Quantum splitter controlled by Rasha spin-orbit coupling

Shelykh, I. A.; Галкин, Н. Г.; Bagraev, N. T.

doi:10.1103/physrevb.72.235316

Cited by 70 publications

(56 citation statements)

References 46 publications

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“…This is different from the results given in Ref. 15, where P z 1,2 = 0. We attribute this to the fact that the adiabatic approximation was adopted in Ref.…”

Section: Resultscontrasting

confidence: 55%

“…We attribute this to the fact that the adiabatic approximation was adopted in Ref. 15 in which case, the spin of the carrier in the ring is either parallel or antiparallel to the Rashba field ⃗ B R . The present model, however, uses the nonadiabatic approximation, for which the up and down spin eigenstates do not generally align with the Rashba field.…”

Section: Resultsmentioning

confidence: 99%

“…14 The effects of RSOC and magnetic flux on charge and spin currents in a asymmetrically coupled 3-lead ring have been investigated by Shelykh et al, and they have shown a Electronic mail: zhailixue@126.com that such a system can act as both a quantum splitter and spin filter. 15 Various other aspects of spin dependent transport in multi-terminal mesoscopic rings have also been investigated, including charge and spin currents, 16 the number of terminals, 17 the effects of coupling between the leads and the ring, 18 and zero-conductance resonances. 19 Although there have been a few reports involving spin dependent transport in multi-terminal mesoscopic rings, [14][15][16][17][18][19][20] there have been, to the best of our knowledge, few works 20 related to the components of the spin polarization vectors in 3-lead rings.…”

Section: Introductionmentioning

confidence: 99%

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Spin conductances and spin polarization components in a three-terminal ring subject to Rashba coupling

2015

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Spin dependent transport in one-dimensional (1D) three-terminal rings is investigated in the presence of the Rashba spin-orbit coupling (RSOC). We focus on the spin dependent conductances and the components of the spin polarization vectors of the currents in the outgoing terminals. For this purpose, the transmission coefficients with respect to the σx, σy and σz basis are obtained, and the three components of the spin polarization vectors are evaluated analytically. The total conductances, the spin dependent conductances and the polarization components are obtained as functions of the incident electron energy, as well as the RSOC strength, for the totally symmetric, partially symmetric and asymmetric cases. It is found that the spin polarizations corresponding to the σy basis are zero, and that there is a symmetry in the total conductances, the spin dependent conductances and the polarization components for symmetric cases, i.e., G1 = G2, g1τ=g2−τ, and P1i=−P2i(i=x,z). This symmetry is attributed to the rotational symmetry in the symmetrically coupled rings. For asymmetric cases, however, it is broken by the asymmetric lead-ring configuration.

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“…This is different from the results given in Ref. 15, where P z 1,2 = 0. We attribute this to the fact that the adiabatic approximation was adopted in Ref.…”

Section: Resultscontrasting

confidence: 55%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Spin conductances and spin polarization components in a three-terminal ring subject to Rashba coupling

2015

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“…It was then proposed to use mesoscopic gated AharonovBohm (AB) rings as a possible basis of various spintronic devices such as spin transistors [2,3], spin filters [4,5,6], and quantum splitters [6]. The conductance of such structures depends both on the magnetic and the electric fields applied perpendicular to the interface of the structure.…”

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confidence: 99%

Proposal for a Mesoscopic Optical Berry-Phase Interferometer

et al. 2009

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We propose a novel spin-optronic device based on the interference of polaritonic waves traveling in opposite directions and gaining topological Berry phase. It is governed by the ratio of the TE-TM and Zeeman splittings, which can be used to control the output intensity. Due to the peculiar orientation of the TE-TM effective magnetic field for polaritons, there is no analogue of the Aharonov-Casher phaseshift existing for electrons.PACS numbers: 71.36.+c,71.35.Lk,03.75.Mn The problem of the spin dynamics is one of the most interesting in mesoscopic physics. The investigations in this field are stimulated by the possibility of creation of nanodevices, where the spins of the single particles could be precisely manipulated and controlled. The first device of this type, namely spin transistor, was proposed in early 90's in the pioneer work of Datta and Das [1], who used an analogy between the precession of the electron spin provided by Rashba spin-orbit interaction (SOI) and the rotation of the polarization plane of light in optically anisotropic media.However, the experimental realization of the spin transistor proposed by Datta and Das turned out to be quite complicated, due to the extremely low efficiency of spin injection from ferromagnetic to semiconductor materials. It was then proposed to use mesoscopic gated AharonovBohm (AB) rings as a possible basis of various spintronic devices such as spin transistors [2,3], spin filters [4,5,6], and quantum splitters [6]. The conductance of such structures depends both on the magnetic and the electric fields applied perpendicular to the interface of the structure. The magnetic field provides the AB phaseshift between the waves propagating in the clockwise and anticlockwise directions thus resulting in the oscillations of the conductance.The electric field applied perpendicular to the plane of the ring also affects the conductance. It has a two-fold effect. First, it changes the carrier wavenumber thus leading to conductance oscillations analogical to those observed in the Fabry-Perot resonator. Second, it induces the Rashba SOI and creates the dynamical phaseshift between the waves propagating within the ring. It consists of Aharonov -Casher (AC) phaseshift, arising from different values of the wavenumbers for the waves propagating in opposite directions [3,7], and a Berry (geometric) phase term [2], accumulated during the adiabatic evolution of the electron's spin in the inhomogeneous effective magnetic field created by Rashba SOI and external magnetic field perpendicular to the structure's interface. As a result, the conductance of the mesoscopic ring exhibits oscillations [8] as a function of the perpendicular electric field.It was recently proposed that in the domain of mesoscopic optics the controllable manipulation of the spin of excitons and exciton-polaritons can provide a basis for the construction of optoelectronic devices of the new generation, called spin-optronic devices [9]. The first element of this type, polarization-controlled optical gate, was recen...

