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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Аксенов, Сергей Владимирович, Аксенов, Сергей Владимирович, Уланов Е. А.
Заглавие : Индуцирование спин-флип-процессами резонанса Фано при туннелировании электрона через спиновые структуры атомного масштаба
Место публикации : Журн. эксперим. и теор. физ. - 2013. - Т. 143, Вып. 5. - С. 984-990. - DOI 10.7868/S0044451013050248
Аннотация: Показано, что включение неупругих спин-зависящих процессов рассеяния электрона на потенциальных профилях одиночной магнитной примеси и спинового димера инициирует резонансные особенности, обусловленные эффектом Фано, в транспортных характеристиках таких спиновых структур атомного масштаба. Для реализации резонанса и антирезонанса Фано принципиальную роль играют спин-флип-процессы, приводящие к конфигурационному взаимодействию состояний системы. Установлено, что приложение внешнего магнитного поля и электрического поля затвора позволяет радикально изменять проводящие свойства спиновых структур через резонансный механизм Фано
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Aksenov S. V., Ulanov E. A.
Заглавие : Spin-flip induction of Fano resonance upon electron tunneling through atomic-scale spin structures
Место публикации : J. Experim. Theor. Phys.: Springer, 2013. - Vol. 116, Is. 5. - P.854-859. - DOI 10.1134/S1063776113050130
Аннотация: The inclusion of inelastic spin-dependent electron scatterings by the potential profiles of a single magnetic impurity and a spin dimer is shown to induce resonance features due to the Fano effect in the transport characteristics of such atomic-scale spin structures. The spin-flip processes leading to a configuration interaction of the system’s states play a fundamental role for the realization of Fano resonance and antiresonance. It has been established that applying an external magnetic field and a gate electric field allows the conductive properties of spin structures to be changed radically through the Fano resonance mechanism
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Вальков, Валерий Владимирович, Аксенов, Сергей Владимирович, Уланов Е. А.
Заглавие : Эффект Фано при туннелировании спин-поляризованного электрона через одиночную магнитную примесь
Место публикации : Физ. низких температур. - 2013. - Т. 39, Вып. 1. - С. 48-52
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Aksenov S. V., Ulanov E. A.
Заглавие : Fano effect upon tunneling of a spin-polarized electron through a single magnetic impurity
Место публикации : Low Temp. Phys. - 2013. - Vol. 39, no. 1. - P.35-38. - DOI 10.1063/1.4775746; \b Физика низких температур
Аннотация: The calculations of transport characteristics of a single magnetic impurity showed that the presence of different effective channels for electron transmission results in the Fano effect. It was noticed that the external magnetic field and gate voltage allow controlling the conducting properties, which are governed by the configuration interaction between the states of the system
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Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Maksimov D. N., Chesnokov I. Yu., Makarov D. V., Kolovsky A. R.
Заглавие : Landau-zener tunneling in 2d periodic structures in the presense of a gauge field
Коллективы : Euro-Asian Symposium "Trends in MAGnetism": Nanomagnetism
Место публикации : V Euro-Asian simposium "Trend in MAGnetism": Nanomagnetism: abstracts. - Vladivostok: FEFU, 2013. - С. 71. - ISBN 978-5-7444-3124-2
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zalipaev V. V., Maksimov D. N., Linton C. M., Kusmartsev F. V.
Заглавие : Spectrum of localized states in graphene quantum dots and wires
Место публикации : Phys. Lett. A. - 2013. - Vol. 377, Is. 3-4. - P.216-221. - ISSN 0375-9601, DOI 10.1016/j.physleta.2012.11.028
Ключевые слова (''Своб.индексиров.''): generalized bohr-sommerfeld quantization condition--graphene--high-energy eigenstates--semiclassical approximation--tunneling
Аннотация: We developed semiclassical method and show that any smooth potential in graphene describing elongated a quantum dot or wire may behave as a barrier or as a trapping well or as a double barrier potential, Fabry-Perot structure, for 1D Schrodinger equation. The energy spectrum of quantum wires has been found and compared with numerical simulations. We found that there are two types of localized states, stable and metastable, having finite life time. These life times are calculated, as is the form of the localized wave functions which are exponentially decaying away from the wire in the perpendicular direction. В© 2012 Elsevier B.V. All rights reserved.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zherikhina L. N., Tskhovrebov A. M., Klinkova L. A., Balaev D. A., Popkov S. I., Shaikhutdinov K. A.
