Spin-dependent transport of electrons in the presence of a smooth lateral potential and spin-orbit interaction

Govorov, Alexander O.; Kalameitsev, A. V.; Dulka, John

doi:10.1103/physrevb.70.245310

Cited by 21 publications

(24 citation statements)

References 18 publications

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“…[26][27][28] Since the eigenstates in the presence of the field b are spin polar-ized parallel to b, the adiabatic boundary implies a rotation of the spin polarization, S = e i z , where is the angle between the electron momentum and the normal of the interface. Before presenting our numerical results for the spin relaxation obtained by solving Eq.…”

Section: Spin Dynamics In Finite Systemsmentioning

confidence: 99%

Spin relaxation in narrow wires of a two-dimensional electron gas

et al. 2006

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How does an initially homogeneous spin polarization in a confined two-dimensional electron gas with Rashba spin-orbit coupling evolve in time? How does the relaxation time depend on system size? We study these questions for systems of a size that is much larger than the Fermi wavelength, but comparable and even shorter than the spin relaxation length. Depending on the confinement spin relaxation may become faster or slower than in the bulk. An initially homogeneously polarized spin system evolves into a spiral pattern.

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Section: Spin Dynamics In Finite Systemsmentioning

confidence: 99%

Spin relaxation in narrow wires of a two-dimensional electron gas

et al. 2006

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“…consists of the spin components for the initial state (see, e.g., [18,[22][23][24] for solid-state realizations). With the Hamiltonian in (3) invariant under rotations in the xy-plane, angular dependence in Eq.…”

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confidence: 99%

Measurement of noncommuting spin components using spin-orbit interaction

Sokolovski

Sherman

2011

Phys. Rev. A

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We propose a possible experiment aimed at a joint measurement of two non-commuting spin 1/2 components and analyze its physical meaning. We demonstrate that switching of a strong spinorbit interaction, e.g., in a solid state or a cold-atom system, for a short time interval simulates a simultaneous von Neumann measurement of the operators σx and σy. With the spin dynamics mapped onto the quantum coordinate-space motion, such an experiment determines averages of σx and σy over the duration of the measurement, however short the latter may be. These time averages, unlike the instantaneous values of σx and σy, may be evaluated simultaneously to an arbitrary accuracy.PACS numbers: 03.65. Ta,71.70.Ej Recent developments in quantum information and technology have brought the quantum measurement theory (QMT), originally formulated together with the principles of quantum mechanics (see, e.g. [1]) into the research focus. Continuing progress in experimental techniques has made it possible to test the QMT as well as make new, sometimes surprising, predictions [2]. One fundamental problem in the QMT is that of joint measurement of non-commuting variables which, according to the uncertainty principle, cannot have well-defined values simultaneously. An operational approach to the joint measurement of particle's position and momentum was proposed in the pioneering work of Arthurs and Kelly [3][4][5]. Recent attempts to extend it to non-commuting spin components can be found in Refs. [6][7][8]. Still, important questions concerning the exact nature of the measured quantity, the accuracy to which its value can be determined, and the back-action a exerted on the measured system remain unanswered to this day. The purpose of this Letter is to answer these questions, crucial for understanding the nature of any quantum measurement. We also suggest an optimal experimental technique for simulating a joint von Neumann measurement on a generic spin-1/2 system, of interest in quantum information. For the latter we propose the use of modern techniques developed for controlling spin-orbit (SO) interactions in solids [9,10] and for cold atoms in optical lattices [11][12][13][14]. The key feature of such systems, currently attracting interest for both fundamental and applied reasons (for a review see [10]), is entanglement between the translational and the spin (pseudospin) degrees of freedom. Generated once the SO coupling is switched on, the entanglement allows the particle play the role of a von Neumann pointer. Modulation of the SO coupling strength, including switching it on and off on demand, can be achieved for electrons in semiconductor structures by applying external bias to the metallic gates attached to the system [9,10]. For cold atoms similar effect can be realized with specially designed optical fields [11][12][13][14]. With the above in mind, for a particle of mass M , we will consider one of the following Hamiltonians ( = 1):wherep x andp y are the components of two-dimensional momentum,p 2 ≡p 2 x +p 2 y and the indices of t...

