The Experts below are selected from a list of 80349 Experts worldwide ranked by ideXlab platform
I. D. Vagner - One of the best experts on this subject based on the ideXlab platform.
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Magnetization of nuclear-Spin-Polarization-induced quantum ring
Physica E-low-dimensional Systems & Nanostructures, 2004Co-Authors: S.n Shevchenko, Yu. V. Pershin, I. D. VagnerAbstract:Abstract Properties of a nuclear-Spin-Polarization-induced quantum ring (NSPI QR) are studied theoretically. In the proposed system a local nuclear Spin Polarization creates an effective magnetic field which confines the electrons with the Spins opposite to this field to the regions of maximal nuclear Spin Polarization. We investigate the electron energy spectrum and the magnetic response of NSPI QR and their evolution in time due to the nuclear Spin diffusion and relaxation.
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Magnetization of nuclear-Spin-Polarization-induced quantum ring
Physica E: Low-dimensional Systems and Nanostructures, 2004Co-Authors: S.n Shevchenko, Yu. V. Pershin, I. D. VagnerAbstract:Properties of a Nuclear-Spin-Polarization-Induced Quantum Ring (NSPI QR) are studied theoretically. In the proposed system a local nuclear Spin Polarization creates an effective hyperfine field which confines the electrons with the Spins opposite to the hyperfine field to the regions of maximal nuclear Spin Polarization. We investigate the electron energy spectrum and the magnetic response of NSPI QR and their evolution in time due to the nuclear Spin diffusion and relaxation
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Electronic transport through nuclear-Spin-Polarization-induced quantum wire
Physical Review A, 2002Co-Authors: Yu. V. Pershin, S.n Shevchenko, I. D. Vagner, P. WyderAbstract:Electron transport in a new low-dimensional structure - the nuclear Spin Polarization induced quantum wire (NSPI QW) is theoretically studied. In the proposed system the local nuclear Spin Polarization creates the effective hyperfine field which confines the electrons with the Spins opposite to the hyperfine field to the regions of maximal nuclear Spin Polarization. The influence of the nuclear Spin relaxation and diffusion on the electron energy spectrum and on the conductance of the quantum wire is calculated and the experimental feasibility is discussed.
S.n Shevchenko - One of the best experts on this subject based on the ideXlab platform.
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Magnetization of nuclear-Spin-Polarization-induced quantum ring
Physica E-low-dimensional Systems & Nanostructures, 2004Co-Authors: S.n Shevchenko, Yu. V. Pershin, I. D. VagnerAbstract:Abstract Properties of a nuclear-Spin-Polarization-induced quantum ring (NSPI QR) are studied theoretically. In the proposed system a local nuclear Spin Polarization creates an effective magnetic field which confines the electrons with the Spins opposite to this field to the regions of maximal nuclear Spin Polarization. We investigate the electron energy spectrum and the magnetic response of NSPI QR and their evolution in time due to the nuclear Spin diffusion and relaxation.
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Magnetization of nuclear-Spin-Polarization-induced quantum ring
Physica E: Low-dimensional Systems and Nanostructures, 2004Co-Authors: S.n Shevchenko, Yu. V. Pershin, I. D. VagnerAbstract:Properties of a Nuclear-Spin-Polarization-Induced Quantum Ring (NSPI QR) are studied theoretically. In the proposed system a local nuclear Spin Polarization creates an effective hyperfine field which confines the electrons with the Spins opposite to the hyperfine field to the regions of maximal nuclear Spin Polarization. We investigate the electron energy spectrum and the magnetic response of NSPI QR and their evolution in time due to the nuclear Spin diffusion and relaxation
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Electronic transport through nuclear-Spin-Polarization-induced quantum wire
Physical Review A, 2002Co-Authors: Yu. V. Pershin, S.n Shevchenko, I. D. Vagner, P. WyderAbstract:Electron transport in a new low-dimensional structure - the nuclear Spin Polarization induced quantum wire (NSPI QW) is theoretically studied. In the proposed system the local nuclear Spin Polarization creates the effective hyperfine field which confines the electrons with the Spins opposite to the hyperfine field to the regions of maximal nuclear Spin Polarization. The influence of the nuclear Spin relaxation and diffusion on the electron energy spectrum and on the conductance of the quantum wire is calculated and the experimental feasibility is discussed.