Заглавие : Ba0.6K0.4BiO3 single crystal as a multiple Josephson system: New coherent effect?
Коллективы : International Conference on Low Temperature Physics
Место публикации : Journal of Physics: Conference Series. - 2012. - Vol. 400, Pt. 2. - Ст.022146. - P. - ISSN 1742-6588, DOI 10.1088/1742-6596/400/2/022146
Ключевые слова (''Своб.индексиров.''): antiphase--coherent effect--electric transport--high-t--inhomogeneous superconductors--josephson--josephson junctions--josephson tunneling--non-linear i-v--polycrystalline samples--superconducting gaps--superconducting state--low temperature effects--low temperature engineering--magnetic fields--superconductivity--single crystals
Аннотация: The existence of space inhomogeneous superconductor insulator state (SISIS) found out earlier in polycrystalline samples of high-Tc system Ba0.6K0.4BiO3 (Tc?30 K) is confirmed on Ba0.6K0.4BiO3 single crystal. At T* (T*<Tc, T*?17 K) the transition from the homogeneous superconducting state into the SISIS occurs. SISIS is characterized by the appearance of two gapes on the Fermi surface: semi- and superconducting, that are modulated in space in antiphase, the electric transport between superconducting regions being carried out due to Josephson tunneling. Thus the whole sample becomes a multiple Josephson system. Nonlinear I-V curves, depended on temperature and magnetic field, that are typical to a Josephson system, are observed on Ba0.6K0.4BiO3 single crystal at temperatures below T*. Besides, a step like peculiarity at the values of voltage of the order of one and two superconducting gaps shows up. These peculiarities are suppressed by magnetic field much earlier then critical current. Perhaps the last phenomenon is the consequence of "coherent" state of several successive Josephson junctions, appeared in the exfoliation state. В© Published under licence by IOP Publishing Ltd.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Karpov S. V., Semina P. N., Gavrilyuk A. P.
Заглавие : The role of the electron tunneling effect in the coagulation kinetics of polydisperse metal nanocolloids
Место публикации : Colloid J.: MAIK Nauka-Interperiodica / Springer, 2012. - Vol. 74, Is. 3. - P.305-312. - ISSN 1061-933X, DOI 10.1134/S1061933X12030052
Примечания : Cited References: 16. - Authors are thankful to G. A. Chiganova for discussions and helpful comments. Studies were carried out with the support of grants: the Presidium of RAS No 29 and No 31, OFN RAS III.9.5, IP SB RAS No 43, IP SB RAS (and SFU) No 101.
Предметные рубрики: PARTICLES
Аннотация: The energy of pair interactions between metal nanoparticles of different sizes is shown to be able to increase upon coagulation due to the additional electrostatic effect resulting from mutual heteropolar charging of the particles. The tunnel electron transfer occurring upon the collisions between particles of different sizes may be the reason for the charging. The transfer is caused by the dependence of the electron work function on the particle size. The electron transfer through the interparticle gap equalizes the Fermi levels in particles of different sizes and is associated with this dependence. Using the example of bimodal silver nanocolloids, it is shown that mutual heteropolar charging of particles with different sizes may accelerate the coagulation of polydisperse colloidal systems by an order of magnitude or more as compared with monodisperse systems, in which this effect is absent.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kolovsky A. R., Link J., Wimberger S.
