Resonant inversion of the circular photogalvanic effect in<i>n</i>-doped quantum wells

Ganichev, Sergey; Belkov, Vassilij; Schneider, Petra; Ivchenko, E. L.; Tarasenko, S. A.; Wegscheider, Werner; Weiss, Dieter; Schuh, Dieter; Beregulin, E.; Prettl, Wilhelm

doi:10.1103/physrevb.68.035319

Cited by 75 publications

(114 citation statements)

References 15 publications

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“…The injection of spin-polarized electric current in QWs due to intersubband transitions caused by circularly polarized radiation has already been observed by Ganichev et al 11 . In contrast, here we investigate a pure spin current, where electrons moving in opposite directions have opposite orientations of spins, not accompanied by a net electrical current.…”

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confidence: 63%

Spin current injection by intersubband transitions in quantum wells

Sherman

Najmaie

Sipe

2005

Applied Physics Letters

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We show that a pure spin current can be injected in quantum wells by the absorption of linearly polarized infrared radiation, leading to transitions between subbands. The magnitude and the direction of the spin current depend on the Dresselhaus and Rashba spin-orbit coupling constants and light frequency and, therefore, can be manipulated by changing the light frequency and/or applying an external bias across the quantum well. The injected spin current should be observable either as a voltage generated via the anomalous spin-Hall effect, or by spatially resolved pump-probe optical spectroscopy.Spin current is an interesting physical phenomenon in its own right, and could have application in the delivery and transfer of electron spins in spintronics devices. From a fundamental point of view, various issues raised in the theory of this effect are far from being satisfactorily settled. As was shown by Rashba 1 , a spin current exists even in the equilibrium state of a two-dimensional (2D) electron gas with spin-orbit (SO) coupling. The application of an external electric field has been suggested as a strategy for driving the system out of equilibrium and inducing a spin current exhibiting transport effects. Mal'shukov et al. 2 and Governale et al. 3 suggested applying a time-dependent bias across a semiconducting heterostructure, thus modulating the strength of the SO coupling and generating a spin current. Murakami et al. 4 and Sinova et al. 5 have shown that an in-plane electric field can cause a spin current, leading to the "intrinsic spin-Hall effect". Another possibility for the injection of spin current is coherently controlled optical excitations between the valence and the conduction band, as predicted by Bhat and Sipe 6,7 and observed experimentally in bulk crystals 8,9 and quantum wells (QWs) 10 .Here we show that a spin current can be injected in QWs by infrared (IR) light absorption, driving transitions between different subbands. The injection of spin-polarized electric current in QWs due to intersubband transitions caused by circularly polarized radiation has already been observed by Ganichev et al. 11 . In contrast, here we investigate a pure spin current, where electrons moving in opposite directions have opposite orientations of spins, not accompanied by a net electrical current. We show that the strength and direction of this pure spin current can be manipulated by modulating the SO coupling strength via applied bias 12 and/or adjusting the light frequency.As an example we consider the (011) GaAs QW, where the electron spins have a considerable out-of plane component, thus making possible the observation of the pure spin current by detecting the voltage generated via the anomalous spin-Hall effect 13,14 . The first two subbands in the well are typically separated by the energyhω 0 ≈ 100 meV; the exact value depends on the width of the QW, dopant concentration, and the boundary conditions. The SO Hamiltonian for the (011) QW, H SO = H D + H R , is the sum of a Dresselhaus term 15 , H D , originatin...

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confidence: 63%

Spin current injection by intersubband transitions in quantum wells

Sherman

Najmaie

Sipe

2005

Applied Physics Letters

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“…These measurements were particularly motivated by the search for the circular photogalvanic [14,68,69] and circular photon drag effects [70,71], i.e., photocurrents changing their direction upon switching of the radiation helicity [10,11,13], recently observed for Bi 2 Te 3 TI excited by near-infrared light [30]. Applying radiation at oblique incidence and measuring the photocurrent in the direction normal to the plane of incidence (yz), i.e., in the geometry for which circular photogalvanic [30,72,73] and circular photon drag effects [13,70] are expected, we detected a current which can be well fitted by J x = A x (f )(cos 4ϕ + 1)/2 (see Fig.…”

Section: Resultsmentioning

confidence: 99%

Photon drag effect in(Bi1−xSbx)2Te3three-dimensional topological insulators

et al. 2016

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We report on the observation of a terahertz radiation-induced photon drag effect in epitaxially grown nand p-type (Bi 1−x Sb x ) 2 Te 3 three-dimensional topological insulators with different antimony concentrations x varying from 0 to 1. We demonstrate that the excitation with polarized terahertz radiation results in a dc electric photocurrent. While at normal incidence a current arises due to the photogalvanic effect in the surface states, at oblique incidence it is outweighed by the trigonal photon drag effect. The developed microscopic model and theory show that the photon drag photocurrent can be generated in surface states. It arises due to the dynamical momentum alignment by time-and space-dependent radiation electric field and implies the radiation-induced asymmetric scattering in the electron momentum space. We show that the photon drag current may also be generated in the bulk. Both surface states and bulk photon drag currents behave identically upon variation of such macroscopic parameters as radiation polarization and photocurrent direction with respect to the radiation propagation. This fact complicates the assignment of the trigonal photon drag effect to a specific electronic system.

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“…In real QW structures, the spectral width of the intersubband resonance is substantially broadened. Allowance for the broadening can be made assuming, e.g., that the energy separation E 21 between the subbands varies in the QW plane [31,32]. Then, to the first order in the spin-orbit coupling, the spin current components in the subbands are given by…”

Section: Intersubband Transitions In N -Doped Qwsmentioning

confidence: 99%

Pure spin photocurrents

Ivchenko

Tarasenko

2008

Semicond. Sci. Technol.

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The pure spin currents, i.e., the counterflow of particles with opposite spin orientations, can be optically injected in semiconductors. Here, we develop a phenomenological theory, which describes the polarization dependencies of spin currents excited by linearly polarized light in bulk semiconductors and quantum well structures of various symmetries. We present microscopic descriptions of the pure spin photocurrents for interband optical transitions in undoped quantum wells as well as for direct intersubband and indirect intrasubband (Drude-like) transitions in n-doped quantum well structures. We also demonstrate that pure spin currents can be generated in structures of sufficiently low symmetries by simple electron gas heating. The theoretical results are compared with recent experimental observations.

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Resonant inversion of the circular photogalvanic effect inn-doped quantum wells

Cited by 75 publications

References 15 publications

Spin current injection by intersubband transitions in quantum wells

Spin current injection by intersubband transitions in quantum wells

Photon drag effect in(Bi1−xSbx)2Te3three-dimensional topological insulators

Pure spin photocurrents

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