Spin Relaxation under Optical Orientation in Semiconductors

Pikus, G. E.; Titkov, A. N.

doi:10.1016/b978-0-444-86741-4.50008-1

Cited by 177 publications

(332 citation statements)

References 13 publications

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“…Surprisingly, the spin splitting is more of a BIA-type rather than an SIA-type, contradicting the conventional knowledge that an SIA-type term described by H 2 is responsible for spin splitting in strained semiconductors [23,25,26,27,28,29]. Theoretically, the Dresselhaus term H 1 is a bulkinversion asymmetry term that appears even in the absence of strain.…”

Section: Fig 1: Direction Of the Internal Magnetic Fieldcontrasting

confidence: 42%

“…The term H 2 is a structural inversion asymmetry (SIA)-type term that has its origin in the acoustic phonon interaction of the valence band with the conduction band [23]. In the framework of the Kane's 8 × 8 matrix (2 × 2 for the conduction and split-off band and 4 × 4 for the valence band) the conduction band couples to the valence band.…”

Section: Fig 1: Direction Of the Internal Magnetic Fieldmentioning

confidence: 99%

“…By group theory, inversion symmetry breaking bulk strained semiconductors exhibit three main types of spin splitting [23]:…”

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confidence: 99%

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Spin splitting and spin current in strained bulk semiconductors

Bernevig

Zhang

2005

Phys. Rev. B

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We present a theory for two recent experiments in bulk strained semiconductors [1,2] and show that a new, previously overlooked, strain spin-orbit coupling term may play a fundamental role. We propose simple experiments that could clarify the origin of strain-induced spin-orbit coupling terms in inversion asymmetric semiconductors. We predict that a uniform magnetization parallel to the electric field will be induced in the samples studied in [1,2] for specific directions of the applied electric field. We also propose special geometries to detect spin currents in strained semiconductors. 72.15. Gd Spin manipulation in semiconductors has seen remarkable theoretical and experimental interest in recent years with the advent of spin-electronics and with the realization that strong spin-orbit coupling in certain materials can influence the transport of carriers in so-called spintronics devices [3]. In particular, the issue of creating spin polarization of carriers in nonmagnetic semiconductors with spin-orbit coupling using only electric fields has caused a flurry of theoretical and experimental activity [4,5,6,7,8,9,10,11,12,13,14,15,16]. Two kinds of theories of spin-polarization under the action of an electric field have been put forward. The first kind, dating back since the mid 1980's [9], predicts the existence of a spatially homogeneous net spin polarization perpendicular to the applied electric current in two dimensional samples with spin-orbit interaction. This effect is dissipative and has been recently observed experimentally [17]. There also exist two very recent [4,5] theories predicting non-dissipative, intrinsic spin currents with the spin polarization and flow direction perpendicular to each other and to the electric field. This effect does not create a bulk magnetization but, if observed, can be used for spin injection, and its validity is being experimentally tested at the present time. One of the theories [5] predicts a spin current polarized out of plane and flowing perpendicular to the in-plane electric field applied on a 2-dimensional semiconductor sample exhibiting Rashba spin-orbit coupling. As long as the Rashba spin splitting is large enough, the spin conductivity is 'universal' (e/8π ) in the sense that it does not depend on the value of the coupling. The other effect [4] appears in the valence band of the bulk samples and is proportional to the spin-orbit splitting of the valence bands (to the difference between the Fermi momenta of the heavy and light-hole bands).In the first part of this letter we analyze the theory behind two recent experiments in bulk strained semiconductors [1,2] where an electric-field-induced uniform homogeneous spin polarization upon an applied electric field is observed. We make the case that the observed spinsplitting (whose origin is puzzling) and spin polarization is due to a previously overlooked strain-spin-splitting term, and propose easy experimental checks of our theory.In the second part of this letter we predict the appearance of an intrinsic spin po...

