mismatch of g-factor values in two quantum dots in the presence of external magnetic field. This leads to a mismatch in spin Zeeman splitting between the dots and, in consequence, to the distinguishability of phonons emitted during the tunneling of carriers with opposite spins. Thus we demonstrate a process of spin dephasing without any direct spin-environment coupling present in the model.
Źródło:
Acta Physica Polonica A; 2016, 130, 5; 1165-1168
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Accuracy of Effective Mass Equation for a Single and Double Cylindrical Quantum Dot
Autorzy:
Mielnik-Pyszczorski, A.
Gawarecki, K.
Machnikowski, P.
Powiązania:
https://bibliotekanauki.pl/articles/1033130.pdf
Data publikacji:
2017-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
85.75.-d
03.65.Yz
Opis:
In this contribution we study the accuracy of various forms of electron effective mass equation in reproducing spectral and spin-related features of quantum dot systems. We compare the results of the standard 8 band k·p model to those obtained from effective mass equations obtained by perturbative elimination procedures in various approximtions for a cylindrical quantum dot or a system of two such dots. We calculate the splitting of electronic shells, the electron g-factor and spin-orbit induced spin mixing and show that for a cylindrical dot the g-factor is reproduced very exactly, while for the two other quantities the effective mass equation is much less accurate.
Źródło:
Acta Physica Polonica A; 2017, 132, 2; 376-379
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bychkov-Rashba Effect and g-Factor Tuning in Modulation Doped SiGe Quantum Wells
Autorzy:
Malissa, H.
Jantsch, W.
Mühlberger, M.
Schäffler, F.
Wilamowski, Z.
Draxler, M.
Bauer, P.
Powiązania:
https://bibliotekanauki.pl/articles/2038126.pdf
Data publikacji:
2004-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.21.Fg
85.75.-d
Opis:
We investigate the spin resonance of electrons in one-sided modulation doped Si$\text{}_{1-x}$Ge$\text{}_{x}$ (x=0-10%)) quantum wells defined by Si$\text{}_{0.75}$Ge$\text{}_{0.25}$ barriers. In such structures, the Bychkov-Rashba effect induces an effective magnetic field in the quantum well layer which causes anisotropy of both the g-factor and the spin coherence time. Evaluation of the Rashba coefficient as a function of x yields a monotonic increase. For x=5% the shift in the resonance field exceeds the ESR linewidth already, demonstrating the possibility to use this effect for g-factor tuning to select individual spins in an ensemble.
Źródło:
Acta Physica Polonica A; 2004, 105, 6; 585-590
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic and structural characterization of NiXSb (X = Mn, Cr) Heusler ribbon
Autorzy:
Ryba, T.
Vargova, Z.
Ilkovic, S.
Reiffers, M.
Kravcak, J.
Gyepes, R.
Varga, R.
Powiązania:
https://bibliotekanauki.pl/articles/1050967.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.47.Np
75.30.Gw
85.75.-d
Opis:
Half-Heusler alloys with composition NiMnSb and NiCrSb have been prepared by rapid-quenching method. NiMnSb half-Heusler alloy is characterized by single phase C1_{b} with polycrystalline structure while crystalline structure of NiCrSb shows multiphase system. Magnetic measurements indicated high anisotropy and easy magnetization direction in the parallel direction with respect to ribbon axis for NiMnSb alloy while paramagnetic behavior appears for NiCrSb alloy down to 50 K.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 857-859
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Inverse Edelstein Effect: an Heuristic Derivation
Autorzy:
Raimondi, R.
Shen, Ka
Vignale, G.
Powiązania:
https://bibliotekanauki.pl/articles/1386587.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.25.Dc
75.70.Tj
85.75.-d
Opis:
We provide a heuristic derivation of the "Inverse Edelstein Effect" (IEE), in which a non-equilibrium spin accumulation in the plane of a two-dimensional (interfacial) electron gas drives an electric current perpendicular to its own direction. The drift-diffusion equations that govern the effect are derived and applied to the interpretation of recent experiments. A brief analysis based on the Kubo formula shows that the result is valid also outside the diffusive regime, i.e. when spin and momentum relaxation become comparable.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 454-456
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin Hall and Edelstein Effects in Metallic Films
Autorzy:
Borge, J.
Gorini, C.
Vignale, G.
Raimondi, R.
Powiązania:
https://bibliotekanauki.pl/articles/1386604.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.25.Mk
75.70.Tj
85.75.-d
Opis:
In an insulator-metal-insulator junction, inversion-symmetry breaking at the interfaces between the 3D metallic film and the top and bottom insulating layers may give rise to a sizeable (Rashba-like) spin-orbit interaction. In this paper we study the spin Hall and Edelstein effects produced by such an interface interaction through a quasiclassical approach. We find that the spin Hall conductivity has a finite value even if spin-orbit interaction with impurities in the bulk of the metallic film is neglected and disorder is properly taken into account. This is in sharp contrast with the case of a strictly 2D metallic layer, in which case impurity scattering is known to completely suppress Rashba-like contributions to the spin Hall conductivity. The non-vanishing of the latter has a profound influence on the Edelstein effect, which we show to consist of two terms, the first with the standard form valid in an exactly 2D system, and a second arising from the presence of the third dimension.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 457-459
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
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
Tytuł:
From Magnetic Nanoparticles to Magnetoresistive Biosensors
Autorzy:
Ennen, I.
Albon, C.
