Electron spin manipulation using semimagnetic resonant tunneling diodes

Gruber, Th.; Keim, M.; Fiederling, R.; Reuscher, G.; Ossau, W.; Schmidt, G.; Molenkamp, L. W.; Waag, A.

doi:10.1063/1.1350600

Cited by 86 publications

(26 citation statements)

References 13 publications

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“…The experimental observation of resonant tunneling in semimagnetic (Zn,Mn)Se/BeTe double barrier structures were reported by Keim et al (Keim et al, 1999) although no spin splitting of subbands could be detected in electrical measurements. A suc- cessful efficient injection of spin-polarized current into GaAs using BeTe/ZnMnSe/BeTe RTDs were later demonstrated by the same group (Gruber et al, 2001). Clear evidence of spin splitting of the transmission resonance into two separate peaks was found in the IV-characteristics of ZnSe/BeZnSe/ZnMnSe/BeZnSe/ZnSe RTDs (Slobodskyy et al, 2003;Gould et al, 2004b).…”

Section: C3 Paramagnetic Spin-rtdsmentioning

confidence: 87%

Semiconductor spintronics

Fabian¹,

Matos-Abiague²,

Ertler³

et al. 2007

Acta Physica Slovaca. Reviews and Tutorials

922

1,204

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Spintronics refers commonly to phenomena in which the spin of electrons in a solid state environment plays the determining role. In a more narrow sense spintronics is an emerging research field of electronics: spintronics devices are based on a spin control of electronics, or on an electrical and optical control of spin or magnetism. While metal spintronics has already found its niche in the computer industry-giant magnetoresistance systems are used as hard disk read heads-semiconductor spintronics is yet to demonstrate its full potential. This review presents selected themes of semiconductor spintronics, introducing important concepts in spin transport, spin injection, Silsbee-Johnson spin-charge coupling, and spindependent tunneling, as well as spin relaxation and spin dynamics. The most fundamental spin-dependent interaction in nonmagnetic semiconductors is spin-orbit coupling. Depending on the crystal symmetries of the material, as well as on the structural properties of semiconductor based heterostructures, the spin-orbit coupling takes on different functional forms, giving a nice playground of effective spin-orbit Hamiltonians. The effective Hamiltonians for the most relevant classes of materials and heterostructures are derived here from realistic electronic band structure descriptions. Most semiconductor device systems are still theoretical concepts, waiting for experimental demonstrations. A review of selected proposed, and a few demonstrated devices is presented, with detailed description of two important classes: magnetic resonant tunnel structures and bipolar magnetic diodes and transistors. In view of the importance of ferromagnetic semiconductor materials, a brief discussion of diluted magnetic semiconductors is included. In most cases the presentation is of tutorial style, introducing the essential theoretical formalism at an accessible level, with case-study-like illustrations of actual experimental results, as well as with brief reviews of relevant recent achievements in the field. 72.25.Rb, 75.50.Pp, PACS

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Section: C3 Paramagnetic Spin-rtdsmentioning

confidence: 87%

Semiconductor spintronics

Fabian¹,

Matos-Abiague²,

Ertler³

et al. 2007

Acta Physica Slovaca. Reviews and Tutorials

922

1,204

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“…In this scheme, already proposed in the 70's by Aranov and Pikus [6], the spin polarized current is converted into circularly polarized electroluminescence; the degree of circular polarization of the electroluminescence of the spin-LED is directly proportional to the spin polarization of the carriers in the detection quantum well (QW). This approach has yielded evidence for spin injection using semi- [7] or ferro-magnetic [8] semiconductors, as well as ferromagnetic metal [9,10,11] contacts on GaAs based LEDs.Spin-LEDs are typically used in a top-emission measurement-geometry, where the external magnetic field is parallel to the current path, and parallel to the wave vector of the emitted light [7,9,10,12,13 ], as depicted in Fig. 1(a).…”

mentioning

confidence: 99%

Detection of electrical spin injection by light-emitting diodes in top- and side-emission configurations

