Optical spin resonance and transverse spin relaxation in magnetic semiconductor quantum wells

Crooker, S. A.; Awschalom, D. D.; Baumberg, Jeremy J.; Flack, F.; Samarth, N.

doi:10.1103/physrevb.56.7574

Cited by 322 publications

(262 citation statements)

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“…84 Spin relaxation has also been investigated in In/GaAs (Paillard et al, 2001;Cortez et al, 2002), in an InAs/ GaSb superlattice , in InGaAs (Guettler et al, 1998), in GaAsSb multiple quantum wells . II-VI quantum wells, specifically ZnCdSe, were studied by Kikkawa et al (1997), who found s Ϸ1 ns, weakly dependent on both mobility and temperature, in the range 5ϽTϽ270 K. Electron and hole spin dephasing have also been investigated in dilute magnetic semiconductor quantum wells doped with Mn ions (Crooker et al, 1997;Camilleri et al, 2001).…”

Section: Low-dimensional Semiconductor Structuresmentioning

confidence: 99%

Spintronics: Fundamentals and applications

2004

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Spintronics, or spin electronics, involves the study of active control and manipulation of spin degrees of freedom in solid-state systems. This article reviews the current status of this subject, including both recent advances and well-established results. The primary focus is on the basic physical principles underlying the generation of carrier spin polarization, spin dynamics, and spin-polarized transport in semiconductors and metals. Spin transport differs from charge transport in that spin is a nonconserved quantity in solids due to spin-orbit and hyperfine coupling. The authors discuss in detail spin decoherence mechanisms in metals and semiconductors. Various theories of spin injection and spin-polarized transport are applied to hybrid structures relevant to spin-based devices and fundamental studies of materials properties. Experimental work is reviewed with the emphasis on projected applications, in which external electric and magnetic fields and illumination by light will be used to control spin and charge dynamics to create new functionalities not feasible or ineffective with conventional electronics. CONTENTS

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Section: Low-dimensional Semiconductor Structuresmentioning

confidence: 99%

Spintronics: Fundamentals and applications

2004

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“…For the GaAs (100) surface we observe an increase from about 60 ps to 1600 ps over an energy range of more than 0.3 eV, whereas the spin-relaxation time for the (011) surface is about 60 ps, independent of energy. The bulk spin relaxation was measured on an identical sample by means of the time-resolved magnetooptical Faraday effect [16,17]. The bulk spin-relaxation time was found to be 60 ps at room temperature regardless of the crystal orientation and is also shown in Figure 4 as a guide to the eye.…”

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confidence: 99%

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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“…We attribute this to the spin relaxation of the photoexcited holes, which lose their initial spin orientation very fast. 21 Here we don't consider this fast decay, i.e., hole spin relaxation. Figure 2(a) shows TRKR traces under a magnetic field of 0.5 T at different temperatures of 4 K, 14 K, and 16 K. One can find that the oscillatory envelope decay becomes much slower from 4 K to 14 K, and a little faster from 14 K to 16 K [see the inset of Fig.…”

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Effect of electron-electron scattering on spin dephasing in a high-mobility low-density two-dimensional electron gas

Ruan

Luo

et al. 2008

Phys. Rev. B

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Utilizing time-resolved Kerr rotation techniques, we have investigated the spin dynamics of a high mobility, low density two dimensional electron gas in a GaAs/Al 0.35 Ga 0.65 As heterostructure in dependence on temperature from 1.5 K to 30 K. It is found that the spin relaxation/dephasing time under a magnetic field of 0.5 T exhibits a maximum of 3.12 ns around 14 K, superimposed on an increasing background with rising temperature. The appearance of the maximum is ascribed to that at the temperature where the crossover from the degenerate to the nondegenerate regime takes place, electron-electron Coulomb scattering becomes strongest, and thus inhomogeneous precession broadening due to D'yakonov-Perel' (DP) mechanism becomes weakest. These results agree with the recent theoretical predictions [Zhou et al., PRB 75, 045305 (2007)], verifying the importance of electron-electron Coulomb scattering to electron spin relaxation/dephasing. PACS numbers: 72.25.Rb, 71.70.Ej, 78.47.jc In recent years, spin dynamics in semiconductors has attracted considerable attention because of its potential application in the spin-based devices. 1 The operation of these devices requires spin lifetime long enough to achieve storage, transport and processing of information. Therefore, a comprehensive understanding of spin relaxation mechanism is a key factor for the realization of these devices. It is generally accepted that the D'yakonov-Perel' (DP) mechanism is the leading spin relaxation/dephasing (R/D) mechanism in n-type zincblende semiconductors. 2 This is caused by an wavevector kdependent effective magnetic field Ω(k) from the bulk inversion asymmetry, 3 i.e., the Dresselhaus term, and/or the structure inversion asymmetry, 4 i.e., the Rashba term. The spin relaxation rate can be determined by τ −1 = Ω(k) 2 τ P (k), where τ P (k) is the momentum relaxation time. 5 As the electronelectron Coulomb scattering does not contribute to the momentum relaxation time τ p , it has long been widely believed that the electron-electron Coulomb scattering is irrelevant in the spin relaxation. 5,6,7,8,9,10,11 However, it was first pointed out by Wu and Ning 12 that in the presence of inhomogeneous broadening, any scattering, including the spin conserving electron-electron Coulomb scattering, can cause an irreversible spin relaxation and dephasing. This inhomogeneous broadening can be the energy-dependent g-factor, 12 the DP term, 13,14 and even the k-dependent spin diffusion along a spacial gradient. 15 In n-type GaAs quantum well, the importance of the electron-electron scattering to the spin relaxation was proved by Glazov and Ivchenko 16 by using perturbation theory and Weng and Wu 14 from a fully microscopic many-body approach. In a temperature-dependent experimental study of the spin relaxation in n-type (001) quantum wells, Harleyet al. indirectly verified the effects of the electron-electron scattering on spin relaxation. 17,18 Nevertheless, the importance of the Coulomb scattering to the spin relaxation/dephasing (R/D)has not yet been ...

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Optical spin resonance and transverse spin relaxation in magnetic semiconductor quantum wells

Cited by 322 publications

References 40 publications

Spintronics: Fundamentals and applications

Spintronics: Fundamentals and applications

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

Effect of electron-electron scattering on spin dephasing in a high-mobility low-density two-dimensional electron gas

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