Spin Hall effect in clean two-dimensional electron gases with rashba spin-orbit coupling
TL;DR: In this article, the spin polarization induced by a current flow in clean two-dimensional electron gases with Rashba spin-orbit coupling was studied and it was shown that spin polarization can be strongly enhanced.
Abstract: We study the spin polarization induced by a current flow in clean two-dimensional electron gases with Rashba spin-orbit coupling. This geometric effect originates from special properties of the electron's scattering at the edges of the sample. In wide samples, the spin polarization has its largest value at low energies (close to the bottom of the band) and goes to zero at higher energies. In this case, the spin polarization is dominated by the presence of evanescent modes which have an explicit spin component outside the plane. In quantum wires, on the other hand, the spin polarization is dominated by interference effects induced by multiple scattering at the edges. Here, the spin polarization is quite sensitive to the value of the Fermi energy, especially close to the point where a new channel opens up. We analyzed different geometries and found that the spin polarization can be strongly enhanced.
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TL;DR: In this paper, the amplitude's asymmetry of the spin-split transverse electron focusing peak is used to extract information about the electron's spin polarization, which can be used to detect the one-body effect in quantum point contacts.
Abstract: It has been predicted recently that an electron beam can be polarized when it flows adiabatically through a quantum point contact in a system with spin-orbit interaction. Here, we show that a simple transverse electron focusing setup can be used to detect such polarized current. It uses the amplitude's asymmetry of the spin-split transverse electron focusing peak to extract information about the electron's spin polarization. On the other hand, and depending on the quantum point contact geometry, including this one-body effect can be important when using the focusing setup to study many-body effects in quantum point contacts.
36 citations
TL;DR: In this article, the total spectrum of electron states in a bounded two-dimensional electron gas with spin-orbit interaction contains two types of evanescent states lying in different energy ranges: the first type states fill in a gap, which opens in the band of propagating spin-splitted states if tangential momentum is nonzero.
Abstract: We find that the total spectrum of electron states in a bounded two-dimensional electron gas with spin-orbit interaction contains two types of evanescent states lying in different energy ranges. The first-type states fill in a gap, which opens in the band of propagating spin-splitted states if tangential momentum is nonzero. They are described by a pure imaginary wave vector. The states of second type lie in the forbidden band. They are described by a complex wave vector. These states give rise to unusual features of the electron transmission through a lateral potential barrier with spin-orbit interaction, such as an oscillatory dependence of the tunneling coefficient on the barrier width and electron energy. However, of most interest is the spin polarization of an unpolarized incident electron flow. Particularly, the transmitted electron current acquires spin polarization even if the distribution function of incident electrons is symmetric with respect to the transverse momentum. The polarization efficiency is an oscillatory function of the barrier width. Spin filtering is most effective if the Fermi energy is close to the barrier height.
35 citations
TL;DR: In this article, the spin-orbit coupling in two-dimensional (2D) electron systems with a potential gradient parallel to the 2D plane exerts a spindependent transverse force on moving electrons while conserving their spins.
Abstract: We show that the spin-orbit coupling in two-dimensional (2D) electron systems with a potential gradient parallel to the 2D plane exerts a spin-dependent transverse force on moving electrons while conserving their spins Due to the spin conservation, the standard continuity equation holds between spin density and spin current Using numerical calculations based on the nonequilibrium Green's function formalism, we demonstrate for crossed quantum wires with a harmonic confining potential in the ballistic limit that transverse spin separation and spin Hall current are generated in response to a longitudinal charge current
35 citations
TL;DR: The present review summarizes recent theoretical and experimental efforts to reveal the microscopic structure and mechanisms of spin-orbit driven phenomena with the focus on angle and spin-resolved photoemission and scanning tunneling microscopy.
Abstract: Spin-orbit interaction gives rise to a splitting of surface states via the Rashba effect, and in topological insulators it leads to the existence of topological surface states. The resulting k(//) momentum separation between states with the opposite spin underlies a wide range of new phenomena at surfaces and interfaces, such as spin transfer, spin accumulation, spin-to-charge current conversion, which are interesting for fundamental science and may become the basis for a breakthrough in the spintronic technology. The present review summarizes recent theoretical and experimental efforts to reveal the microscopic structure and mechanisms of spin-orbit driven phenomena with the focus on angle and spin-resolved photoemission and scanning tunneling microscopy.
33 citations
TL;DR: In this article, boundary conditions for the coupled spin-charge diffusion equations at a transmitting interface between two-dimensional electron systems with different strengths of the Rashba spin-orbit coupling and an electric field parallel to the interface were derived.
Abstract: We derive boundary conditions for the coupled spin-charge diffusion equations at a transmitting interface between two-dimensional electron systems with different strengths of the Rashba spin-orbit (SO) coupling $\ensuremath{\alpha}$ and an electric field parallel to the interface. We consider the limit where the spin-diffusion length ${l}_{s}$ is long compared to the electron mean-free path $l$ and assume that $\ensuremath{\alpha}$ changes discontinuously on the scale of ${l}_{s}$. We find that the spin density is also discontinuous on the scale of ${l}_{s}$. In the case where the electron mobility is constant across the interface, this leads to the complete suppression of the expected spin injection from a region with $\ensuremath{\alpha}\ensuremath{
e}0$ into a non-SO region with $\ensuremath{\alpha}=0$.
24 citations
References
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01 Jan 1995TL;DR: In this article, preliminary concepts of conductance from transmission, S-matrix and Green's function formalism are discussed. And double-barrier tunnelling is considered.
Abstract: 1. Preliminary concepts 2. Conductance from transmission 3. Transmission function, S-matrix and Green's functions 4. Quantum Hall effect 5. Localisation and fluctuations 6. Double-barrier tunnelling 7. Optical analogies 8. Non-equilibrium Green's function formalism.
5,447 citations
01 May 1997
TL;DR: In this article, preliminary concepts of conductance from transmission, S-matrix and Green's function formalism are discussed. And double-barrier tunnelling is considered.
Abstract: 1. Preliminary concepts 2. Conductance from transmission 3. Transmission function, S-matrix and Green's functions 4. Quantum Hall effect 5. Localisation and fluctuations 6. Double-barrier tunnelling 7. Optical analogies 8. Non-equilibrium Green's function formalism.
4,224 citations
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TL;DR: In this paper, it is proposed that when a charge current circulates in a paramagnetic metal, a transverse spin imbalance will be generated, giving rise to a spin Hall voltage, in the absence of charge current and magnetic field.
Abstract: It is proposed that when a charge current circulates in a paramagnetic metal a transverse spin imbalance will be generated, giving rise to a ``spin Hall voltage.'' Similarly, it is proposed that when a spin current circulates a transverse charge imbalance will be generated, giving rise to a Hall voltage, in the absence of charge current and magnetic field. Based on these principles we propose an experiment to generate and detect a spin current in a paramagnetic metal.
2,337 citations
TL;DR: In this paper, the authors detected and imaged electron-spin polarization near the edges of a semiconductor channel with the use of Kerr rotation microscopy, consistent with the predictions of the spin Hall effect.
Abstract: Electrically induced electron-spin polarization near the edges of a semiconductor channel was detected and imaged with the use of Kerr rotation microscopy The polarization is out-of-plane and has opposite sign for the two edges, consistent with the predictions of the spin Hall effect Measurements of unstrained gallium arsenide and strained indium gallium arsenide samples reveal that strain modifies spin accumulation at zero magnetic field A weak dependence on crystal orientation for the strained samples suggests that the mechanism is the extrinsic spin Hall effect
1,999 citations