Fiederling

Grabs

Ossau

et al. 2003

Applied Physics Letters

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Detection of the degree of circular polarization of the electroluminescence of a light-emitting diode fitted with a spin injecting contact (a spin-LED) allows for a direct determination of the spin polarization of the injected carriers. Here, we compare the detection efficiency of (Al,Ga)As spin-LEDs fitted with a (Zn,Be,Mn)Se spin injector in top-and side-emission configuration. In contrast with top emission, we cannot detect the electrical spin injection in side emission from analysing the degree of circular polarization of the electroluminescence. To reduce resonant optical pumping of quantum-well excitons in the side emission, we have analysed structures with mesa sizes as small as 1 µm.-2 -The efficient electrical injection and detection of a spin polarized current into semiconductor heterostructures is a key element for the development of semiconductor spintronics [1,2]. Originally, much effort was devoted to detecting magnetoresistance changes in ferromagnet / semiconductor / ferromagnet interfaces [3,4], where, because of the very small effects observed, it turned out to be difficult to find evidence for spin injection [5]. An important step forward could only be made when zincblende-based light-emitting diodes (LED) (e.g. in the (Al,Ga)As system) were used as detectors for electrical spin injection. In this scheme, already proposed in the 70's by Aranov and Pikus [6], the spin polarized current is converted into circularly polarized electroluminescence; the degree of circular polarization of the electroluminescence of the spin-LED is directly proportional to the spin polarization of the carriers in the detection quantum well (QW). This approach has yielded evidence for spin injection using semi- [7] or ferro-magnetic [8] semiconductors, as well as ferromagnetic metal [9,10,11] contacts on GaAs based LEDs.Spin-LEDs are typically used in a top-emission measurement-geometry, where the external magnetic field is parallel to the current path, and parallel to the wave vector of the emitted light [7,9,10,12,13 ], as depicted in Fig. 1(a).However, for ferromagnetic materials like (Ga,Mn)As where the magnetic moment of the manganese system is typically perpendicular to the growth axis, side-emitted electroluminescence has been used to infer the spin polarization [8]. In this geometry the magnetic field is also parallel to the wave vector of the emitted light, -3 -but at the same time perpendicular to the growth axis of the structure and the confinement axis of the QW (see Fig. 1(a)). This quasi-Voigt geometry gives rise to different selection rules for optical transitions in GaAs based QWs [14] compared with those applicable for top emission [15]. If the selection rules are strictly valid, they may prohibit the determination of electron spin polarization by circular polarized light. Recent work on (Ga,Mn)As based spin-LEDs reveals a remarkable influence of the measurement geometry on the observed spacer layer thickness dependence of the circular polarization of the electroluminescence [16].In view of this, it se...

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“…The doped Mn ions interact with the carriers through the sp-d exchange interaction, which results in the giant Zeeman splitting of the spin sublevels of the electron and hole. The spin-polarized current can be produced by the DMS-semiconductor heterostructures [5], or the resonant tunneling with the DMS as the potential well [6] due to the giant Zeeman splitting. Now the spin coherence relaxation time has reached ns level in the room temperature, and the coherence distance exceeds 100 μm.…”

Section: Rashba Wave Function One-dimensional Waveguide Boundary Comentioning

confidence: 99%

Rashba electron transport in one-dimensional quantum waveguides

Liu

Xia

Chang

2010

Sci. China Phys. Mech. Astron.

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The properties of Rashba wave function in the planar one-dimensional waveguide are studied, and the following results are obtained. Due to the Rashba effect, the plane waves of electron with the energy E divide into two kinds of waves with the wave vectors k 1 =k 0 +k δ and k 2 =k 0 −k δ , where k δ is proportional to the Rashba coefficient, and their spin orientations are +π/2 (spin up) and −π/2 (spin down) with respect to the circuit, respectively. If there is gate or ferromagnetic contact in the circuit, the Rashba wave function becomes standing wave form exp(±ik δ l)sin[k 0 (l−L)], where L is the position coordinate of the gate or contact. Unlike the electron without considering the spin, the phase of the Rashba plane or standing wave function depends on the direction angle θ of the circuit. The travel velocity of the Rashba waves with the wave vector k 1 or k 2 are the same ħk₀/m * . The boundary conditions of the Rashba wave functions at the intersection of circuits are given from the continuity of wave functions and the conservation of current density. Using the boundary conditions of Rashba wave functions we study the transmission and reflection probabilities of Rashba electron moving in several structures, and find the interference effects of the two Rashba waves with different wave vectors caused by ferromagnetic contact or the gate. Lastly we derive the general theory of multiple branches structure. The theory can be used to design various spin polarized devices. Rashba wave function, one-dimensional waveguide, boundary conditionThe physics of ballistic electron structures is governed by the elastic mean-free path, which can approach 100 μm in modulated-doped GaAs/AlGaAs hetero-junctions cooled to low temperatures. After an elastic collision the electron energy is unchanged and the phase memory is preserved. However, after an inelastic collision both energy and momentum change in an essentially random fashion and the phase information is lost. At low temperature, the phase coherence time is larger than the inelastic collision time.Some of the first observations of quantum interference were made using thin metal films and silicon inversion layers [1,2]. From then most of the quantum interferences and ballistic transports are observed in two-dimensional systems. The physics of the quantum interference includes: the Aharonov-Bohm effect, quantum interference transistors, universal conductance fluctuations, ballistic electron transport and Landauer-Büttiker formula, quantized conductance in point contacts, multi-terminal devices, quantum dot resonant tunneling devices, etc. In these structures the electron movement is dominated by the quantum mechanics, not the classical mechanics. In recent twenty years, mesoscopic physics and spintronics become two most active areas in condensed matter physics. Xia [3] considered that if the width of the structure is narrow enough compared to its length so that the transverse confinement energy is much larger than the longitudinal moving energy, then the electron movemen...

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Electron spin manipulation using semimagnetic resonant tunneling diodes

Cited by 86 publications

References 13 publications

Semiconductor spintronics

Semiconductor spintronics

Detection of electrical spin injection by light-emitting diodes in top- and side-emission configurations

Rashba electron transport in one-dimensional quantum waveguides

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