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Engels, G.; Lange, James N.; Schäpers, Th.; Lüth, H.

doi:10.1103/physrevb.55.r1958

Cited by 555 publications

(431 citation statements)

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“…Heterostructures in which the 2DEG is formed by an asymmetric confining potential also exhibit the Rashba spin-orbit interaction 11 . As shown experimentally, the Rashba coupling strength can be tuned via proper gating of the structure 12,13 , which makes the Rashba interaction very appealing for potential technological applications involving spin control. More recently, yet a new type of spin-orbit interaction has been found in symmetric two-dimensional quantum structures with two subbands: the inter-subbandinduced spin-orbit coupling 14,15 .…”

Section: Introductionmentioning

confidence: 99%

Energy spectra for quantum wires and two-dimensional electron gases in magnetic fields with Rashba and Dresselhaus spin-orbit interactions

2010

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We introduce an analytical approximation scheme to diagonalize parabolically confined two dimensional electron systems with both the Rashba and Dresselhaus spin-orbit interactions. The starting point of our perturbative expansion is a zeroth-order Hamiltonian for an electron confined in a quantum wire with an effective spin-orbit induced magnetic field along the wire, obtained by properly rotating the usual spin-orbit Hamiltonian. We find that the spin-orbit-related transverse coupling terms can be recast into two parts W and V , which couple crossing and non-crossing adjacent transverse modes, respectively. Interestingly, the zeroth-order Hamiltonian together with W can be solved exactly, as it maps onto the Jaynes-Cummings model of quantum optics. We treat the V coupling by performing a Schrieffer-Wolff transformation. This allows us to obtain an effective Hamiltonian to third order in the coupling strength kRℓ of V , which can be straightforwardly diagonalized via an additional unitary transformation. We also apply our approach to other types of effective parabolic confinement, e.g., 2D electrons in a perpendicular magnetic field. To demonstrate the usefulness of our approximate eigensolutions, we obtain analytical expressions for the n th Landau-level gn-factors in the presence of both Rashba and Dresselhaus couplings. For small values of the bulk g-factors, we find that spin-orbit effects cancel out entirely for particular values of the spin-orbit couplings. By solving simple transcendental equations we also obtain the band minima of a Rashba-coupled quantum wire as a function of an external magnetic field. These can be used to describe Shubnikov-de Haas oscillations. This procedure makes it easier to extract the strength of the spin-orbit interaction in these systems via proper fitting of the data.

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Section: Introductionmentioning

confidence: 99%

Energy spectra for quantum wires and two-dimensional electron gases in magnetic fields with Rashba and Dresselhaus spin-orbit interactions

2010

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“…The gatetunable [2] Rashba s-o interaction [3] present in two-dimensional electron gases (2DEGs) formed in structurally asymmetric confining potentials offers such a possibility. The seminal proposal of Datta and Das [4] of a spin field effect transistor highlights the use of the Rashba spin-orbit interaction to coherently rotate spins.…”

Section: Introductionmentioning

confidence: 99%

Spin orbit interaction and zitterbewegung in symmetric wells

Bernardes

Schliemann

Egues

et al. 2006

Phys. Status Solidi (c)

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Recently, we have introduced a novel inter-subband-induced spin-orbit (s-o) coupling [Phys. Rev. Lett. 99, 076603 (2007); cond-mat/0607218] arising in symmetric wells with at least two subbands. This new s-o coupling gives rise to an usual zitterbewegung -i.e. the semiconductor analog to the relativistic trembling motion of electrons -with cycloidal motion without magnetic fields. Here we complement these findings by explicitly deriving expressions for the corresponding zitterbewegung in spin space.