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“…10,11,12,13,14 In this Letter, we introduce Rashba interaction to act locally on one component quantum dot(QD) of a triple-QD ring with three terminals. Our theoretical investigation indicates that it is possible to form the pure spin current in one of the three leads even in the absence of a magnetic field.…”

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confidence: 99%

Tunable pure spin currents in a triple-quantum-dot ring

Gong

Zheng

Lü

2008

Applied Physics Letters

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Electron transport properties in a triple-quantum-dot ring with three terminals are theoretically studied. By introducing local Rashba spin-orbit interaction on an individual quantum dot, we calculate the charge and spin currents in one lead. We find that a pure spin current appears in the absence of a magnetic field. The polarization direction of the spin current can be inverted by altering the bias voltage. In addition, by tuning the magnetic field strength, the charge and spin currents reach their respective peaks alternately.PACS numbers: 73.63. Kv, 71.70.Ej, One of the central issue in spintronics is how to realize the spin accumulation and spin transport in nanodevices. Recently, there has been many theoretical proposals to achieve the pure spin current without an accompanying charge current in mesoscopic systems, such as the use of spin Hall effects, 1,2 optical spin orientation by linearly polarized light, 3,4 adiabatic or nonadiabatic spin pumping in metals and semiconductors,generation in three-terminal spin devices. 7 Among these schemes, spin-orbit(SO) coupling is exploited to influences the electron spin state. In particular, in low-dimensional structures Rashba SO interaction comes into play by introducing an electric potential to destroy the symmetry of space inversion in an arbitrary spatial direction.8,9 Thus, by virtue of the Rashba interaction, electric control and manipulation of the electronic spin state is feasible. 10,11,12,13,14 In this Letter, we introduce Rashba interaction to act locally on one component quantum dot(QD) of a triple-QD ring with three terminals. Our theoretical investigation indicates that it is possible to form the pure spin current in one of the three leads even in the absence of a magnetic field. And the polarization direction of the spin current can be inverted by altering the bias voltage.The structure that we consider is illustrated in Fig.1. The single-particle Hamiltonian for an electron in such a structure can be written as H s = H 0 + H so = P 2 2m * + V (r) + H so where, accompanying the kinetic energy term P 2 2m * , the electron confined potential V (r) defines the structure geometry; And H so = y 2 · [α(σ × p) + (σ × p)α] denotes the local Rashba SO coupling on QD-2 (QD-j represents the QD with a single-particle level ε j shown in Fig.1(a)). We select the basis set {ψ kj χ σ , ψ j χ σ }(j=1,2,3) to second-quantize the Hamiltonian. The wavefunctions ψ j and ψ kj have the physical meaning of the orbital eigenstates of the isolated QD and leads, in the absence of Rashba interaction, where k j indicates the continuum state in lead-j. χ σ with σ =↑, ↓ denotes the eigenstates of Pauli spin operatorσ z .The second-quantized Hamiltonian consists of three parts:where c † kj σ and d † jσ (c kj σ and d jσ ) are the creation (annihilation) operators corresponding to the basis states in lead-j and QD-j. ε kj is the single-particle level in lead-j. V jσ = ψ j χ σ |H s |ψ kj χ σ denotes QDlead hopping amplitude. The interdot hopping amplitude, written as t lσ = t l − iσs...

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Quantum splitter controlled by Rasha spin-orbit coupling

Cited by 70 publications

References 46 publications

Spin conductances and spin polarization components in a three-terminal ring subject to Rashba coupling

Spin conductances and spin polarization components in a three-terminal ring subject to Rashba coupling

Proposal for a Mesoscopic Optical Berry-Phase Interferometer

Tunable pure spin currents in a triple-quantum-dot ring

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