Заглавие : Energetically constrained co-tunneling of cold atoms
Место публикации : New J. Phys.: IOP Publishing Ltd, 2012. - Vol. 14. - Ст.75002. - ISSN 1367-2630, DOI 10.1088/1367-2630/14/7/075002
Примечания : Cited References: 18. - The present project was supported by the Excellence Initiative (Enable Fund of the Faculty of Physics and Astronomy, Heidelberg University). Moreover, SW acknowledges financial support from the DFG through FOR760, the Helmholtz Alliance Program of the Helmholtz Association (contract number HA-216: Extremes of density and temperature: cosmic matter in the laboratory), and by the Heidelberg Graduate School of Fundamental Physics (grant number GSC 129/1) and AK acknowledges support from the Russian Foundation for Basic Research (project number 12-02-000094-a: Tunneling of the macroscopic quantum states) and by the Siberian Branch of RAS (project no. 29: Dynamics of atomic Bose-Einstein condensates in optical lattices). AK is very grateful for the hospitality of the Institute of Theoretical Physics of Heidelberg University.
Предметные рубрики: LATTICE
Аннотация: We study under-barrier tunneling for a pair of energetically bound bosonic atoms in an optical lattice with a barrier. We identify the conditions under which this exotic molecule tunnels as a point particle with the coordinate given by the bound pair center of mass and discuss the atomic co-tunneling beyond this regime. In particular, we quantitatively analyze resonantly enhanced co-tunneling, where two interacting atoms penetrate the barrier with higher probability than a single atom.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bulgakov E. N., Kolovsky A. R.
Заглавие : Induced tunneling and localization for a quantum particle in tilted two-dimensional lattices
Коллективы : Russian Academy of Sciences through the SB RAS [29]
Место публикации : Phys. Rev. B: American Physical Society, 2014. - Vol. 89, Is. 3. - Ст.035116. - ISSN 1098-0121, DOI 10.1103/PhysRevB.89.035116. - ISSN 1550-235X
Примечания : Cited References: 17. - The authors express their gratitude to D. N. Maksimov for useful remarks and acknowledge financial support of the Russian Academy of Sciences through the SB RAS integration project No. 29 Dynamics of atomic Bose-Einstein condensates in optical lattices.
Предметные рубрики: DYNAMIC LOCALIZATION
CHARGED-PARTICLE
OPTICAL LATTICE
ELECTRIC-FIELD
DIRAC POINTS
Аннотация: We consider a quantum particle in tilted two-dimensional lattices in the tight-binding approximations. We show that for certain lattice geometries the particle can freely move across the lattice in the direction perpendicular to the vector of the static force. This effect is argued to be analog of the photon-induced tunneling in driven one-dimensional lattices. We calculate the particle dispersion relation by using a method based on the Bogoliubov-Mitropolskii averaging technique from the theory of dynamical systems. This dispersion relation draws the analogy with driven one-dimensional lattices further by eventually showing band collapses when a control parameter is varied.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S., Romanova O. B., Янушкевич, Казимир Иосифович
Заглавие : Magnetoresistance effect in anion-substituted manganese chalcogenides
Место публикации : Phys. Status Solidi B. - 2015. - Vol. 252, Is. 8. - P.1792-1798. - ISSN 0370, DOI 10.1002/pssb.201451607. - ISSN 15213951 (eISSN)
Примечания : Cited References: 35. - This study was supported by the official assignment no. 114090470016.
Предметные рубрики: MAGNETIC-PROPERTIES
ELECTRONIC-STRUCTURE
SOLID-SOLUTIONS
MnTe
MnSe
CONDUCTIVITY
TRANSITION
Ключевые слова (''Своб.индексиров.''): electron tunneling--magnetic properties--magnetoresistance--semiconductors
Аннотация: The electric and magnetic properties of anion-substituted antiferromagnetic MnSe1-xTex (0.1≤x≤0.4) semiconductors in the 77-700K temperature range and magnetic fields under 1T are studied. In the MnSe1-xTex solid solutions, negative magnetoresistance in the vicinity of the Néel temperature for x=0.1 and for composition with x=0.2 in the paramagnetic range below 270K is revealed. A dependence of the magnetic susceptibility versus the prehistory of the samples is found. The model of localized spin-polarized electrons with the localization radius depending on the magnetic field is proposed for x=0.1. In the paramagnetic range, the negative magnetoresistance and the behavior of magnetic moment are a result of orbital glass formation.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Y., Mitskan V. A., Korovushkin M. M.
