Spatially Resolved Spin-Injection Probability for Gallium Arsenide

LaBella, V. P.; Bullock, D. W.; Ding, Zhao; Venkatesan, A.; Oliver, W. F.; Salamo, Gregory J.; Thibado, P. M.; Mortazavi, Mansour

doi:10.1126/science.292.5521.1518

Cited by 98 publications

(46 citation statements)

References 28 publications

(38 reference statements)

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“…054. Progress in ''spintronics'' is made by the recent demonstrations of the injection of a spin-polarized current from both ferromagnetic metals [8][9][10][11] and magnetic semiconductors 12,13 into a semiconductor.…”

Section: Introductionmentioning

confidence: 99%

Theory of ferromagnetism in planar heterostructures of (Mn,III)-V semiconductors

Fernández-Rossier

Sham

2001

Phys. Rev. B

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A density-functional theory of ferromagnetism in heterostructures of compound semiconductors doped with magnetic impurities is presented. The variable functions in the density-functional theory are the charge and spin densities of the itinerant carriers and the charge and localized spins of the impurities. The theory is applied to study the Curie temperature of planar heterostructures of III-V semiconductors doped with manganese atoms. The mean-field, virtual-crystal and effective-mass approximations are adopted to calculate the electronic structure, including the spin-orbit interaction, and the magnetic susceptibilities, leading to the Curie temperature. By means of these results, we attempt to understand the observed dependence of the Curie temperature of planar ␦-doped ferromagnetic structures on variation of their properties. We predict a large increase of the Curie temperature by additional confinement of the holes in a ␦-doped layer of Mn by a quantum well.

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Section: Introductionmentioning

confidence: 99%

Theory of ferromagnetism in planar heterostructures of (Mn,III)-V semiconductors

Fernández-Rossier

Sham

2001

Phys. Rev. B

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“…Tunnelling-induced luminescence microscopy is another example of a technique that has revealed the characteristics of the injection of spin-polarized electrons, using a ferromagnetic metallic tip of a scanning tunnelling microscope to inject into a non-ferromagnetic semiconductor 8 . However, this is a surface-sensitive technique that cannot probe the polarization of injected electrons from a buried interface in an operational device.…”

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confidence: 99%

Direct measurement of the electronic spin diffusion length in a fully functional organic spin valve by low-energy muon spin rotation

et al. 2008

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Electronic devices that use the spin degree of freedom hold unique prospects for future technology. The performance of these 'spintronic' devices relies heavily on the efficient transfer of spin polarization across different layers and interfaces. This complex transfer process depends on individual material properties and also, most importantly, on the structural and electronic properties of the interfaces between the different materials and defects that are common to real devices. Knowledge of these factors is especially important for the relatively new field of organic spintronics, where there is a severe lack of suitable experimental techniques that can yield depth-resolved information about the spin polarization of charge carriers within buried layers of real devices. Here, we present a new depth-resolved technique for measuring the spin polarization of current-injected electrons in an organic spin valve and find the temperature dependence of the measured spin diffusion length is correlated with the device magnetoresistance.R ecently great efforts have been undertaken to use the spin degree of freedom in electronic devices. These activities are fuelled by the potential prospects of spin-electronic (or 'spintronic') devices for example in terms of increased processing speed and integration, non-volatility, reduced power consumption, multifunctionality and their suitability for quantum computing 1 . The most common method for using the spin in devices is based on the alignment of the electron spin ('up' or 'down') relative to either a reference magnetic field or the magnetization orientation of a ferromagnetic layer. Device operation normally proceeds with measuring a quantity such as the electrical current that depends on how the degree of spin alignment is transferred across the device. The so-called 'spin valve' is a prominent example of such a spin-enabled device that has already revolutionized hard-drive read heads and magnetic memory 1 . The efficient transfer of spin polarization in real device structures remains one of the most difficult challenges in spintronics, because it is dependent on more than just the properties of the individual materials that comprise the device.Recently 2,3 , the use of organic materials in spintronics has become of significant interest, primarily owing to their ease and small cost of processing and electronic and structural flexibility. Furthermore, the extremely long spin coherence times found in organic materials offer considerable advantages over other materials 3 . This favourable property is related to two factors, first the weak spin-orbit coupling of light elements such as carbon and second to the small nuclear hyperfine interaction 4,5 . The latter arises because the electron transport in π-conjugated molecules is normally confined to molecular states, delocalized to the carbon rings, the predominant isotope of which, 12 C, has zero nuclear spin 4 .A common way to measure spin diffusion is based on time-resolved optical techniques, where spin-polarized charge carrie...

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“…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.…”

mentioning

confidence: 99%

mentioning

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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Spatially Resolved Spin-Injection Probability for Gallium Arsenide

Cited by 98 publications

References 28 publications

Theory of ferromagnetism in planar heterostructures of (Mn,III)-V semiconductors

Theory of ferromagnetism in planar heterostructures of (Mn,III)-V semiconductors

Direct measurement of the electronic spin diffusion length in a fully functional organic spin valve by low-energy muon spin rotation

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

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