Yu. V. Pershin - One of the best experts on this subject based on the ideXlab platform.
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Magnetization of nuclear-Spin-Polarization-induced quantum ring
Physica E-low-dimensional Systems & Nanostructures, 2004Co-Authors: S.n Shevchenko, Yu. V. Pershin, I. D. VagnerAbstract:Abstract Properties of a nuclear-Spin-Polarization-induced quantum ring (NSPI QR) are studied theoretically. In the proposed system a local nuclear Spin Polarization creates an effective magnetic field which confines the electrons with the Spins opposite to this field to the regions of maximal nuclear Spin Polarization. We investigate the electron energy spectrum and the magnetic response of NSPI QR and their evolution in time due to the nuclear Spin diffusion and relaxation.
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Magnetization of nuclear-Spin-Polarization-induced quantum ring
Physica E: Low-dimensional Systems and Nanostructures, 2004Co-Authors: S.n Shevchenko, Yu. V. Pershin, I. D. VagnerAbstract:Properties of a Nuclear-Spin-Polarization-Induced Quantum Ring (NSPI QR) are studied theoretically. In the proposed system a local nuclear Spin Polarization creates an effective hyperfine field which confines the electrons with the Spins opposite to the hyperfine field to the regions of maximal nuclear Spin Polarization. We investigate the electron energy spectrum and the magnetic response of NSPI QR and their evolution in time due to the nuclear Spin diffusion and relaxation
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Accumulation of Electron Spin Polarization at Semiconductor Interfaces
Physical Review B, 2003Co-Authors: Yu. V. PershinAbstract:In this Brief Report we study theoretically the propagation of electron Spin Polarization through an interface separating two n-type semiconductor regions within the two-component drift-diffusion model in an applied electric field. It is assumed that inhomogeneous Spin Polarization is created locally by a continuous source of Spin Polarization and is driven through the boundary by the electric field. The Spin Polarization distribution is calculated analytically. We find that for specific values of parameters describing the system, the electron Spin Polarization is accumulated near the interface. A simple analytical expression for the amplitude of Spin accumulation as a function of the system parameters is found. The obtained results will be useful in designing new Spintronic devices.
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Focusing of Spin Polarization in semiconductors by inhomogeneous doping.
Physical review letters, 2003Co-Authors: Yu. V. Pershin, Vladimir PrivmanAbstract:We study the evolution and distribution of nonequilibrium electron Spin Polarization in n-type semiconductors within the two-component drift-diffusion model in an applied electric field. Propagation of Spin-polarized electrons through a boundary between two semiconductor regions with different doping levels is considered. We assume that inhomogeneous Spin Polarization is created locally and driven through the boundary by the electric field. We show that an initially created narrow region of Spin Polarization can be further compressed and amplified near the boundary. Since the boundary involves variation of doping but no real interface between two semiconductor materials, no significant Spin Polarization loss is expected. The proposed mechanism will be therefore useful in designing new Spintronic devices.
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Focusing of Spin Polarization in semiconductors by inhomogeneous doping.
Physical Review Letters, 2003Co-Authors: Yu. V. Pershin, Vladimir PrivmanAbstract:We study the evolution and distribution of nonequilibrium electron Spin Polarization in n-type semiconductors within the two-component drift-diffusion model in an applied electric field. Propagation of Spin-polarized electrons through a boundary between two semiconductor regions with different doping levels is considered. We assume that inhomogeneous Spin Polarization is created locally and driven through the boundary by the electric field. We show that an initially created narrow region of Spin Polarization can be further compressed and amplified near the boundary. Since the boundary involves variation of doping but no real interface between two semiconductor materials, no significant Spin Polarization loss is expected. The proposed mechanism will be therefore useful in designing new Spintronic devices. DOI: 10.1103/PhysRevLett.90.256602
Jean-paul Malrieu - One of the best experts on this subject based on the ideXlab platform.