Заглавие : Anomalous superconductivity and superfluidity in repulsive fermion systems
Место публикации : Phys. Usp.: Turpion, 2015. - Vol. 58, Is. 8. - P.733-761. - ISSN 10637869 (ISSN), DOI 10.3367/UFNe.0185.201508a.0785
Примечания : Cited References: 369. - We are grateful to M A Baranov, A V Chubukov, D V Efremov, M V Feigel'man, V V Kabanov, K I Kugel', M S Marienko, N M Plakida, N V Prokorev, A Ya Tzalenchuk, and V V Val'kov for the fruitful discussions and constant attention to our work. The work was supported by the Russian Foundation for Basic Research (project nos. 14-02-00058 and 14-02-31237). M Yu K thanks the Program of Basic Research of the National Research University Higher School of Economics for support. The work of MM K was supported by grant of the President of the Russian Federation (SP-1361.2015.1) and the Dinasty Foundation
Предметные рубрики: HEXAGONAL BORON-NITRIDE
SCANNING-TUNNELING-MICROSCOPY
2-DIMENSIONAL HUBBARD-MODEL
HIGH-TC SUPERCONDUCTIVITY
ELECTRON-ENERGY SPECTRUM
P-WAVE SUPERCONDUCTIVITY
DOUBLE-LAYER GRAPHENE
2D KONDO-LATTICE
GROUND-STATE
TRANSITION-TEMPERATURE
Ключевые слова (''Своб.индексиров.''): anomalous superconductivity--kohn-luttinger mechanism--superfluidity--repulsive fermi gas--hubbard and t-jmodel--shubin vonsovsky model--graphene monolayer--graphene bilayer
Аннотация: We discuss the mechanisms of unconventional superconductivity and superfluidity in 3D and 2D fermionic systems with purely repulsive interaction at low densities. We construct phase diagrams of these systems and find the areas of the superconducting state in free space, as well as on the lattice in the framework of the Fermi-gas model with hard-core repulsion, the Hubbard model, the Shubin-Vonsovsky model, and the t-J model. We demonstrate that the critical superconducting temperature can be greatly increased in the spin-polarized case or in a two-band situation already at low densities. The proposed theory is based on the Kohn-Luttinger mechanism or its generalizations and explains or predicts anomalous p-, d-, and f-wave pairing in various materials, such as high-temperature superconductors, the idealized monolayer and bilayer of doped graphene, heavy-fermion systems, layered organic superconductors, superfluid 3He, spin-polarized 3He mixtures in 4He, ultracold quantum gases in magnetic traps, and optical lattices.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Makarov I. A., Shneyder E. I.
Заглавие : Effect of interlayer tunneling on the electronic structure of bilayer cuprates and quantum phase transitions in carrier concentration and high magnetic field
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2011. - Vol. 112, Is. 2. - P288-302. - ISSN 1063-7761, DOI 10.1134/S106377611005119X
Примечания : Cited References: 64. - This study was supported financially by the program "Quantum Physics of Condensed Media" of the Presidium of the Russian Academy of Sciences (project no. 5.7), the integration projects of the Siberian Branch and the Ural Division of the Russian Academy of Sciences (project no. 40), the Russian Foundation for Basic Research (project no. 09-02-00127), the President of the Russian Federation (grant no. MK-1683.2010.2), and the Federal Target Program P891.