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“…We point out that the SOI due to in-plane potential gradient has largely been neglected even though there have been studies on scattering by microstructures in SOI twodimensional electron gas ͑2DEG͒. [17][18][19][20][21] An exception is a study on a smooth lateral potential. 17 It is then of interest to invoke the in-plane potential gradient SOI, to propose a relevant local in-plane potential pattern, and to study their resonant interplay.…”

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confidence: 99%

Resonant spin dipole induced by an in-plane potential gradient spin-orbit interaction

2007

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Spin-orbit interaction ͑SOI͒ arising from in-plane potential gradient is invoked for the generation of spin accumulation in a driven electric field. The SOI and a local in-plane potential pattern together bring about resonant spin dependent scatterings to electrons in a nonequilibrium distribution. In the vicinity of a ringshaped potential barrier pattern, a spin dipole distribution with a resonant dipole strength characteristic is obtained. As the chemical potential is increased across one such resonant energy, the dipole strength manifests both sign reversal and large amplitude enhancement. The scattering resonance, thus, provides an additional knob for the manipulation of the spin accumulation.Spintronics exploits electron spin as the key physical entity for a new paradigm upon which novel device concepts and applications can be contrived. 1,2 The recent intensive studies on spin-Hall effect, where an external electric field leads to spin flow in the transverse direction, spin accumulation at lateral edges, and spin polarization in the bulk, 3-14 demonstrate great interest in nonmagnetic generation of spin transport and accumulation in semiconductors.The spin-orbit coupling is much larger in semiconductors than in vacuum by a factor of, typically, 6 orders of magnitude. This factor is the ratio of the Dirac gap ͑m 0 c 2 = 0.5 MeV͒ in vacuum and an effective Dirac gap ͑E g ϳ 1 eV͒ in semiconductor. 15,16 Various spin-orbit interactions ͑SOIs͒ have been considered. Of intrinsic nature are the Rashba 4,7,9-13 and Dresselhaus SOIs, 6,11 and of extrinsic nature is the impurity-induced SOI. 3,5,8,10,13 The Rashba SOI originates from a structure inversion asymmetry-the asymmetry in the confinement potential normal to a quantum well ͑QW͒. The Dresselhaus SOI originates from the inversion asymmetry in the crystal potential. The impurity-induced SOI is the atomiclike SOI albeit occurring in a semiconductor host. We point out that the SOI due to in-plane potential gradient has largely been neglected even though there have been studies on scattering by microstructures in SOI twodimensional electron gas ͑2DEG͒. 17-21 An exception is a study on a smooth lateral potential. 17 It is then of interest to invoke the in-plane potential gradient SOI, to propose a relevant local in-plane potential pattern, and to study their resonant interplay. Very recently, strong in-plane gradient of the crystal potential in the surface layer of Bi/ Ag͑111͒ alloy is identified as the major physics behind a giant spin splitting. 22 Thus, the physics we explore here could also be of relevance to surface spintronics in metallic alloys.Of our major concern here is the in-plane potential gradient SOI from a ring-shaped potential barrier ͑RSPB͒ in a symmetric QW, as shown in Fig. 1. The Rashba SOI is negligible in a symmetric QW, and the impurity-induced SOI effect turns out to be small. Expecting the physical picture to remain intact with the negligence of the Dresselhaus SOI, we leave the inclusion of it to future investigation. Driven by an electri...

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Spin-dependent transport of electrons in the presence of a smooth lateral potential and spin-orbit interaction

Cited by 21 publications

References 18 publications

Spin relaxation in narrow wires of a two-dimensional electron gas

Spin relaxation in narrow wires of a two-dimensional electron gas

Measurement of noncommuting spin components using spin-orbit interaction

Resonant spin dipole induced by an in-plane potential gradient spin-orbit interaction

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