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Improved evaluation of Spin-Polarization energy contributions using broken-symmetry calculations.
The Journal of chemical physics, 2020Co-Authors: Grégoire David, Nicolas Ferré, Georges Trinquier, Jean-paul MalrieuAbstract:Spin-Polarization effects may play an important role in free radicals and in the magnetic coupling between radical centers. Starting from restricted open-shell calculations, i.e., a closed-shell description of the non-magnetic core electrons, a low-order perturbation expansion identifies the Spin-Polarization contribution to the energy of mono-radicals and to singlet-triplet energy differences in diradicals. Broken-symmetry (BS) single-determinant calculations introduce only a fraction of Spin-Polarization effects, and in a biased manner, since BS determinants are not Spin eigenfunctions. We propose a simple technique to correctly evaluate Spin-Polarization energies by taking into account the effect of Spin-flip components on one-hole one-particle excited configurations. Spin-decontamination corrections are shown to play a non-negligible role in the BS evaluation of bond energies. The importance of Spin decontamination is illustrated in cases for which Spin Polarization is the leading contribution to the singlet-triplet gap, which characterizes twisted conjugated double bonds and disjoint diradicals.
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Improved evaluation of Spin-Polarization energy contributions using broken-symmetry calculations
Journal of Chemical Physics, 2020Co-Authors: Grégoire David, Nicolas Ferré, Georges Trinquier, Jean-paul MalrieuAbstract:Spin-Polarization effects may play an important role in free radicals and in the magnetic coupling between radical centers. Starting from restricted open-shell calculations, i.e. a closed-shell description of the non-magnetic core electrons, a low-order perturbation expansion identifies the Spin Polarization contribution to the energy of mono-radicals and to singlet-triplet energy differences in diradicals. Broken-symmetry (BS) single-determinant calculations introduce only a fraction of Spin Polarization effects, and in a biased manner, since BS determinants are not Spin eigenfunctions. We propose a simple technique to correctly evaluate Spin-Polarization energies by taking into account the effect of Spin-flip components of one-hole one-particle excited configurations. Spin-decontamination corrections is shown to play a non-negligible role in BS evaluation of bond energies. The importance of Spin-decontamination is illustrated on cases for which Spin Polarization is the leading contribution to the singlet-triplet gap, what characterizes twisted conjugated double-bonds and disjoint diradicals.
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Spin Polarization as an electronic cooperative effect
Journal of Chemical Physics, 2020Co-Authors: Nadia Ben Amor, Georges Trinquier, Camille Nous, Jean-paul MalrieuAbstract:Taking as an example the simple CH3 radical, this work demonstrates the cooperative character of the Spin-Polarization phenomenon of the closed-shell core in free radicals. Spin Polarization of CH σ bonds is not additive here, as Spin Polarization of one bond enhances that of the next bond. This cooperativity is demonstrated by a series of configuration interaction calculations converging to the full valence limit and is rationalized by analytic developments. The same phenomenon is shown to take place in those diradicals where Spin Polarization plays a major role, as illustrated in square planar carbo-cyclobutadiene C12H4. The treatment of cooperativity represents a challenge for usual post-Hatree-Fock methods.
