Electric current-induced spin orientation in quantum well structures

Ganichev, Sergey; Danilov, Sergey; Schneider, Petra; Belkov, Vassilij; Golub, L. E.; Wegscheider, Werner; Weiss, Dieter; Prettl, Wilhelm

doi:10.1016/j.jmmm.2005.10.048

Cited by 97 publications

(88 citation statements)

References 13 publications

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“…The generation of a current from a non-equilibrium spin polarization goes under the equivalent names of spin galvanic effect (SGE) or inverse Edelstein effect (IEE), while the reciprocal phenomenon of current-induced spin polarizations is referred to as inverse spin galvanic effect (ISGE) or Edelstein effect (EE). The first experimental observation of the SGE/IEE was in quantum wells, by measuring the current produced by the absorption of polarized light [10][11][12]. More recently it has been shown that a non-equilibrium spin polarization injected by spin-pumping into an Ag|Bi [13] or Fe|GaAs [14] interface also yields an electrical current.…”

Section: Introductionmentioning

confidence: 99%

Theory of current-induced spin polarization in an electron gas

et al. 2017

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We derive the Bloch equations for the spin dynamics of a two-dimensional electron gas in the presence of spin-orbit coupling. For the latter we consider both the intrinsic mechanisms of structure inversion asymmetry (Rashba) and bulk inversion asymmetry (Dresselhaus), and the extrinsic ones arising from the scattering from impurities. The derivation is based on the SU(2) gauge-field formulation of the Rashba-Dresselhaus spin-orbit coupling. Our main result is the identification of a spin-generation torque arising from Elliot-Yafet scattering, which opposes a similar term arising from Dyakonov-Perel relaxation. Such a torque, which to the best of our knowledge has gone unnoticed so far, is of basic nature, i. e. should be effective whenever Elliott-Yafet processes are present in a system with intrinsic spin-orbit coupling, irrespective of further specific details. The spin-generation torque contributes to the current-induced spin polarization (CISP), also known as inverse spin-galvanic or Edelstein effect. As a result, the behavior of the CISP turns out to be more complex than one would surmise from consideration of the internal Rashba-Dresselhaus fields alone. In particular, the symmetry of the current-induced spin polarization does not necessarily coincide with that of the internal Rashba-Dresselhaus field, and an out-of-plane component of the CISP is generally predicted, as observed in recent experiments. We also discuss the extension to the three-dimensional electron gas, which may be relevant for the interpretation of experiments in thin films.

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Section: Introductionmentioning

confidence: 99%

Theory of current-induced spin polarization in an electron gas

et al. 2017

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“…The accumulation can be uniform 5,6 in the case of uniform Rashba spin-orbit coupling 7 or at the edges of a channel in either the Rashba model [8][9][10] or with spin-orbit coupling induced by lateral confinement. 11,12 Experiments have observed current induced spin polarization in n-type three-dimensional ͑3D͒ samples 13 and in two-dimensional ͑2D͒ hole systems 14,15 with spin polarization estimated to be up to 10%. 15 Further work suggests that a spin-polarized current can be produced in quantum wire junctions, 16,17 by a quantum point contact ͑QPC͒, 18,19 in a carbon nanotube, 20 in a ballistic ratchet, 21 in a torsional oscillator, 22 in vertical transport through a quantum well, 23 or in disordered mesoscopic systems.…”

Section: Introductionmentioning

confidence: 99%

Spin-polarized current generation from quantum dots without magnetic fields

Krich

Halperin

2008

Phys. Rev. B

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An unpolarized charge current passing through a chaotic quantum dot with spin-orbit coupling can produce a spin-polarized exit current without magnetic fields or ferromagnets. We use random matrix theory to estimate the typical spin polarization as a function of the number of channels in each lead in the limit of large spin-orbit coupling. We find rms spin polarizations up to 45% with one input channel and two output channels. Finite temperature and dephasing both suppress the effect, and we include dephasing effects using a variation of the third lead model. If there is only one channel in the output lead, no spin polarization can be produced, but we show that dephasing lifts this restriction.