Предметные рубрики: T-J MODEL
HIGH-TEMPERATURE SUPERCONDUCTORS
DIMENSIONAL HUBBARD-MODEL
FERMI-SURFACE
COPPER OXIDES
GROUND-STATE
CUO2 PLANES
SPECTRUM
BAND
NMR
Ключевые слова (''Своб.индексиров.''): antibonding--bi-layer--bilayer cuprates--complex sequences--cuprates--doping levels--external magnetic field--field magnitude--hartree-fock approximations--high magnetic fields--lifshitz transition--main effect--orbitals--perturbation theory--quantum phase transitions--quantum transitions--single-layer structure--theoretical study--unit cells--carrier concentration--copper compounds--density functional theory--electronic properties--electronic structure--hartree approximation--magnetic fields--perturbation techniques--phase transitions--surface structure--quantum theory
Аннотация: We present a theoretical study of the electronic structure of bilayer HTSC cuprates and its evolution under doping and in a high magnetic field. Analysis is based on the t-t'-taEuro(3)-J* model in the generalized Hartree-Fock approximation. Possibility of tunneling between CuO2 layers is taken into account in the form of a nonzero integral of hopping between the orbitals of adjacent planes and is included in the scheme of the cluster form of perturbation theory. The main effect of the coupling between two CuO2 layers in a unit cell is the bilayer splitting manifested in the presence of antibonding and bonding bands formed by a combination of identical bands of the layers themselves. A change in the doping level induces reconstruction of the band structure and the Fermi surface, which gives rise to a number of quantum phase transitions. A high external magnetic field leads to a fundamentally different form of electronic structure. Quantum phase transitions in the field are observed not only under doping, but also upon a variation of the field magnitude. Because of tunneling between the layers, quantum transitions are also split; as a result, a more complex sequence of the Lifshitz transitions than in single-layer structures is observed.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kolovsky A. R.
Заглавие : Creating artificial magnetic fields for cold atoms by photon-assisted tunneling
Место публикации : Europhys. Lett. - 2011. - Vol. 93, Is. 2. - Ст.20003. - ISSN 0295-5075, DOI 10.1209/0295-5075/93/20003
Примечания : Cited References: 20. - This work was supported by Russian Foundation for Basic Research, grant RFBR-10-02-00171-a.
Предметные рубрики: BLOCH OSCILLATIONS
OPTICAL LATTICES
NEUTRAL ATOMS
Аннотация: This paper proposes a simple setup for introducing an artificial magnetic field for neutral atoms in 2D optical lattices. This setup is based on the phenomenon of photon-assisted tunneling and involves a low-frequency periodic driving of the optical lattice. This low-frequency driving does not affect the electronic structure of the atom and can be easily realized by the same means which are employed to create the lattice. We also address the problem of detecting this effective magnetic field. In particular, we study the center-of-mass wave packet dynamics, which is shown to exhibit certain features of cyclotron dynamics of a classical charged particle. Copyright (C) EPLA, 2011
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Dubrovskiy A. A., Shaykhutdinov K. A., Popkov S. I., Petrov M. I.
Заглавие : Peculiarities of the time evolution of magnetoresistance of granular HTSC in a constant applied magnetic field
Коллективы :
Место публикации : Solid State Commun. - 2008. - Vol. 147, Is. 7-8. - P.284-287. - ISSN 0038-1098, DOI 10.1016/j.ssc.2008.05.044
Примечания : Cited References: 17. - This work was Supported by program "Quantum macrophysics" No. 3.4 of RAS and integration project No. 3.4 of SB RAS and in part by KSF, grant 18G011. D.A.B. and A.A.D. acknowledge the Russian Science Support Foundation.