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Spin Polarization as an electronic cooperative effect
Journal of Chemical Physics, 2020Co-Authors: Nadia Ben Amor, Georges Trinquier, Camille Nous, Jean-paul MalrieuAbstract:The density matrix renormalization group in chemistry and molecular physics: Recent developments and new challenges The Journal of Chemical Physics 152, 040903 (2020); https://doi. ABSTRACT Taking as an example the simple CH 3 radical, this work demonstrates the cooperative character of the Spin-Polarization phenomenon of the closed-shell core in free radicals. Spin Polarization of CH σ bonds is not additive here, as Spin Polarization of one bond enhances that of the next bond. This cooperativity is demonstrated by a series of configuration interaction calculations converging to the full valence limit and is rationalized by analytic developments. The same phenomenon is shown to take place in those diradicals where Spin Polarization plays a major role, as illustrated in square planar carbo-cyclobutadiene C 12 H 4. The treatment of cooperativity represents a challenge for usual post-Hatree-Fock methods. Published under license by AIP Publishing. https://doi.
Yoshiro Hirayama - One of the best experts on this subject based on the ideXlab platform.
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Optically Induced Nuclear Spin Polarization in the Quantum Hall Regime: The Effect of Electron Spin Polarization through Exciton and Trion Excitations.
Physical review letters, 2015Co-Authors: K. Akiba, S. Kanasugi, Tatsuro Yuge, K. Nagase, Yoshiro HirayamaAbstract:We study nuclear Spin Polarization in the quantum Hall regime through the optically pumped electron Spin Polarization in the lowest Landau level. The nuclear Spin Polarization is measured as a nuclear magnetic field B(N) by means of the sensitive resistive detection. We find the dependence of B(N) on the filling factor nonmonotonic. The comprehensive measurements of B(N) with the help of the circularly polarized photoluminescence measurements indicate the participation of the photoexcited complexes, i.e., the exciton and trion (charged exciton), in nuclear Spin Polarization. On the basis of a novel estimation method of the equilibrium electron Spin Polarization, we analyze the experimental data and conclude that the filling factor dependence of B(N) is understood by the effect of electron Spin Polarization through excitons and trions.
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Optically Induced Nuclear Spin Polarization in the Quantum Hall Regime: The Effect of Electron Spin Polarization through Exciton and Trion Excitations
arXiv: Mesoscale and Nanoscale Physics, 2014Co-Authors: K. Akiba, S. Kanasugi, Tatsuro Yuge, K. Nagase, Yoshiro HirayamaAbstract:We study nuclear Spin Polarization in the quantum Hall regime through the optically pumped electron Spin Polarization in the lowest Landau level. The nuclear Spin Polarization is measured as a nuclear magnetic field $B_N$ by means of the sensitive resistive detection. We find the dependence of $B_N$ on filling factor unmonotonous. The comprehensive measurements of $B_N$ with the help of the circularly polarized photoluminescence measurements indicate the participation of the photo-excited complexes i.e., the exciton and trion (charged exciton), in nuclear Spin Polarization. On the basis of a novel estimation method of the equilibrium electron Spin Polarization, we analyze the experimental data and conclude that the filling factor dependence of $B_N$ is understood by the effect of electron Spin Polarization through excitons and trions.
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High-sensitive optical measurement of Spin Polarization in a quantum Hall system
Journal of Physics: Conference Series, 2011Co-Authors: H. Ito, Yoshiro Hirayama, Takehiro Yamazaki, Daisuke Fukuoka, Kenichi Oto, K. Muro, N. KumadaAbstract:Spin Polarization measurement is important for the study of a variety of Spin states in quantum Hall system. Kerr rotation is proportional to Spin Polarization, so we developed a high sensitive measurement of Kerr rotation by using homodyne detection and a variety of modulation techniques. Furthermore, we developed Kerr rotation spectra measurement system base on the multi-channel homodyne detection, which enables the assignment of the optical transitions and semi-quantitative estimation of Spin Polarization by integrating the spectra over the specific optical transition. The Spin Polarization presents a rapid Spin dePolarization on both sides of ? = 1 due to Skyrmionic excitation. However the top of Spin Polarization presents a narrow flat region. Furthermore the Spin Polarization around ? = 3 also shows a rapid Spin dePolarization which suggest the existence of Skyrmion at higher odd filling factor.