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“…A related effect, in which the current is driven by the spin-flip process of the nonequilibrium population of electrons in the spin-split bands, is called the spingalvanic effect [6]. The most interesting consequence of the k-dependent spin splitting is the implication that an applied electric field would induce not only a charge current but also a spin polarization [7][8][9][10][11][12][13] along the direction perpendicular to the current.This Letter provides the experimental evidence of circularly polarized optical-excitation-induced spin photocurrent in (001) grown InGaAs=InAlAs 2DEGs under oblique incidence of radiation for interband excitation, which is 2 orders of magnitude stronger than similar observations using far-infrared excitation for intersubband transitions. The current-induced spin polarization in the same samples is measured using the Kerr rotation experiment.…”

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Spectral Dependence of Spin Photocurrent and Current-Induced Spin Polarization in anInGaAs/InAlAsTwo-Dimensional Electron Gas

et al. 2006

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The converse effects of spin photocurrent and current induced spin polarization are experimentally demonstrated in a two-dimensional electron gas system with Rashba spin splitting. Their consistency with the strength of the Rashba coupling as measured for the same system from beating of the Shubnikovde Haas oscillations reveals a unified picture for the spin photocurrent, current-induced spin-polarization, and spin-orbit coupling. In addition, the observed spectral inversion of the spin photocurrent indicates a system with dominating structure inversion asymmetry. DOI: 10.1103/PhysRevLett.96.186605 PACS numbers: 72.25.Fe, 72.25.Pn With the basic idea of the spin field effect transistor, as proposed by Datta and Das [1], the electric field tunable spin-orbit interaction has been an ideal candidate for manipulating the electron spin polarization. The structural inversion asymmetry (SIA) induced spin-orbit coupling (Rashba interaction [2]) in a two-dimensional electron gas (2DEG) system has attracted more and more attention due to its potential applications in spintronics devices. With spin splitting of the energy bands, optical excitation of quantum well (QW) structures by circularly polarized radiation will lead to a current whose direction and magnitude depend on the helicity of the incident light. This is named the circular photogalvanic effect (CPGE) and has been demonstrated using intersubband [3,4] or interband [5] excitations. A related effect, in which the current is driven by the spin-flip process of the nonequilibrium population of electrons in the spin-split bands, is called the spingalvanic effect [6]. The most interesting consequence of the k-dependent spin splitting is the implication that an applied electric field would induce not only a charge current but also a spin polarization [7][8][9][10][11][12][13] along the direction perpendicular to the current.This Letter provides the experimental evidence of circularly polarized optical-excitation-induced spin photocurrent in (001) grown InGaAs=InAlAs 2DEGs under oblique incidence of radiation for interband excitation, which is 2 orders of magnitude stronger than similar observations using far-infrared excitation for intersubband transitions. The current-induced spin polarization in the same samples is measured using the Kerr rotation experiment. These results are consistent with the spin splitting of the energy bands as examined by the beating of the Shubnikovde Haas (SdH) oscillations. The correlation in these experiments with great consistency reveals a unified picture for the spin photocurrent, current-induced spin-polarization and spin-orbit coupling. Furthermore, the theoretically predicted spectral inversion of the CPGE spin photocurrent is experimentally observed.Two samples (named D and E) studied here were In x Ga 1ÿx As=In 0:52 Al 0:48 As 2DEGs grown on a semiinsulating (001) InP substrate with well thickness of 14 nm. The SIA was achieved by doping of only one side of the barrier layer (on top of the well). To enhance the SIA, sample E wa...

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Electric current-induced spin orientation in quantum well structures

Cited by 97 publications

References 13 publications

Theory of current-induced spin polarization in an electron gas

Theory of current-induced spin polarization in an electron gas

Spin-polarized current generation from quantum dots without magnetic fields

Spectral Dependence of Spin Photocurrent and Current-Induced Spin Polarization in anInGaAs/InAlAsTwo-Dimensional Electron Gas

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