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“…5 shows the replot of the polarization as a function of L m , which indicates that finite polarization remains as long as L m exceeds the system length. The electron mean free path in the InGaAs 2DES channel exceeds 1µm in the wide range of the gate voltage, 4 and the spin filtering effect by nonuniform SOI strength is expected to survive in actually fabricated devices. We have also changed the distribution of the impurities to the binary distribution, where the site energy W i takes only two values, 0 and W > 0.…”

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confidence: 99%

“…1,2 To control the spin of electrons in semiconductors, the spin-orbit interaction (SOI) due to the lack of the inversion symmetry in two dimensional electron system (2DES) is quite useful since its strength can be controlled by an additional gate voltage. 3,4 The spin field-effect transistor proposed by Datta and Das is a hybrid structure of ferromagnetic electrodes (FM) and a semiconductor (SM) 2DES channel. 5 This hybrid device, however, requires a complex and careful fabrication process.…”

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confidence: 99%

Mesoscopic Stern-Gerlach spin filter by nonuniform spin-orbit interaction

et al. 2005

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A novel spin filtering in two-dimensional electron system with nonuniform spin-orbit interactions (SOI) is theoretically studied. The strength of SOI is modulated perpendicular to the charge current. A spatial gradient of effective magnetic field due to the nonuniform SOI causes the Stern-Gerlach type spin separation. The direction of the polarization is perpendicular to the current and parallel to the spatial gradient. Almost 100 % spin polarization can be realized even without applying any external magnetic fields and without attaching ferromagnetic contacts. The spin polarization persists even in the presence of randomness.Considerable attention has been devoted to the manipulation of the electron spin in semiconductor systems. 1,2 To control the spin of electrons in semiconductors, the spin-orbit interaction (SOI) due to the lack of the inversion symmetry in two dimensional electron system (2DES) is quite useful since its strength can be controlled by an additional gate voltage. 3,4 The spin field-effect transistor proposed by Datta and Das is a hybrid structure of ferromagnetic electrodes (FM) and a semiconductor (SM) 2DES channel. 5 This hybrid device, however, requires a complex and careful fabrication process. Furthermore, spin injection efficiency from FM into SM is poor because of a conductance mismatch between FM and SM. 6 Therefore, it is desired that spin polarized carriers in semiconductor channels can be generated and manipulated without attaching any ferromagnetic contacts and without applying any external magnetic fields. Several devices based on the SOI are proposed to have spin polarized carriers in semiconductor channel. 7,8,9,10,11,12,13 From experimental point of view, the spin polarization mechanism should be robust against disorder.One of the historical experiments of the spin separation is the Stern-Gerlach experiment. 14 They have considered a particle with spin propagating through the nonuniform magnetic field. Because the derivative of the magnetic field plays a role of the spin-dependent potential, particles with up and down spins are accelerated in opposite directions. However, for electrons, this effect is hard to observe because of the effect of the Lorentz force acting on a electron beam in transverse directions. 15 The importance of the modulated SOI on the transport properties has recently been stressed. 16,17,18,19,20 Since the effect of SOI on the propagating electrons is, in some respect, similar to the effective magnetic field, the modulated SOI is expected to cause the Stern-Gerlach like spin separation. In this paper, we theoretically demonstrate that a mesoscopic Stern-Gerlach spin filter is feasible by using a nonuniform spin-orbit interaction as shown in Fig. 1. The strength of the SOI is modulated along the direction perpendicular to the charge current. We demonstrate that nearly 100% spin polarization (perpendicular both to the current and the direction normal to 2DES) can be achieved without a ferromagnetic contact and an external magnetic field. The above results a...

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Experimental and theoretical approach to spin splitting in modulation-dopedInxGa1

Cited by 555 publications

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Energy spectra for quantum wires and two-dimensional electron gases in magnetic fields with Rashba and Dresselhaus spin-orbit interactions

Energy spectra for quantum wires and two-dimensional electron gases in magnetic fields with Rashba and Dresselhaus spin-orbit interactions

Spin orbit interaction and zitterbewegung in symmetric wells

Mesoscopic Stern-Gerlach spin filter by nonuniform spin-orbit interaction

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