Предметные рубрики: CRITICAL-STATE
SUPERCONDUCTORS
COMPOSITES
HYSTERESIS
RESISTANCE
Ключевые слова (''Своб.индексиров.''): superconductors--flux pinning and creep--tunneling--superconductors--flux pinning and creep--tunneling--agricultural products--carbon fiber reinforced plastics--copper oxides--electric conductivity--electric resistance--evolutionary algorithms--ferromagnetism--galvanomagnetic effects--grain (agricultural product)--health--hysteresis--magnetic devices--magnetic field effects--magnetic field measurement--magnetic fields--magnetic materials--magnetoelectronics--magnetoresistance--semiconductor metal boundaries--superconducting magnets--superconductivity--yttrium barium copper oxides--p ,p ,t measurements--applied (co)--applied magnetic fields--constant magnetic field (cmf)--elsevier (co)--evolution (co)--external fields--field induced--flux creep--hysteretic behavior--josephson couplings--low magnetic fields--magnetic (ce)--poly crystalline--superconducting grains--time evolutions--time relaxation--magnetism
Аннотация: The time evolution of the magnetoresistance of bulk YBCO + CuO composites at T = 4.2 K in constant applied magnetic fields was studied to clarify the mechanism of hysteretic behavior of magnetoresistance R(H) of granular HTSC. The composites represent "model" granular HTSC with weakened Josephson coupling between superconducting (YBCO) crystallites. It was found for the first time that on the ascending branch of R(H) dependence, the resistance at H = const decreased with time while on the descending branch, the resistance increased with time in ail applied constant magnetic field. In the range of low magnetic fields (below the minimum point of the descending branch of the R(H) dependence), the resistance at H const decreased again. Similar measurements performed oil pure polycrystalline YBCO at T = 77.4 K have shown that the behavior of evolution of resistance with time is similar to that observed for the composite. This proves the peculiarity of time evolution of maignetoresistance to be a common feature of granular HTSCs. The behavior revealed is well described by the model Of granular HTSC, where the intergrain media is in an effective magnetic field which is the superposition of the external field and the field induced by superconducting grains. The time evolution of resistance reflects the time relaxation of magnetization of HTSC grains due to the intragrain flux Creep Processes. (C) 2008 Elsevier Ltd. All rights reserved.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Nesterov A. I., Ovchinnikov S. G.
Заглавие : Geometric phases and quantum phase transitions in open systems
Место публикации : Phys. Rev. E: AMER PHYSICAL SOC, 2008. - Vol. 78, Is. 1. - Ст.15202. - ISSN 1539-3755, DOI 10.1103/PhysRevE.78.015202
Примечания : Cited References: 29
Предметные рубрики: POINTS
DEGENERACIES
Ключевые слова (''Своб.индексиров.''): chlorine compounds--electron tunneling--ferromagnetism--ising model--magnetic fields--magnetism--open systems--quantum electronics--quantum optics--sedimentation--effective hamiltonian--eigenvalues--first orders--geometric phase--geometric phases--ground-state--hermitian--one-dimensional--open quantum systems--quantum phase transition--quantum phase transitions--transverse-magnetic fields--phase transitions
Аннотация: The relationship is established between quantum phase transitions and complex geometric phases for open quantum systems governed by a non-Hermitian effective Hamiltonian with accidental crossing of the eigenvalues. In particular, the geometric phase associated with the ground state of the one-dimensional dissipative Ising model in a transverse magnetic field is evaluated, and it is demonstrated that the related quantum phase transition is of the first order.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Fransson J., Sandalov I., Eriksson O.
Заглавие : A perfect spin-filter quantum dot system
Место публикации : J. Phys.: Condens. Matter: IOP PUBLISHING LTD, 2004. - Vol. 16, Is. 16. - P.L249-L254. - ISSN 0953-8984, DOI 10.1088/0953-8984/16/16/L03
Примечания : Cited References: 39
Предметные рубрики: NARROW ENERGY BANDS
ELECTRON CORRELATIONS
MAGNETIC-FIELD
MAGNETOTRANSPORT
CONDUCTANCE
RESISTANCE
BARRIER
FORMULA
VALVE
LIMIT
Ключевые слова (''Своб.индексиров.''): electric potential--electron tunneling--magnetic couplings--magnetic fields--magnetic filters--transport properties--electron correlations--magnetic contacts--source-drain voltage--spin projections--semiconductor quantum dots
Аннотация: The discovery of a novel effect in the transport through a QD spin-dependently coupled to magnetic contacts is reported. For a finite range of source-drain voltages the spin projections of the current cancel exactly, resulting in a completely suppressed output current. The spin down current behaves as one normally expects whereas the spin up current becomes negative. As the source-drain voltage is increased the spin up current eventually becomes positive. Thus, tuning the source-drain voltage such that the spin up current vanishes will result in a perfect spin filter.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Fransson J., Holmstrom E., Eriksson O., Sandalov I.