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Section: Fig 1: Direction Of the Internal Magnetic Fieldcontrasting

confidence: 42%

Section: Fig 1: Direction Of the Internal Magnetic Fieldmentioning

confidence: 99%

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Spin splitting and spin current in strained bulk semiconductors

Bernevig

Zhang

2005

Phys. Rev. B

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“…In bulk GaAs, the relaxation of optically induced spin polarizations has been studied intensely for more than 30 years. Early work has led to the identification of several mechanisms that destroy the spin polarization, and good agreement between experiment and theory was found on the level of numerical and experimental accuracy available at that time [3]. In recent years, there has been renewed experimental and theoretical interest in spin relaxation, with many experimental studies focusing on undoped and n-doped semiconductors [4,5].…”

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confidence: 99%

“…To clarify this point we theoretically investigate the spin-relaxation time due to the BAP mechanism [3], which is expected to dominate in the present temperature and doping density range [18]. The original analysis [13] introduced an explicitly momentum dependent spin decay rate 1/(2τ s BAP ) in Born approximation that describes the spin-dependent population relaxation…”

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Energy-resolved electron spin dynamics at surfaces ofp-doped GaAs

et al. 2006

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Electron-spin relaxation at different surfaces of p-doped GaAs is investigated by means of spin, time and energy resolved 2-photon photoemission. These results are contrasted with bulk results obtained by time-resolved Faraday rotation measurements as well as calculations of the Bir-Aronov-Pikus spin-flip mechanism. Due to the reduced hole density in the band bending region at the (100) surface the spin-relaxation time increases over two orders of magnitude towards lower energies. At the flat-band (011) surface a constant spin relaxation time in agreement with our measurements and calculations for bulk GaAs is obtained. PACS numbers: 72.25.Mk,72.25.Rb,78.47.+p In recent years, much experimental and theoretical work has been focused on the control and manipulation of the electronic spin degree of freedom independently of its charge, with the ultimate goal of spintronics devices, in which the electron spins are the carriers of the information [1]. The limiting factor for the usefulness of the information encoded in a spin-polarized current in a non-ferromagnetic semiconductor is the relaxation of the spin polarization, which is caused by a variety of interaction mechanisms [2]. In bulk GaAs, the relaxation of optically induced spin polarizations has been studied intensely for more than 30 years. Early work has led to the identification of several mechanisms that destroy the spin polarization, and good agreement between experiment and theory was found on the level of numerical and experimental accuracy available at that time [3]. In recent years, there has been renewed experimental and theoretical interest in spin relaxation, with many experimental studies focusing on undoped and n-doped semiconductors [4,5]. Early results for p-doped GaAs were obtained by means of hot photon luminescence and the Hanle effect [6]. Surfaces and interfaces, such as Schottky barriers, originally received comparatively little attention [7,8]. More recently, however, interfaces have been studied because of their importance for spintronics device applications where efficient electrical spin injection from a ferromagnetic metal or half-metal through a Schottky barrier into the semiconductor is of utmost importance [9]. The difficulty of efficient spin injection has stimulated interest in a fundamental understanding of spin-flip scattering at semiconductor surfaces and interfaces, e. g., at step edges [10].The purpose of this paper is the investigation of electron spin-relaxation in p-doped GaAs and the unambiguous identification of surface effects on the electron spin-relaxation. Using a spin, energy and time-resolved photoemission technique [11] we study the room-temperature spin-dependent electron dynamics at two surfaces with different characteristics [12]: the (100) surface with pronounced band-bending and the cleaved (011) surface, for which we expect flat-band conditions. To obtain a complete picture of the spin relaxation at surfaces as compared to the bulk we have also measured bulk spin relaxation-times by time-resolved Farada...

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Suppression of Dyakonov-Perel Spin Relaxation in 2D Channels of Finite Width

Kiselev

2000

phys. stat. sol. (b)

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Spin Relaxation under Optical Orientation in Semiconductors

Cited by 177 publications

References 13 publications

Spin splitting and spin current in strained bulk semiconductors

Spin splitting and spin current in strained bulk semiconductors

Energy-resolved electron spin dynamics at surfaces ofp-doped GaAs

Suppression of Dyakonov-Perel Spin Relaxation in 2D Channels of Finite Width

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