Weddemann, A.
Auge, A.
Hedwig, P.
Wittbracht, F.
Regtmeier, A.
Akemeier, D.
Dreyer, A.
Peter, M.
Jutzi, P.
Mattay, J.
Mitzel, N.
Mill, N.
Hütten, A.
Powiązania:
https://bibliotekanauki.pl/articles/1490090.pdf
Data publikacji:
2012-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
85.70.-w
85.75.-d
75.75.Fk
64.75.Yz
87.85.fk
Opis:
This paper highlights recent advances in synthesis and magnetotransport properties of magnetic Co nanoparticles. It is shown that magnetic Co nanoparticles self-assembled in nanoparticular monolayers revealing giant magnetoresistance similar to granular systems but with additional features resulting from dipolar interactions between small domains of nanoparticles. A spin-valve with one magnetic Co nanoparticular electrode is employed as a model to demonstrate that individual magnetic moments of Co nanoparticles can be coupled to a magnetic Co layer which in turn offers tailoring of the resulting giant magnetoresistance characteristics. In addition, it is demonstrated that combining a magnetic on-off ratchet with magnetic tunneling junctions integrated in the ratchet introduces a new biosensor concept enabling: (1) simultaneous transporting and separating biomolecules, (2) dynamical biomolecule detection when passing magnetic tunneling junctions in a 1D arrangement. It is projected that this biosensor concept could be applied for viruses as well as for bacteria.
Źródło:
Acta Physica Polonica A; 2012, 121, 2; 420-425
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dyakonov--Perel Spin Relaxation Suppressed by an Applied Magnetic Field
Autorzy:
Wilamowski, Z.
Jantsch, W.
Powiązania:
https://bibliotekanauki.pl/articles/2036865.pdf
Data publikacji:
2003-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.25.Rb
73.21.Fg
85.75.-d
Opis:
We observe a strong anisotropy of spin relaxation and a decrease in the spin relaxation rate with increasing electron mobility in contrast to predictions of the classical D'yakonov-Perel spin relaxation model. We show that for high electron mobility the cyclotron motion causes an additional modulation of spin-orbit coupling, leading to an effective suppression of the spin relaxation rate.
Źródło:
Acta Physica Polonica A; 2003, 103, 6; 671-674
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin-Dependent Tunneling in a Magnetic Field for Junctions Involving Normal and Superconducting CDW Metals
Autorzy:
Ekino, T.
Gabovich, A. M.
Suan Li, Mai
Pękała, M.
Szymczak, H.
Voitenko, A. I.
Powiązania:
https://bibliotekanauki.pl/articles/2046730.pdf
Data publikacji:
2006-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.45.Lr
74.50.+r
85.75.-d
Opis:
The voltage, V, dependences of the differential tunnel conductance G(V) were calculated for two kinds of junctions involving normal and superconducting charge-density-wave metals (CDWMs) in the external magnetic field H. The first is a non-symmetrical junction with a CDWM electrode being biased with respect to a ferromagnet. Calculations show that the paramagnetic splitting occurs between spin-up and spin-down components of G(V), similar to what is observed when a superconducting electrode is used instead of the CDWM one. The second setup is symmetric (CDWM-I-CDWM), where I denotes an insulator. If at least one of the CDWM electrodes is normal and H≠0, G(V) will also be spin-split.
Źródło:
Acta Physica Polonica A; 2006, 109, 4-5; 477-484
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Current-Induced Magnetic Dynamics in Asymmetric Ferromagnetic Single-Electron Devices
Autorzy:
Kowalik, M.
Powiązania:
https://bibliotekanauki.pl/articles/1810537.pdf
Data publikacji:
2009-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.25.-b
73.23.Hk
85.75.-d
Opis:
The theoretical calculations of possible dynamics for a localized magnetic moment of the central electrode in ferromagnetic single-electron devices are presented. The spin-transfer torque from spin current absorbed by the central electrode is calculated. Thereafter, an in-plane component of spin torque is regarded during the integration of the Landau-Lifshitz-Gilbert equation and the time evolution of the localized magnetic moment of the central electrode is obtained. The necessary conditions for switching of the magnetic moment are discussed.
Źródło:
Acta Physica Polonica A; 2009, 115, 1; 290-292
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
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
Tytuł:
Spin-Dependent Transient Effects in Electron Transport in the Quantum Dot System
Autorzy:
Parafiniuk, P.
Taranko, R.
Powiązania:
https://bibliotekanauki.pl/articles/1791296.pdf
Data publikacji:
2009-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.25.-b
73.63.Kv
85.75.-d
Opis:
We study the effects of the Coulomb interaction U between the electrons of opposite spins localized in the quantum dot on the time-dependent electron transport through the quantum dot coupled with two non-magnetic leads. We calculate the transient spin-dependent current generated by a pulsed bias voltage applied across the quantum dot system via the equation of motion method for appropriate correlation functions. The influence of the Coulomb interaction on the quantum coherent oscillations and beats of the current, spin current and current polarization ratio is studied. Our results indicate that the coherent beats in both the total and spin currents observed in the case of vanishing Coulomb interaction are strongly suppressed by non-zero Coulomb interaction. We also show that in the case of the pulsed bias almost fully polarized current occurs in some time windows for non-vanishing Coulomb interaction contrary to almost pure charge or spin current at vanishing U.
Źródło:
Acta Physica Polonica A; 2009, 116, 5; 844-846
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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