Заглавие : Theory of spin filtering through quantum dots
Место публикации : Phys. Rev. B: AMER PHYSICAL SOC, 2003. - Vol. 67, Is. 20. - Ст.205310. - ISSN 1098-0121, DOI 10.1103/PhysRevB.67.205310
Примечания : Cited References: 28
Предметные рубрики: DEPENDENT TUNNELING JUNCTIONS
NARROW ENERGY BANDS
ELECTRON CORRELATIONS
MAGNETORESISTANCE
BARRIER
POLARIZATION
Аннотация: Using a nonequilibrium diagram technique for Hubbard operator Green functions combined with a generalization of the transfer Hamiltonian formalism, we calculate the transport through a magnetic quantum dot system with spin-dependent couplings to the contacts. In specific regimes of the parameter space the spin-dependent tunnel current becomes more than 99.95% spin polarized, suggesting that a device thus constructed can be used in spin-filter applications. First-principles electronic structure calculations show the existence of nanostructured systems, such as, e.g., MgO/Fe/Pd(5)/Fe/MgO (001), with the desired properties in the direction of the current.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Volkov N. V., Patrin G. S., Petrakovskii G. A., Sablina K. A., Ovchinnikov S. G., Varnakov S. N.
Заглавие : Tunneling magnetoresistance in a Eu0.7Pb0.3MnO3 (single crystal)-Fe (film) structure
Место публикации : Tech. Phys. Lett.: AMER INST PHYSICS, 2003. - Vol. 29, Is. 3. - P200-202. - ISSN 1063-7850, DOI 10.1134/1.1565633
Примечания : Cited References: 7
Аннотация: We have studied the magnetoresistive properties of a structure comprising single crystal manganite Eu0.7Pb0.3MnO3 covered with an epitaxial iron film. At temperatures below T-C of the manganite crystal, the structure exhibits positive magnetoresistance. The behavior of the resistance as a function of the magnetic field is characteristic of a tunneling junction with ferromagnetic electrodes separated by a thin insulating film. The observed effect is related to the formation of a transition layer at the manganite-Fe interface, which is depleted of oxygen and possesses dielectric properties. The sensitivity of the resistance with respect to the magnetic field is determined both by the negative magnetoresistance of the manganite crystal and by the tunneling contribution to the conductivity, whereby the tunneling current depends on the mutual orientation of magnetic moments of the electrodes (Eu0.7Pb0.3MnO3 crystal and Fe film). (C) 2003 MAIK "Nauka/Interperiodica".
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mendez-Bermudez J. A., Luna-Acosta G. A., Seba P., Pichugin K. N.
Заглавие : Understanding quantum scattering properties in terms of purely classical dynamics: Two-dimensional open chaotic billiards
Место публикации : Phys. Rev. E: AMER PHYSICAL SOC, 2002. - Vol. 66, Is. 4. - Ст.46207. - ISSN 1539-3755, DOI 10.1103/PhysRevE.66.046207
Примечания : Cited References: 34
Предметные рубрики: BALLISTIC-TRANSPORT
POINCARE SECTIONS
CAVITIES
EIGENFUNCTIONS
LOCALIZATION
CHANNEL
Ключевые слова (''Своб.индексиров.''): chaos theory--electron tunneling--laser applications--nonlinear systems--probability--waveguide components--chaotic motion--microlasers--quantum scattering--scattering probability--quantum theory--article
Аннотация: We study classical and quantum scattering properties of particles in the ballistic regime in two-dimensional chaotic billiards that are models of electron- or micro-waveguides. To this end we construct the purely classical counterparts of the scattering probability (SP) matrix \S(n,m)\(2) and Husimi distributions specializing to the case of mixed chaotic motion (incomplete horseshoe). Comparison between classical and quantum quantities allows us to discover the purely classical dynamical origin of certain general as well as particular features that appear in the quantum description of the system. On the other hand, at certain values of energy the tunneling of the wave function into classically forbidden regions produces striking differences between the classical and quantum quantities. A potential application of this phenomenon in the field of microlasers is discussed briefly. We also see the manifestation of whispering gallery orbits as a self-similar structure in the transmission part of the classical SP matrix.
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